Showing 1–50 of 420 results for author: Joshi, R

Super-Constant Weight Dicke States in Constant Depth Without Fanout

Authors: Lucas Gretta, Meghal Gupta, Malvika Raj Joshi

Abstract: An $n$-qubit Dicke state of weight $k$, is the uniform superposition over all $n$-bit strings of Hamming weight $k$. Dicke states are an entanglement resource with important practical applications in the NISQ era and, for instance, play a central role in Decoded Quantum Interferometry (DQI). Furthermore, any symmetric state can be expressed as a superposition of Dicke states. First, we give expl… ▽ More An $n$-qubit Dicke state of weight $k$, is the uniform superposition over all $n$-bit strings of Hamming weight $k$. Dicke states are an entanglement resource with important practical applications in the NISQ era and, for instance, play a central role in Decoded Quantum Interferometry (DQI). Furthermore, any symmetric state can be expressed as a superposition of Dicke states. First, we give explicit constant-depth circuits that prepare $n$-qubit Dicke states for all $k \leq \text{polylog}(n)$, using only multi-qubit Toffoli gates and single-qubit unitaries. This gives the first $\text{QAC}^0$ construction of super-constant weight Dicke states. Previous constant-depth constructions for any super-constant $k$ required the FANOUT$_n$ gate, while $\text{QAC}^0$ is only known to implement FANOUT$_k$ for $k$ up to $\text{polylog}(n)$. Moreover, we show that any weight-$k$ Dicke state can be constructed with access to FANOUT$_{\min(k,n-k)}$, rather than FANOUT$_n$. Combined with recent hardness results, this yields a tight characterization: for $k \leq n/2$, weight-$k$ Dicke states can be prepared in $\text{QAC}^0$ if and only if FANOUT$_k \in \text{QAC}^0$. We further extend our techniques to show that, in fact, \emph{any} superposition of $n$-qubit Dicke states of weight at most $k$ can be prepared in $\text{QAC}^0$ with access to FANOUT$_k$. Taking $k = n$, we obtain the first $O(1)$-depth unitary construction for arbitrary symmetric states. In particular, any symmetric state can be prepared in constant depth on quantum hardware architectures that support FANOUT$_n$, such as trapped ions with native global entangling operations. △ Less

Submitted 16 April, 2026; originally announced April 2026.

Real-time polarization tuning in Mach-Zehnder interferometer using electro-optically modulated twist angles of nematic liquid crystal Note: This paper has been accepted for publication in "Journal of Theoretical and Applied Physics"

Authors: Rajneesh Joshi, Gyaprasad

Abstract: We propose a theoretical framework to dynamically control the degree of polarization of light by using the superposition of incoherent orthogonally polarized beams in a Mach-Zehnder interferometer incorporating a twisted nematic liquid crystal cell in one of its arms. The liquid crystal acts as an elecro-optically controlled polarization rotator, where the applied electric field changes the twist… ▽ More We propose a theoretical framework to dynamically control the degree of polarization of light by using the superposition of incoherent orthogonally polarized beams in a Mach-Zehnder interferometer incorporating a twisted nematic liquid crystal cell in one of its arms. The liquid crystal acts as an elecro-optically controlled polarization rotator, where the applied electric field changes the twist of molecules inside the nematic liquid crystal, thereby altering the plane of polarization. This controllable voltage dependent polarization rotation causes manipulation of the output degree of polarization. The resulting system allows real-time, tunable control over the degree of polarization, offering advantages over traditional static or reflection-based approaches, which often suffer from intensity losses or manual errors. We also observe that in the interference of fully coherent orthogonally polarized beams through a similar configuration, the degree of polarization is always equal to 1, whereas the orientation of linear state of polarization is changed with voltage. △ Less

Submitted 12 April, 2026; originally announced April 2026.

Comments: 8 pages, 6 Figures,

Electro-optically controlled photon group velocity, temporal walk-off and two-photon entanglement via nematic liquid crystal

Authors: Gyaprasad, Rajneesh Joshi

Abstract: The propagation of the quantum states of light in dispersive and anisotropic media is a fundamental problem in quantum optics. We present a unified theoretical framework for the propagation of the quantum states of light in voltage-controlled nematic liquid crystals, incorporating both material dispersion and electrically tunable birefringence. By treating photons as finite-bandwidth wave packets,… ▽ More The propagation of the quantum states of light in dispersive and anisotropic media is a fundamental problem in quantum optics. We present a unified theoretical framework for the propagation of the quantum states of light in voltage-controlled nematic liquid crystals, incorporating both material dispersion and electrically tunable birefringence. By treating photons as finite-bandwidth wave packets, we derive analytical expressions for group velocoity, temporal walk-off, and phase evolution of orthogonally polarized modes. The results demonstrate that nematic liquid crystals can serve as electrically tunable quantum photonic devices capable of manipulating photon arrival times, polarization correlations, and temporal indistinguishability of entangled photon pairs. These results show the direct relevance to quantum communication and photonic quantum information processing. △ Less

Submitted 12 April, 2026; originally announced April 2026.

Comments: 9 pages, 3 Figures

Observation of genuine $2+1$D string dynamics in a U$(1)$ lattice gauge theory with a tunable plaquette term on a trapped-ion quantum computer

Authors: Rohan Joshi, Yizhuo Tian, Kevin Hemery, N. S. Srivatsa, Jesse J. Osborne, Henrik Dreyer, Enrico Rinaldi, Jad C. Halimeh

Abstract: Quantum simulations of high-energy physics in $2+1$D can probe dynamical phenomena nonexistent in one spatial dimension and access regimes that are challenging for existing classical simulation methods. For string dynamics -- relevant to hadronization -- a plaquette term is required to realize genuine $2+1$D behavior, as it endows the gauge field with dynamics and enables the propagation of photon… ▽ More Quantum simulations of high-energy physics in $2+1$D can probe dynamical phenomena nonexistent in one spatial dimension and access regimes that are challenging for existing classical simulation methods. For string dynamics -- relevant to hadronization -- a plaquette term is required to realize genuine $2+1$D behavior, as it endows the gauge field with dynamics and enables the propagation of photon-like excitations. Here, we realize a U$(1)$ quantum link model of quantum electrodynamics in two spatial dimensions with a tunable plaquette term on a \texttt{Quantinuum System Model H2} quantum computer. We implement, to our knowledge, the largest quantum simulation of string-breaking dynamics reported to date, on a $5 \times 4$ matter-site square lattice using $51$ qubits. The simulation uses a shallow circuit design with a two-qubit gate depth of $28$ per Trotter step and up to $1540$ entangling gates. Starting from far-from-equilibrium string configurations, we measure the probability for the string to propagate within the lattice plane and find signatures of genuine $2+1$D dynamics only when the plaquette term is present. In a resonant regime, we observe the annihilation of string segments accompanied by the production of electron--positron pairs that screen them. We further find that, only with a nonzero plaquette term, matter creation extends across the lattice plane rather than remaining confined to the initial string path. These results experimentally realize string breaking and demonstrate the emergence of dynamical gauge fields in two spatial dimensions, establishing a route to photon-like propagation in programmable quantum simulators of gauge theories. △ Less

Submitted 8 April, 2026; originally announced April 2026.

Comments: $12+13$ pages, $4+12$ figures, $0+1$ table. See parallel submission by K. Xu et al., "Observation of glueball excitations and string breaking in a $2+1$D $\mathbb{Z}_2$ lattice gauge theory on a trapped-ion quantum computer''

Observation of glueball excitations and string breaking in a $2+1$D $\mathbb{Z}_2$ lattice gauge theory on a trapped-ion quantum computer

Authors: Kaidi Xu, Umberto Borla, Kevin Hemery, Rohan Joshi, Henrik Dreyer, Enrico Rinaldi, Jad C. Halimeh

Abstract: A major goal of the quantum simulation of high-energy physics (HEP) is to probe real-time nonperturbative far-from-equilibrium quantum processes underlying phenomena such as hadronization in quantum chromodynamics (QCD). The quantum simulation of the dynamics of confining strings and glueballs, both essential aspects of quark confinement, in a controllable first-principles way is an important step… ▽ More A major goal of the quantum simulation of high-energy physics (HEP) is to probe real-time nonperturbative far-from-equilibrium quantum processes underlying phenomena such as hadronization in quantum chromodynamics (QCD). The quantum simulation of the dynamics of confining strings and glueballs, both essential aspects of quark confinement, in a controllable first-principles way is an important step towards this goal. Here, we realize a $\mathbb{Z}_2$ lattice gauge theory in $2+1$D with a tunable plaquette term on a \texttt{Quantinuum System Model H2} trapped-ion quantum computer. We implement a shallow depth-6 Trotter circuit on a $6 \times 5$ matter-site square lattice utilizing all $56$ available qubits to execute over $1000$ entangling gates. We prepare far-from-equilibrium initial string configurations that we quench across a range of parameters to observe rich dynamical phenomena, such as the formation of gauge-invariant closed-loop excitations reminiscent of glueballs in QCD and multi-order string breaking accompanied by spontaneous matter creation. We further demonstrate experimentally that the system displays genuine $2+1$D dynamics, as evidenced by string snapshots over time that cannot be trivially mapped to $1+1$D physics. Our results demonstrate digital quantum simulations of nonequilibrium dynamics in a higher-dimensional lattice gauge theory and provide an experimentally accessible setting for phenomena related to confinement physics. △ Less

Submitted 8 April, 2026; originally announced April 2026.

Comments: $12+7$ pages, $4+6$ figures, $0+1$ table. See parallel submission by R. Joshi et al., "Observation of genuine $2+1$D string dynamics in a U$(1)$ lattice gauge theory with a tunable plaquette term on a trapped-ion quantum computer''

Galactic-scale evolution of classical and complex radio galaxies. Impact of ambient morphology and jet geometry

Authors: Gourab Giri, Prajnadipt Ghosh, Ravi Joshi, Anderson Caproni, Paola Rossi, Gianluigi Bodo, Sayan Kundu, Kshitij Thorat, Swarna Chatterjee, Dario Borgogno, Valerio Vittorini, Marco Tavani

Abstract: Extragalactic jets exhibit a wide range of propagation orientations relative to the host galaxy's principal axis. This study investigate the spatiotemporal evolution of jets as a function of their propagation direction within their triaxial hosts-introducing varying degrees of environmental hindrance-and as a function of internal jet properties (while maintaining identical jet power)-introducing v… ▽ More Extragalactic jets exhibit a wide range of propagation orientations relative to the host galaxy's principal axis. This study investigate the spatiotemporal evolution of jets as a function of their propagation direction within their triaxial hosts-introducing varying degrees of environmental hindrance-and as a function of internal jet properties (while maintaining identical jet power)-introducing varying collimation and thrust. Observational data on extended radio sources are re-analyzed to identify key traits arising from variations in jet orientation and intrinsic properties. These findings are then systematically tested using a suite of 3D RMHD simulations. When a jet propagates along host's major axis (path of maximal environmental resistance), it produces an X-shaped morphology with secondary lobe aligns along the minor axis, co-evolving actively alongside the active jet. At intermediate angles to the major axis, the jet morphology transitions into a double-boomerang structure with notably curved lobes. Such lobes are interestingly regenerative through both backflow and jet precession mechanisms, making it difficult to disentangle their origin. Jets propagating along the minor axis (path of minimal resistance) exhibit faster propagation, forming classical double-lobed sources. With increased thrust and improved collimation (keeping jet power constant), these jets advance even more rapidly, potentially evolving into giant radio galaxy candidates. Counterexample sources that deviate from these traits were also modeled. The spatial variation of internal turbulence shows significant fluctuations below 1 kpc, with stronger magnetic fields further suppressing these irregularities. Magnetic field plays a key role in the radiative appearance of these sources, modulating features like missing or one-sided (wing) lobe emission, filamentary structures, and warmspot versus hotspot formation. △ Less

Submitted 7 April, 2026; originally announced April 2026.

Comments: Article accepted for publication in A&A journal. (19 Figs, 4 Tables)

Parity $\notin$ QAC0 $\iff$ QAC0 is Fourier-Concentrated

Authors: Lucas Gretta, Meghal Gupta, Malvika Raj Joshi

Abstract: A major open problem in understanding shallow quantum circuits (QAC$^0$) is whether they can compute Parity. We show that this question is solely about the Fourier spectrum of QAC$^0$: any QAC$^0$ circuit with non-negligible high-level Fourier mass suffices to exactly compute PARITY in QAC$^0$. Thus, proving a quantum analog of the seminal LMN theorem for AC$^0$ is necessary to bound the quantum c… ▽ More A major open problem in understanding shallow quantum circuits (QAC$^0$) is whether they can compute Parity. We show that this question is solely about the Fourier spectrum of QAC$^0$: any QAC$^0$ circuit with non-negligible high-level Fourier mass suffices to exactly compute PARITY in QAC$^0$. Thus, proving a quantum analog of the seminal LMN theorem for AC$^0$ is necessary to bound the quantum circuit complexity of PARITY. In the other direction, LMN does not fully capture the limitations of AC$^0$. For example, despite MAJORITY having $99\%$ of its weight on low-degree Fourier coefficients, no AC$^0$ circuit can non-trivially correlate with it. In contrast, we provide a QAC$^0$ circuit that achieves $(1-o(1))$ correlation with MAJORITY, establishing the first average-case decision separation between AC$^0$ and QAC$^0$. This suggests a uniquely quantum phenomenon: unlike in the classical setting, Fourier concentration may largely characterize the power of QAC$^0$. PARITY is also known to be equivalent in QAC$^0$ to inherently quantum tasks such as preparing GHZ states to high fidelity. We extend this equivalence to a broad class of state-synthesis tasks. We demonstrate that existing metrics such as trace distance, fidelity, and mutual information are insufficient to capture these states and introduce a new measure, felinity. We prove that preparing any state with non-negligible felinity, or derived states such as poly(n)-weight Dicke states, implies PARITY $\in$ QAC$^0$. △ Less

Submitted 3 April, 2026; originally announced April 2026.

Tunable Floquet selection rules in a driven Ising chain

Authors: Rishi Paresh Joshi, Sanchayan Banerjee, Sneha Narasimha Moorthy, Tapan Mishra

Abstract: We study a periodically driven spin-$1/2$ Ising chain with a nearest-neighbour coupling and longitudinal field while a weak transverse field induces single-spin flips. Through Floquet perturbation theory (FPT), we obtain signatures of Hilbert space fragmentation (HSF) and an unconventional form of dynamical localisation which we call the Floquet freezing. Our analysis suggests that these observati… ▽ More We study a periodically driven spin-$1/2$ Ising chain with a nearest-neighbour coupling and longitudinal field while a weak transverse field induces single-spin flips. Through Floquet perturbation theory (FPT), we obtain signatures of Hilbert space fragmentation (HSF) and an unconventional form of dynamical localisation which we call the Floquet freezing. Our analysis suggests that these observations emerge due to a single Floquet selection rule that dictates the prethermal dynamics. For a special value of the field-to-interaction strength ratio together with commensurate drive periods, this rule permits only a constrained subset of bulk spin flips, leading to prethermal HSF in the full spin-$1/2$ Hilbert space. Under open boundary conditions, the same rule suppresses boundary spin flips up to higher order in perturbation and produces long-lived prethermal edge memory, which is neither topological in origin nor is a strong zero mode. Furthermore, under periodic boundary conditions, the largest surviving fragment is exactly the PXP sector at leading order and therefore exhibits Floquet-inherited scar phenomenology in the prethermal window. At higher commensurate ratios of field strength to interaction strength, all first-order single-spin-flip channels are suppressed and the system enters a regime of Floquet freezing. Hence, our study leverages the selection rules obtained through Floquet perturbation theory to obtain exotic prethermal phenomena at different parameter regimes. △ Less

Submitted 24 March, 2026; originally announced March 2026.

Comments: 18 pages, 10 figures

Magnetic flux distribution, quasiparticle spectroscopy, and quality factors in Nb films for superconducting qubits

Authors: Amlan Datta, Bicky S. Moirangthem, Kamal R. Joshi, Anthony P. Mcfadden, Florent Lecocq, Raymond W. Simmonds, Makariy A. Tanatar, Matthew J. Kramer, Ruslan Prozorov

Abstract: Niobium is a practical material platform for superconducting microwave circuits; however, device-level performance can vary significantly depending on film growth and processing conditions. We compare three epitaxial Nb films grown on $c-$plane sapphire substrates under nominally identical conditions, except for the deposition temperature. To correlate internal quality factors, $Q_{\mathrm {i}}$,… ▽ More Niobium is a practical material platform for superconducting microwave circuits; however, device-level performance can vary significantly depending on film growth and processing conditions. We compare three epitaxial Nb films grown on $c-$plane sapphire substrates under nominally identical conditions, except for the deposition temperature. To correlate internal quality factors, $Q_{\mathrm {i}}$, with material properties, we combine magneto-optical imaging of magnetic flux distribution with quasiparticle spectroscopy via measurements of the London penetration depth, $λ(T)$. In the low-$Q_{\mathrm i}$ film, there is a lesser ability to screen the magnetic field and an irregular temperature variation of $λ(T)$, implying the existence of localized in-gap states. High $Q_{\mathrm i}$ films show the opposite trend. We conclude that our measurements provide an efficient method for characterizing and optimizing superconducting films for quantum informatics applications. △ Less

Submitted 24 March, 2026; originally announced March 2026.

Formation and rising phase of a flux rope through data-constrained simulations

Authors: M. V. Sieyra, A. Strugarek, A. Prasad, A. Wagner, P. Démoulin, F. Moreno-Insertis, A. J. Finley, R. Joshi, A. Blaise, A. S. Brun, E. Buchlin

Abstract: Context. Data-constrained models incorporate observed photospheric magnetic fields. However, due to the lack of magnetic field information in the rest of the solar atmosphere, models rely on extrapolations that, in most cases, neglect the Lorentz force. Nevertheless, this force is present in the lower atmosphere and may play a key role in destabilising the equilibrium configuration and triggering… ▽ More Context. Data-constrained models incorporate observed photospheric magnetic fields. However, due to the lack of magnetic field information in the rest of the solar atmosphere, models rely on extrapolations that, in most cases, neglect the Lorentz force. Nevertheless, this force is present in the lower atmosphere and may play a key role in destabilising the equilibrium configuration and triggering eruptions. Aims. This study seeks to understand and reproduce a solar eruption SOL2014-12-18T21:41 that occurred in active region NOAA 12241, preceded by an M6.9 flare, and to investigate the impact of relaxing the initial force-free assumption. Methods. The resistive and compressible magnetohydrodynamic simulation is initiated using a non-force-free magnetic field extrapolated from a photospheric vector magnetogram taken minutes before the flare. The simulation includes a stratified atmosphere and non-ideal effects such as thermal conduction and radiative cooling. Results. A flux rope forms and rises in the simulation, carrying away dense material from the lower solar atmosphere. Its formation results from the non-zero Lorentz force acting on the initial sheared arcade, without assuming pre-existing flux ropes or photospheric driving motions. The flux rope is then deflected toward regions of low magnetic pressure, escaping the domain at 350 km/s with approximately constant acceleration. Conclusions. A robust numerical framework for modelling flaring active regions was applied to the eruption of NOAA AR12241 as a case study, assuming a realistic non-force-free magnetic field near the flare onset. It exemplifies how an initial Lorentz force imbalance can successfully trigger a flux rope formation that later escapes the simulation domain. It also enables comparison with real observations through the addition of a stratified atmosphere spanning from the photosphere to the corona. △ Less

Submitted 14 March, 2026; originally announced March 2026.

Comments: 17 pages, 14 figures

Measuring the evolution of stellar bars with the host galaxy's spin

Authors: Robin Joshi, Scott M. Croom, Stefania Barsanti, Elizabeth J. Iles, Joss Bland-Hawthorn, Jesse van de Sande

Abstract: We examine to what extent the galaxy spin parameter proxy ($λ_R$) is affected by bar formation and how it is related to the strong and weak classifications of stellar bars. By creating mock observations of a simulated galaxy, we show that the emergence of a stellar bar can cause mass-weighted $λ_R$ to decrease by up to 16%, depending on the bar's orientation. This decrease can be exaggerated if th… ▽ More We examine to what extent the galaxy spin parameter proxy ($λ_R$) is affected by bar formation and how it is related to the strong and weak classifications of stellar bars. By creating mock observations of a simulated galaxy, we show that the emergence of a stellar bar can cause mass-weighted $λ_R$ to decrease by up to 16%, depending on the bar's orientation. This decrease can be exaggerated if there is a burst of star formation due to the bar driving gas to the center of the galaxy. We use the SAMI galaxy survey to show that weakly barred galaxies have statistically significant younger average stellar populations, higher galaxy spin proxy and higher specific star formation rates compared to strongly barred galaxies within one effective radius. If we consider galaxies with average light-weighted stellar population age less than 3 Gyr within one effective radius, we still find weakly barred galaxies to have a higher galaxy spin proxy than strongly barred galaxies. Based on these trends found from the SAMI galaxy survey, we suggest weakly barred galaxies are rapidly forming, similar to the bar formation process seen in simulations, while strongly barred galaxies are undergoing slower (secular) evolution. △ Less

Submitted 9 March, 2026; originally announced March 2026.

Comments: 15 pages, 15 figures. Accepted for publication in MNRAS

Quasiparticle spectroscopy in tantalum films with different Ta/sapphire interfaces

Authors: Bicky S. Moirangthem, Kamal R. Joshi, Anthony P. Mcfadden, Jin-Su Oh, Amlan Datta, Makariy A. Tanatar, Florent Lecocq, Raymond W. Simmonds, Lin Zhou, Matthew J. Kramer, Ruslan Prozorov

Abstract: One of the crucial aspects of current research in quantum information science is the identification and control of loss mechanisms in superconducting circuits. Although microwave measurements directly quantify device performance, additional techniques that probe quasiparticle excitations in superconducting films are needed to understand the microscopic mechanisms underlying dissipation and decoher… ▽ More One of the crucial aspects of current research in quantum information science is the identification and control of loss mechanisms in superconducting circuits. Although microwave measurements directly quantify device performance, additional techniques that probe quasiparticle excitations in superconducting films are needed to understand the microscopic mechanisms underlying dissipation and decoherence. Here, we present results from quasiparticle spectroscopy of Ta/sapphire films by measuring the Meissner-state magnetic susceptibility using a precision frequency-domain resonator specifically designed for thin films. We find direct evidence for additional low-energy excitations in samples with lower internal quality factors. These excitations are consistent with deep subgap states due to two-level systems, Yu-Shiba-Rusinov states near the gap edge, and perhaps other pair-breaking mechanisms. The developed non-destructive frequency-domain quasiparticle spectroscopy is a valuable addition to the quantum materials toolbox. △ Less

Submitted 6 March, 2026; originally announced March 2026.

Construction of Cyclic Codes over a Class of Matrix Rings

Authors: Soham Ravikant Joshi, Shikha Patel, Om Prakash

Abstract: Let $ \mathbb F_2[u]/ \langle u^k \rangle= \mathbb F_2+u\mathbb F_2+u^2\mathbb F_2+\cdots+u^{k-1}\mathbb F_2 ,$ where $u^k=0$ for a positive integer $k$, and $\mathcal{R}=M_4 (\mathbb F_2( u)/ \langle u^k \rangle)$ be the finite noncommutative non-chain matrix ring of order $4\times4$. This paper presents the construction of cyclic codes over the finite field $\mathbb F_{16}$ via the considered ma… ▽ More Let $ \mathbb F_2[u]/ \langle u^k \rangle= \mathbb F_2+u\mathbb F_2+u^2\mathbb F_2+\cdots+u^{k-1}\mathbb F_2 ,$ where $u^k=0$ for a positive integer $k$, and $\mathcal{R}=M_4 (\mathbb F_2( u)/ \langle u^k \rangle)$ be the finite noncommutative non-chain matrix ring of order $4\times4$. This paper presents the construction of cyclic codes over the finite field $\mathbb F_{16}$ via the considered matrix ring $\mathcal{R}$. In this connection, first, we discuss the structure of the ring $\mathcal{R}$ and show that $\mathcal{R}$ is isomorphic to the ring $( \mathbb F_{16}+ v\mathbb F_{16} + v^2\mathbb F_{16} + v^3\mathbb F_{16}) + u(\mathbb F_{16} + v\mathbb F_{16} + v^2\mathbb F_{16} + v^3\mathbb F_{16}) + u^2(\mathbb F_{16} + v\mathbb F_{16} + v^2\mathbb F_{16}+ v^3\mathbb F_{16}) + \cdots + u^{k-1}(\mathbb F_{16} + v\mathbb F_{16} + v^2\mathbb F_{16} + v^3\mathbb F_{16})$ where $v^4=0, u^k=0, u^iv^j=v^ju^i$ for $i \in \{1,\dots, k-1\}$ and $j \in \{1, 2, 3\}$. Then, we establish the form of ideals of the ring $\mathcal{R}$ and related cyclic codes over $\mathcal{R}$. Further, we show that these cyclic codes can be written as the direct sums of $\mathcal{R}$-submodules of $\frac{\mathcal{R}[x]}{<x^n-1>}$, and derive the formula for the cardinality of cyclic codes over $\mathcal{R}$. Then, we consider the Euclidean and Hermitian duals of the derived cyclic codes over $\mathcal{R}$. Under the module isometry for $\mathcal{R}$, we use the Bachoc map and the Gray map, which takes a derived cyclic code over $\mathcal{R}$ to $\mathbb F_{16}$. Finally, we provide some non-trivial examples of linear codes over $\mathbb F_{16}$ with good parameters that support our derived results and compare a few codes with existing codes in the literature. △ Less

Submitted 20 February, 2026; originally announced February 2026.

Comments: 30

MSC Class: 12E20; 94B05; 94B15

Magneto-optical study of Nb thin films for superconducting qubits

Authors: Amlan Datta, Kamal R. Joshi, Sunil Ghimire, Makariy A. Tanatar, Cameron J. Kopas, Jayss Marshall, Josh Y. Mutus, David P. Pappas, Matthew J. Kramer, Ruslan Prozorov

Abstract: Among the recognized sources of decoherence in superconducting qubits, the spatial inhomogeneity of the superconducting state and the possible presence of magnetic-flux vortices remain comparatively underexplored. Niobium is commonly used as a structural material in transmon qubits that host Josephson junctions, and excess dissipation anywhere in the transmon can become a bottleneck that limits ov… ▽ More Among the recognized sources of decoherence in superconducting qubits, the spatial inhomogeneity of the superconducting state and the possible presence of magnetic-flux vortices remain comparatively underexplored. Niobium is commonly used as a structural material in transmon qubits that host Josephson junctions, and excess dissipation anywhere in the transmon can become a bottleneck that limits overall quantum performance. The metal/substrate interfacial layer may simultaneously host pair-breaking loss channels (e.g., two-level systems, TLS) and control thermal transport, thereby affecting dissipation and temperature stability. Here, we use quantitative magneto-optical imaging of the magnetic-flux distribution to characterize the homogeneity of the superconducting state and the critical current density, $j_{c}$, in niobium films fabricated under different sputtering conditions. The imaging reveals distinct flux-penetration regimes, ranging from a nearly ideal Bean critical state to strongly nonuniform thermo-magnetic dendritic avalanches. By fitting the measured magnetic-induction profiles, we extract $j_{c}$ and correlate it with film physical properties and with measured qubit internal quality factors. Our results indicate that the Nb/Si interlayer can be a significant contributor to decoherence and should be considered an important factor that must be optimized. △ Less

Submitted 10 February, 2026; originally announced February 2026.

Effect of metal encapsulation on bulk superconducting properties of niobium thin films used in qubits

Authors: Amlan Datta, Kamal R. Joshi, Sunil Ghimire, Bicky S. Moirangthem, Makariy A. Tanatar, Mustafa Bal, Zuhawn Sung, Sabrina Garattoni, Francesco Crisa, Akshay Murthy, David A. Garcia-Wetten, Dominic P. Goronzy, Mark C. Hersam, Michael J. Bedzyk, Shaojiang Zhu, David Olaya, Peter Hopkins, Matthew J. Kramer, Alexander Romanenko, Anna Grassellino, Ruslan Prozorov

Abstract: Niobium metal occupies nearly 100\% of the volume of a typical 2D transmon device. While the aluminum Josephson junction is of utmost importance, maintaining quantum coherence across the entire device means that pair-breaking in Nb leads, capacitive pads, and readout resonators can be a major source of decoherence. The established contributors are surface oxides and hydroxides, as well as absorbed… ▽ More Niobium metal occupies nearly 100\% of the volume of a typical 2D transmon device. While the aluminum Josephson junction is of utmost importance, maintaining quantum coherence across the entire device means that pair-breaking in Nb leads, capacitive pads, and readout resonators can be a major source of decoherence. The established contributors are surface oxides and hydroxides, as well as absorbed hydrogen and oxygen. Metal encapsulation of freshly grown surfaces with non-oxidizing metals, preferably without breaking the vacuum, is a successful strategy to mitigate these issues. While the positive effects of encapsulation are undeniable, it is important to understand its impact on the macroscopic behavior of niobium films. We present a comprehensive study of the bulk superconducting properties of Nb thin films encapsulated with gold and palladium/gold, and compare them to those of bare Nb films. Magneto-optical imaging, magnetization, resistivity, and London and Campbell penetration depth measurements reveal significant differences in encapsulated samples. Both sputtered, and epitaxial Au-capped films exhibit the highest residual resistivity ratio and superconducting transition temperature, as well as the lowest upper critical field, London penetration depth, and critical current. These results are in good agreement with the microscopic theory of anisotropic normal and superconducting states of Nb. We conclude that pair-breaking in the bulk of niobium films, driven by disorder throughout the film rather than just at the surface, is a significant source of quantum decoherence in transmons. We also conclude that gold capping not only passivates the surface but also affects the properties of the entire film, significantly reducing the scattering rate due to defects likely induced by surface diffusion if the film is not protected immediately after fabrication. △ Less

Submitted 7 February, 2026; originally announced February 2026.

FiMI: A Domain-Specific Language Model for Indian Finance Ecosystem

Authors: Aboli Kathar, Aman Kumar, Anusha Kamath, Araveeti Srujan, Ashish Sharma, Chandra Bhushan, Divya Sorate, Duddu Prasanth Kumar, Evan Acharya, Harsh Sharma, Hrithik Kadam, Kanishk Singla, Keyur Doshi, Kiran Praveen, Kolisetty Krishna SK, Krishanu Adhikary, Lokesh MPT, Mayurdeep Sonowal, Nadeem Shaikh, Navya Prakash, Nimit Kothari, Nitin Kukreja, Prashant Devadiga, Rakesh Paul, Ratanjeet Pratap Chauhan , et al. (15 additional authors not shown)

Abstract: We present FiMI (Finance Model for India), a domain-specialized financial language model developed by National Payments Corporation of India (NPCI) for Indian digital payment systems. We develop two model variants: FiMI Base and FiMI Instruct. FiMI adapts the Mistral Small 24B architecture through a multi-stage training pipeline, beginning with continuous pre-training on 68 Billion tokens of curat… ▽ More We present FiMI (Finance Model for India), a domain-specialized financial language model developed by National Payments Corporation of India (NPCI) for Indian digital payment systems. We develop two model variants: FiMI Base and FiMI Instruct. FiMI adapts the Mistral Small 24B architecture through a multi-stage training pipeline, beginning with continuous pre-training on 68 Billion tokens of curated financial, multilingual (English, Hindi, Hinglish), and synthetic data. This is followed by instruction fine-tuning and domain-specific supervised fine-tuning focused on multi-turn, tool-driven conversations that model real-world workflows, such as transaction disputes and mandate lifecycle management. Evaluations reveal that FiMI Base achieves a 20\% improvement over the Mistral Small 24B Base model on finance reasoning benchmark, while FiMI Instruct outperforms the Mistral Small 24B Instruct model by 87\% on domain-specific tool-calling. Moreover, FiMI achieves these significant domain gains while maintaining comparable performance to models of similar size on general benchmarks. △ Less

Submitted 13 February, 2026; v1 submitted 5 February, 2026; originally announced February 2026.

Characteristic Classes Of Representations Of Lie Groups

Authors: Rohit Joshi, Steven Spallone

Abstract: An irreducible representation of a reductive Lie algebra, when restricted to a Cartan subalgebra, decomposes into weights with multiplicity. The first part of this paper outlines a procedure to compute symmetric polynomials (e.g., power sums) of this multiset of weights, as functions of the highest weight. Next, let G be a connected reductive complex algebraic group with maximal torus T. We expres… ▽ More An irreducible representation of a reductive Lie algebra, when restricted to a Cartan subalgebra, decomposes into weights with multiplicity. The first part of this paper outlines a procedure to compute symmetric polynomials (e.g., power sums) of this multiset of weights, as functions of the highest weight. Next, let G be a connected reductive complex algebraic group with maximal torus T. We express the restrictions of the Chern classes of irreducible representations of G to T, as polynomial functions in the highest weight. We do the same for Stiefel-Whitney classes of orthogonal representations. △ Less

Submitted 2 February, 2026; originally announced February 2026.

MSC Class: 20G20; 55R40; 05E05

String Breaking and Glueball Dynamics in $2+1$D Quantum Link Electrodynamics

Authors: Jiahao Cao, Rohan Joshi, Yizhuo Tian, N. S. Srivatsa, Jad C. Halimeh

Abstract: At the heart of quark confinement and hadronization, the physics of flux strings has recently become a focal point in the field of quantum simulation of high-energy physics (HEP). Despite considerable progress, a detailed understanding of the behavior of flux strings in quantum simulation-relevant lattice formulations of gauge theories has remained limited to the lowest truncations of the gauge fi… ▽ More At the heart of quark confinement and hadronization, the physics of flux strings has recently become a focal point in the field of quantum simulation of high-energy physics (HEP). Despite considerable progress, a detailed understanding of the behavior of flux strings in quantum simulation-relevant lattice formulations of gauge theories has remained limited to the lowest truncations of the gauge field, which are severely limited in their ability to draw conclusions about the quantum field theory limit. Here, we employ tensor network simulations to investigate the behavior of flux strings in a quantum link formulation of $2+1$D quantum electrodynamics (QED) with a spin-$1$ representation of the gauge field. We first map out the ground-state phase diagram of this model in the presence of two spatially separated static charges, revealing distinct microscopic processes responsible for string breaking, including a two-stage breaking mechanism not possible in the spin-$\frac{1}{2}$ formulation. Starting in different initial product state string configurations, we then explore far-from-equilibrium quench dynamics across various parameter regimes, demonstrating genuine $2+1$D real-time string breaking and glueball-like bound state formation, with the latter not possible in the spin-$\frac{1}{2}$ formulation. In and out of equilibrium, we consider different values and placements of the static charges. Finally, we provide efficient qudit circuits for a quantum simulation experiment in which our results can be observed in state-of-the-art ion-trap setups. Our findings lay the groundwork for quantum simulations of flux strings towards the quantum field theory limit. △ Less

Submitted 22 January, 2026; originally announced January 2026.

Comments: $21$ pages, $11$ figures, $2$ tables

A Computational Phase Function Method for $α-α$ Scattering: Wavefunction Construction from Single and Two-Term Morse Potentials

Authors: Anil Khachi, Shikha Awasthi, Tarachand Verma, Ranjana Joshi

Abstract: In this work, the phase function method (PFM) is employed for the first time to explicitly construct scattering wavefunctions for the $αα$ system using a single-term Morse potential. Unlike earlier PFM-based studies that primarily focused on reproducing scattering phase shifts, the present approach directly reconstructs radial wavefunctions for the $\ell = 0$, 2, and 4 partial waves without solvin… ▽ More In this work, the phase function method (PFM) is employed for the first time to explicitly construct scattering wavefunctions for the $αα$ system using a single-term Morse potential. Unlike earlier PFM-based studies that primarily focused on reproducing scattering phase shifts, the present approach directly reconstructs radial wavefunctions for the $\ell = 0$, 2, and 4 partial waves without solving the Schr$\ddot{\text{o}}$dinger equation. For comparison, we adopt the interaction potential parameters reported by Sastri et al., who determined them using a two-term reference potential approach with genetic algorithm optimization to accurately reproduce the $αα$ scattering phase shifts. Without re-optimization, we construct the corresponding wavefunctions and find very good agreement with those obtained using our single-term Morse potential. The results also show excellent consistency with the resonating-group method calculations of Hiura \textit{et al.}.These findings demonstrate that PFM provides a numerically stable, efficient, and unified framework for scattering wavefunction construction in cluster-cluster systems. △ Less

Submitted 22 February, 2026; v1 submitted 16 January, 2026; originally announced January 2026.

Constant-Depth Unitary Preparation of Dicke States

Authors: Malvika Raj Joshi, Francisca Vasconcelos

Abstract: Dicke states serve as a critical resource in quantum metrology, communication, and computation. However, unitary preparation of Dicke states is limited to logarithmic depth in standard circuit models and existing constant-depth protocols require measurement and feed-forward. In this work, we present the first unitary, constant-depth protocols for exact Dicke state preparation. We overcome the loga… ▽ More Dicke states serve as a critical resource in quantum metrology, communication, and computation. However, unitary preparation of Dicke states is limited to logarithmic depth in standard circuit models and existing constant-depth protocols require measurement and feed-forward. In this work, we present the first unitary, constant-depth protocols for exact Dicke state preparation. We overcome the logarithmic-depth barrier by moving beyond the standard circuit model and leveraging global interactions (native to architectures such as neutral atoms and trapped ions). Specifically, utilizing unbounded CZ gates (i.e. within the QAC$^0$ circuit class), we offer circuits for exact computation of constant-weight Dicke states, using polynomial ancillae, and approximation of weight-1 Dicke states (i.e. $W$ states), using only constant ancillae. Granted additional access to the quantum FAN-OUT operation (i.e. upgrading to the QAC$_f^0$ circuit class), we also achieve exact and clean preparation of arbitrary-weight Dicke states, with polynomial ancillae. These protocols distinguish the constant-depth capabilities of quantum architectures based on connectivity and offer a novel path toward resolving a long-standing quantum complexity conjecture. △ Less

Submitted 20 March, 2026; v1 submitted 15 January, 2026; originally announced January 2026.

How Plasma Properties of the Fanaroff-Riley Jet can Shape its Morphology

Authors: Priyesh Kumar Tripathi, Indranil Chattopadhyay, Raj Kishor Joshi, Ritaban Chatterjee, Sanjit Debnath, M. Saleem Khan

Abstract: Extragalactic jets are broadly classified into two categories based on radio observations: core-brightened jets, known as Fanaroff-Riley Type I (FR I), and edge-brightened jets, classified as Type II (FR II). This FR dichotomy may arise due to variation in the ambient medium and/or the properties of the jet itself, such as injection speed, temperature, composition, magnetization, etc. To investiga… ▽ More Extragalactic jets are broadly classified into two categories based on radio observations: core-brightened jets, known as Fanaroff-Riley Type I (FR I), and edge-brightened jets, classified as Type II (FR II). This FR dichotomy may arise due to variation in the ambient medium and/or the properties of the jet itself, such as injection speed, temperature, composition, magnetization, etc. To investigate this, we perform large-scale three-dimensional magnetohydrodynamic (3D-MHD) simulations of low-power, supersonic jets extending to kiloparsec scales. We inject a jet beam carrying an initially toroidal magnetic field into a denser, unmagnetized, and stratified ambient medium through a cylindrical nozzle. Our simulations explore jets with varying injection parameters to investigate their impact on morphology and emission properties. Furthermore, we examine jets with significantly different plasma compositions, such as hadronic and mixed electron-positron-proton configurations, to study the conditions that may drive transitions between FR I and FR II morphologies. We find that, under the same injection parameters, mixed plasma composition jets tend to evolve into FR I structures. In contrast, electron-proton jets exhibit a transition between FR I and FR II morphologies at different stages of their evolution. △ Less

Submitted 14 January, 2026; originally announced January 2026.

Comments: Accepted for publication in ApJ, 15 pages, 1 table and 11 figures

Improved Lower Bounds for QAC0

Authors: Malvika Raj Joshi, Avishay Tal, Francisca Vasconcelos, John Wright

Abstract: In this work, we prove the strongest known lower bounds for QAC$^0$, allowing polynomially many gates and ancillae. Our main results show that: (1) Depth-3 QAC$^0$ circuits cannot compute PARITY, and require $Ω(\exp(\sqrt{n}))$ gates to compute MAJORITY. (2) Depth-2 circuits cannot approximate high-influence Boolean functions (e.g., PARITY) with non-negligible advantage, regardless of size.… ▽ More In this work, we prove the strongest known lower bounds for QAC$^0$, allowing polynomially many gates and ancillae. Our main results show that: (1) Depth-3 QAC$^0$ circuits cannot compute PARITY, and require $Ω(\exp(\sqrt{n}))$ gates to compute MAJORITY. (2) Depth-2 circuits cannot approximate high-influence Boolean functions (e.g., PARITY) with non-negligible advantage, regardless of size. We develop new classical simulation techniques for QAC$^0$ to obtain our depth-3 bounds. In these results, we relax the output requirement of the quantum circuit to a single bit, making our depth $2$ approximation bound stronger than the previous best bound of Rosenthal (2021). This also enables us to draw natural comparisons with classical AC$^0$ circuits, which can compute PARITY exactly in depth $2$ (exp size). Our techniques further suggest that, for boolean total functions, constant-depth quantum circuits do not necessarily provide more power than their classical counterparts. Our third result shows that depth $2$ QAC$^0$ circuits, regardless of size, cannot exactly synthesize an $n$-target nekomata state (a state whose synthesis is directly related to the computation of PARITY). This complements the depth $2$ exponential size upper bound of Rosenthal (2021) for approximating nekomatas (which is used as a sub-circuit in the only known constant depth PARITY upper bound). Finally, we argue that approximating PARITY in QAC0, with significantly better than 1/poly(n) advantage on average, is just as hard as computing it exactly. Thus, extending our techniques to higher depths would also rule out approximate circuits for PARITY and related problems △ Less

Submitted 20 January, 2026; v1 submitted 16 December, 2025; originally announced December 2025.

Magnetized transonic accretion disks

Authors: Raj Kishor Joshi, Antonios Tsokaros, Sanjit Debnath, Indranil Chattopadhyay, Ramiz Aktar

Abstract: Theoretical studies of transonic accretion onto black holes reveal a wide range of possible solutions, broadly classified into smooth flows and flows featuring shocks. Accretion solutions that involve the formation of shocks are particularly intriguing, as they are expected to naturally produce observable variability features. However, despite their theoretical significance, time-dependent studies… ▽ More Theoretical studies of transonic accretion onto black holes reveal a wide range of possible solutions, broadly classified into smooth flows and flows featuring shocks. Accretion solutions that involve the formation of shocks are particularly intriguing, as they are expected to naturally produce observable variability features. However, despite their theoretical significance, time-dependent studies exploring the stability and evolution of such shocked solutions remain relatively scarce. To address this gap, we perform simulations of transonic accretion flows around a black hole in ideal magneto-hydrodynamic framework. Our simulations are initialized using boundary conditions derived from semi-analytical hydrodynamical models, allowing us to explore the stability of these flows under varying magnetic field strengths. The presence of magnetic fields modifies the dynamics of the accretion flow through magnetic pressure, and the resulting force imbalance induces oscillations in the position of shock front. Our results show that variations in the emitted luminosity arising from shock oscillations appear as quasi-periodic oscillations (QPOs), a characteristic feature commonly observed in accreting black holes. We find that the QPO frequency is determined by the radial position of the shock front: oscillations occurring closer to the black hole produce frequencies of tens of hertz, whereas shocks located farther out yield sub-hertz frequencies △ Less

Submitted 13 December, 2025; originally announced December 2025.

Comments: Submitted to Universe SI: Mechanisms Behind Black Holes and Relativistic Jets

Endomorphisms of rank one Gorenstein del Pezzo surfaces

Authors: Rohan Joshi

Abstract: We prove that, in all except one case, a Gorenstein del Pezzo surface of Picard rank 1 admits an int-amplified endomorphism if and only if it is a quotient of a toric variety by a finite group which acts freely in codimension one and preserves the open torus. We classify all such quotients. We prove that, in all except one case, a Gorenstein del Pezzo surface of Picard rank 1 admits an int-amplified endomorphism if and only if it is a quotient of a toric variety by a finite group which acts freely in codimension one and preserves the open torus. We classify all such quotients. △ Less

Submitted 3 December, 2025; originally announced December 2025.

Active chromospheric fibril singularity: Coordinated observations from Solar Orbiter, SST, and IRIS

Authors: Reetika Joshi, Luc Rouppe van der Voort, Guillaume Aulanier, Sanja Danilovic, Avijeet Prasad, Carlos J. Díaz Baso, Daniel Nóbrega-Siverio, Nicolas Poirier, Daniele Calchetti

Abstract: The fine structures of the solar chromosphere, driven by photospheric motions, play a crucial role in the dynamics of solar magnetic fields. Many have been already identified such as fibrils, filament feet, and arch filament systems. Still, high resolution observations show a wealth of structures that remain elusive. We have observed a puzzling, unprecedented chromospheric fibril singularity in cl… ▽ More The fine structures of the solar chromosphere, driven by photospheric motions, play a crucial role in the dynamics of solar magnetic fields. Many have been already identified such as fibrils, filament feet, and arch filament systems. Still, high resolution observations show a wealth of structures that remain elusive. We have observed a puzzling, unprecedented chromospheric fibril singularity in close vicinity of a blow-out solar jet and a flaring loop. We aim to understand the magnetic nature of this singularity and the cause of its activity using coordinated high-resolution multi-wavelengths observations. We aligned datasets from Solar Orbiter, SST, IRIS, and SDO. We re-projected the Solar Orbiter datasets to match the perspective of the Earth-based instruments. We performed potential field extrapolations from Solar Orbiter/PHI data. We analysed the spatial and temporal evolution of the plasma structures and their link with the surface magnetic field. This leads us to derive a model and scenario for the observed structures which we explain in a general schematic representation. We have discovered a new feature, a singularity in the chromospheric fibril pattern. It is formed in a weak magnetic field corridor between two flux concentrations of equal sign, at the base of a vertically inverted-Y shape field line pattern. In this specific case some activity develops along the structure. Firstly a flaring loop at one end, secondly a blow-out jet at the other end, where a coronal null-point was present and associated with a chromospheric saddle point being located onto the fibril singularity. The observations sugge △ Less

Submitted 1 December, 2025; originally announced December 2025.

Comments: 6 pages, 5 figures, Accepted for publication in A&A

Journal ref: A&A 706, A369 (2026)

Health system learning achieves generalist neuroimaging models

Authors: Akhil Kondepudi, Akshay Rao, Chenhui Zhao, Yiwei Lyu, Samir Harake, Soumyanil Banerjee, Rushikesh Joshi, Anna-Katharina Meissner, Renly Hou, Cheng Jiang, Asadur Chowdury, Ashok Srinivasan, Brian Athey, Vikas Gulani, Aditya Pandey, Honglak Lee, Todd Hollon

Abstract: Frontier artificial intelligence (AI) models, such as OpenAI's GPT-5 and Meta's DINOv3, have advanced rapidly through training on internet-scale public data, yet such systems lack access to private clinical data. Neuroimaging, in particular, is underrepresented in the public domain due to identifiable facial features within MRI and CT scans, fundamentally restricting model performance in clinical… ▽ More Frontier artificial intelligence (AI) models, such as OpenAI's GPT-5 and Meta's DINOv3, have advanced rapidly through training on internet-scale public data, yet such systems lack access to private clinical data. Neuroimaging, in particular, is underrepresented in the public domain due to identifiable facial features within MRI and CT scans, fundamentally restricting model performance in clinical medicine. Here, we show that frontier models underperform on neuroimaging tasks and that learning directly from uncurated data generated during routine clinical care at health systems, a paradigm we call health system learning, yields high-performance, generalist neuroimaging models. We introduce NeuroVFM, a visual foundation model trained on 5.24 million clinical MRI and CT volumes using a scalable volumetric joint-embedding predictive architecture. NeuroVFM learns comprehensive representations of brain anatomy and pathology, achieving state-of-the-art performance across multiple clinical tasks, including radiologic diagnosis and report generation. The model exhibits emergent neuroanatomic understanding and interpretable visual grounding of diagnostic findings. When paired with open-source language models through lightweight visual instruction tuning, NeuroVFM generates radiology reports that surpass frontier models in accuracy, clinical triage, and expert preference. Through clinically grounded visual understanding, NeuroVFM reduces hallucinated findings and critical errors, offering safer clinical decision support. These results establish health system learning as a paradigm for building generalist medical AI and provide a scalable framework for clinical foundation models. △ Less

Submitted 23 November, 2025; originally announced November 2025.

Comments: 53 pages, 4 main figures, 10 extended data figures

Evidence for in-situ acceleration of relativistic particles in the wings of X-shaped radio galaxies

Authors: Dusmanta Patra, Gopal-Krishna, Ravi Joshi

Abstract: We report evidence for in-situ acceleration/re-acceleration of relativistic particles in 11 radio wings out of a total of 68 wings sufficiently well-resolved for spectral mapping, which belong to our sample of 40 X-shaped radio galaxies (XRGs). This representative XRG sample includes 15 XRGs newly reported here, which we selected from the LOTSS-DR2 survey, following well-defined criteria. The evid… ▽ More We report evidence for in-situ acceleration/re-acceleration of relativistic particles in 11 radio wings out of a total of 68 wings sufficiently well-resolved for spectral mapping, which belong to our sample of 40 X-shaped radio galaxies (XRGs). This representative XRG sample includes 15 XRGs newly reported here, which we selected from the LOTSS-DR2 survey, following well-defined criteria. The evidence for in-situ particle acceleration comes from the observed cessation of steepening, or even flattening (i.e., gradient reversal) of the spectral index profile along the lobe into the associated wing, as determined here by combining the LoTSS-DR2 (144 MHz) and FIRST (1.4 GHz) maps. Interestingly, the afore-mentioned trends in spectral gradient, indicative of in-situ particle acceleration, are mostly found to set in near the region where the lobe plasma stream bends to connect to the wing. Such a spatial coincidence with bending of radio lobe/tail has been noticed in recent years for just a couple of radio galaxies. The large increase in such examples, as reported here, is expected to give a fillip to observational, theoretical and numerical simulation follow-up investigations of this important clue about the occurrence of in-situ particle acceleration in lobes of radio galaxies. △ Less

Submitted 11 November, 2025; originally announced November 2025.

Comments: 7 Pages, 1 table, 1 Figure (Accepted for Publication in ApJ main Journal)

Prospects for a fourth generation of leptons in a 13 TeV p-p collider

Authors: Ramkrishna Joshi, Riddhiman Roy

Abstract: In the Standard Model, three discovered generations of leptons and quarks are known to date. However, speculations about existence of next generations have a strong foothold. In this study, we sequentially extrapolate the Standard Model to include a fourth generation of leptons (l4, nu4) with a massive Dirac neutrino. We perform MC simulated event generation of pp -> l4 l4(bar) scattering processe… ▽ More In the Standard Model, three discovered generations of leptons and quarks are known to date. However, speculations about existence of next generations have a strong foothold. In this study, we sequentially extrapolate the Standard Model to include a fourth generation of leptons (l4, nu4) with a massive Dirac neutrino. We perform MC simulated event generation of pp -> l4 l4(bar) scattering processes at an LHC-like p-p collider with sqrt(s) = 13 TeV by considering l4 mass of 190 GeV and nu4 mass of 100 GeV with PYTHIA. We demonstrate mass constraints of sequential leptons from oblique parameters and study important jet and lepton kinematics in our simulation with CMS like constraints. Fourth generation neutrino is stable in this scenario making l4 -> W nu4 the only dominant channel in collider searches. With the cut-flow, we achieve global excess of (1.46 +/- 0.068(stat.)) sigma and local excess of (3.33 +/- 0.241(stat.)) sigma in the 180-300 GeV signal window. Missing Transverse Energy (MET) provides clean signature of nu4. We assess discovery potential of the BSM lepton against lepton mass, center-of-mass energy (Ecom) and luminosities. Higher luminosities and Ecom are promising to probe BSM moderate mass lepton scenarios at present and future colliders. △ Less

Submitted 29 October, 2025; originally announced October 2025.

Comments: 16 pages,20 figures, 3 tables

Fine details in solar flare ribbons: Statistical insights from observations with the Swedish 1-m Solar Telescope

Authors: Jonas Thoen Faber, Reetika Joshi, Luc Rouppe van der Voort, Sven Wedemeyer, Eilif Sommer Øyre, Ignasi J. Soler Poquet, Aline Rangøy Brunvoll

Abstract: Flare ribbons serve as chromospheric footprints of energy deposition resulting from particle acceleration during magnetic reconnection. Their fine-scale structure provides a valuable tool for probing the dynamics of the flare reconnection process. Our goal is to investigate the fine-scale structure of flare ribbons through multiple observations of flares, utilising data obtained from the Atmospher… ▽ More Flare ribbons serve as chromospheric footprints of energy deposition resulting from particle acceleration during magnetic reconnection. Their fine-scale structure provides a valuable tool for probing the dynamics of the flare reconnection process. Our goal is to investigate the fine-scale structure of flare ribbons through multiple observations of flares, utilising data obtained from the Atmospheric Imaging Assembly (AIA) and the Swedish 1-m Solar Telescope (SST). The aligned AIA and SST datasets for the three solar flares were used to examine their overall morphology. The SST datasets were specifically used to identify fine-scale structures within the flare ribbons. For spectroscopic analysis of these fine structures, we applied machine-learning methods (k-means clustering) and Gaussian fitting. Using k-means, we identified elongated features in the flare ribbons, termed as "riblets", which are short-lived and jet-like small-scale structures that extend as plasma columns from the flare ribbons. Riblets are more prominent near the solar limb and represent the ribbon front. Riblet widths are consistent across observations, ranging from 110-310 km (0".15-0".41), while vertical lengths span 620-1220 km (0".83-1".66), with a potential maximum of 2000 km (2".67), after accounting for projection effects. Detailed H-beta spectral analysis reveals that riblets exhibit a single, redshifted emission component, with velocities of 16-21 km s^1, independent of viewing angle. Our high-resolution observations of the three flare ribbons show that they are not continuous structures, but are composed of vertically extended, fine-scale substructures. These irregular features indicate that the reconnection region is not a smooth, laminar current sheet, but rather a fragmented zone filled with magnetic islands, consistent with the theory of patchy reconnection within the coronal current sheet. △ Less

Submitted 27 October, 2025; originally announced October 2025.

Comments: 14 pages, 15 figures, accepted for publication in A&A

Journal ref: A&A 705, A174 (2026)

Circular sorting, strong complete mappings and wreath product constructions

Authors: Paul Bastide, Anurag Bishnoi, Carla Groenland, Dion Gijswijt, Rohinee Joshi

Abstract: We continue the study of Adin, Alon and Roichman [arXiv:2502.14398, 2025] on the number of steps required to sort $n$ labelled points on a circle by transpositions. Imagine that the vertices of a cycle of length $n$ are labelled by the elements $1,\dots,n$. We are allowed to change this labelling by swapping the labels of any two vertices on the cycle. How many swaps are needed to obtain a labelli… ▽ More We continue the study of Adin, Alon and Roichman [arXiv:2502.14398, 2025] on the number of steps required to sort $n$ labelled points on a circle by transpositions. Imagine that the vertices of a cycle of length $n$ are labelled by the elements $1,\dots,n$. We are allowed to change this labelling by swapping the labels of any two vertices on the cycle. How many swaps are needed to obtain a labelling that has the elements $1,\dots,n$ in clockwise order? We provide evidence for their conjecture that at most $n-3$ transpositions are needed to sort a circular permutation when $n$ is not prime. We prove this conjecture when $2\mid n$ or $3\mid n$ and when restricting to permutations given by a polynomial over $\mathbb{Z}_n$. We also provide various algebraic constructions of circular permutations that take many transpositions to sort, most notably providing one that matches our upper bound when $n=3p$ for $p$ an odd prime, and disproving their second conjecture by providing non-affine circular permutations that require $n-2$ transpositions (for $n$ prime). We also improve the lower bounds for some sequences of composite numbers. Finally, we improve the bounds for small $n$ computationally. In particular, we prove a tight upper bound for $n=25$ via an exhaustive computer search using a new connection between this problem and strong complete mappings. △ Less

Submitted 3 November, 2025; v1 submitted 21 October, 2025; originally announced October 2025.

Comments: 25 pages including references and appendices

Q-FSRU: Quantum-Augmented Frequency-Spectral For Medical Visual Question Answering

Authors: Rakesh Thakur, Yusra Tariq, Rakesh Chandra Joshi

Abstract: Solving tough clinical questions that require both image and text understanding is still a major challenge in healthcare AI. In this work, we propose Q-FSRU, a new model that combines Frequency Spectrum Representation and Fusion (FSRU) with a method called Quantum Retrieval-Augmented Generation (Quantum RAG) for medical Visual Question Answering (VQA). The model takes in features from medical imag… ▽ More Solving tough clinical questions that require both image and text understanding is still a major challenge in healthcare AI. In this work, we propose Q-FSRU, a new model that combines Frequency Spectrum Representation and Fusion (FSRU) with a method called Quantum Retrieval-Augmented Generation (Quantum RAG) for medical Visual Question Answering (VQA). The model takes in features from medical images and related text, then shifts them into the frequency domain using Fast Fourier Transform (FFT). This helps it focus on more meaningful data and filter out noise or less useful information. To improve accuracy and ensure that answers are based on real knowledge, we add a quantum inspired retrieval system. It fetches useful medical facts from external sources using quantum-based similarity techniques. These details are then merged with the frequency-based features for stronger reasoning. We evaluated our model using the VQA-RAD dataset, which includes real radiology images and questions. The results showed that Q-FSRU outperforms earlier models, especially on complex cases needing image text reasoning. The mix of frequency and quantum information improves both performance and explainability. Overall, this approach offers a promising way to build smart, clear, and helpful AI tools for doctors. △ Less

Submitted 2 October, 2025; v1 submitted 28 September, 2025; originally announced September 2025.

Comments: 12 pages (9 main + 2 references/appendix), 2 figures, conference paper submitted to ICLR 2026

Dynamical properties of oscillating, viscous, transonic accretion disks around black holes

Authors: Sanjit Debnath, Indranil Chattopadhyay, Raj Kishor Joshi, Philippe Laurent, Priyesh Kumar Tripathi, M. Saleem Khan

Abstract: We investigate the time evolution of sub-Keplerian transonic accretion flow onto a non-rotating black hole using axisymmetric viscous hydrodynamic simulations. We simulate the accretion flow using boundary values from semi-analytical analysis and set up three different models. Two of the models do not predict accretion shocks from the semi-analytic analysis, while one of them does. We also conside… ▽ More We investigate the time evolution of sub-Keplerian transonic accretion flow onto a non-rotating black hole using axisymmetric viscous hydrodynamic simulations. We simulate the accretion flow using boundary values from semi-analytical analysis and set up three different models. Two of the models do not predict accretion shocks from the semi-analytic analysis, while one of them does. We also consider radiative cooling along with viscosity in the simulation. Our two-dimensional simulation deviated from the one-dimensional semi-analytical solution and admitted shocks in all three models. Viscous dissipation tends to push the shock front outward, and radiative cooling will push it in. Additionally, gravity is attractive. Depending on the competing strengths of all three processes, it may trigger shock oscillation. Different rates of angular-momentum transport in various layers may trigger eddies, which will enhance the shock oscillation. We show that any simple power law cannot approximate these solutions. We find that hot and higher angular-momentum flow requires higher viscosity to produce oscillatory shocks. From the temporal variation of the luminosity, shock oscillations generate QPOs in the range of sub-Hertz to a few Hertz frequencies if a ten solar mass black hole is assumed. △ Less

Submitted 24 September, 2025; originally announced September 2025.

Comments: Accepted for publication in ApJ, 15 pages, 9 figures

Learning neuroimaging models from health system-scale data

Authors: Yiwei Lyu, Samir Harake, Asadur Chowdury, Soumyanil Banerjee, Rachel Gologorsky, Shixuan Liu, Anna-Katharina Meissner, Akshay Rao, Chenhui Zhao, Akhil Kondepudi, Cheng Jiang, Xinhai Hou, Rushikesh S. Joshi, Volker Neuschmelting, Ashok Srinivasan, Dawn Kleindorfer, Brian Athey, Vikas Gulani, Aditya Pandey, Honglak Lee, Todd Hollon

Abstract: Neuroimaging is a ubiquitous tool for evaluating patients with neurological diseases. The global demand for magnetic resonance imaging (MRI) studies has risen steadily, placing significant strain on health systems, prolonging turnaround times, and intensifying physician burnout. These challenges disproportionately impact patients in low-resource and rural settings. Here, we utilized a large academ… ▽ More Neuroimaging is a ubiquitous tool for evaluating patients with neurological diseases. The global demand for magnetic resonance imaging (MRI) studies has risen steadily, placing significant strain on health systems, prolonging turnaround times, and intensifying physician burnout. These challenges disproportionately impact patients in low-resource and rural settings. Here, we utilized a large academic health system as a data engine to develop Prima, the first vision language model (VLM) serving as an AI foundation for neuroimaging that supports real-world, clinical MRI studies as input. Trained on over 220,000 MRI studies, Prima uses a hierarchical vision architecture that provides general and transferable MRI features. Prima was tested in a 1-year health system-wide study that included 30K MRI studies. Across 52 radiologic diagnoses from the major neurologic disorders, including neoplastic, inflammatory, infectious, and developmental lesions, Prima achieved a mean diagnostic area under the ROC curve of 92.0, outperforming other state-of-the-art general and medical AI models. Prima offers explainable differential diagnoses, worklist priority for radiologists, and clinical referral recommendations across diverse patient demographics and MRI systems. Prima demonstrates algorithmic fairness across sensitive groups and can help mitigate health system biases, such as prolonged turnaround times for low-resource populations. These findings highlight the transformative potential of health system-scale VLMs and Prima's role in advancing AI-driven healthcare. △ Less

Submitted 15 December, 2025; v1 submitted 23 September, 2025; originally announced September 2025.

Single-Cell Universal Logic-in-Memory Using 2T-nC FeRAM: An Area and Energy-Efficient Approach for Bulk Bitwise Computation

Authors: Rudra Biswas, Jiahui Duan, Shan Deng, Xuezhong Niu, Yixin Qin, Prapti Panigrahi, Varun Parekh, Rajiv Joshi, Kai Ni, Vijaykrishnan Narayanan

Abstract: This work presents a novel approach to configure 2T-nC ferroelectric RAM (FeRAM) for performing single cell logic-in-memory operations, highlighting its advantages in energy-efficient computation over conventional DRAM-based approaches. Unlike conventional 1T-1C dynamic RAM (DRAM), which incurs refresh overhead, 2T-nC FeRAM offers a promising alternative as a non-volatile memory solution with low… ▽ More This work presents a novel approach to configure 2T-nC ferroelectric RAM (FeRAM) for performing single cell logic-in-memory operations, highlighting its advantages in energy-efficient computation over conventional DRAM-based approaches. Unlike conventional 1T-1C dynamic RAM (DRAM), which incurs refresh overhead, 2T-nC FeRAM offers a promising alternative as a non-volatile memory solution with low energy consumption. Our key findings include the potential of quasi-nondestructive readout (QNRO) sensing in 2T-nC FeRAM for logic-in-memory (LiM) applications, demonstrating its inherent capability to perform inverting logic without requiring external modifications, a feature absent in traditional 1T-1C DRAM. We successfully implement the MINORITY function within a single cell of 2T-nC FeRAM, enabling universal NAND and NOR logic, validated through SPICE simulations and experimental data. Additionally, the research investigates the feasibility of 3D integration with 2T-nC FeRAM, showing substantial improvements in storage and computational density, facilitating bulk-bitwise computation. Our evaluation of eight real-world, data-intensive applications reveals that 2T-nC FeRAM achieves 2x higher performance and 2.5x lower energy consumption compared to DRAM. Furthermore, the thermal stability of stacked 2T-nC FeRAM is validated, confirming its reliable operation when integrated on a compute die. These findings emphasize the advantages of 2T-nC FeRAM for LiM, offering superior performance and energy efficiency over conventional DRAM. △ Less

Submitted 22 September, 2025; originally announced September 2025.

Comments: 6 Pages, 7 Figures, To be presented at System on Chip Conference 2025

ShadowServe: Interference-Free KV Cache Fetching for Distributed Prefix Caching

Authors: Xingyu Xiang, Raj Joshi, Yuhan Liu, Jiayi Yao, Chenxingyu Zhao, Junchen Jiang, Yang Zhou, Eddie Kohler, Minlan Yu

Abstract: Distributed prefix caching accelerates long-context LLM serving by reusing KV cache entries for common context prefixes. However, KV cache fetches can become a bottleneck when network bandwidth is limited. Compression mitigates the bandwidth issue, but can degrade overall performance when decompression interferes with model computation. We present ShadowServe, the first SmartNIC-accelerated, int… ▽ More Distributed prefix caching accelerates long-context LLM serving by reusing KV cache entries for common context prefixes. However, KV cache fetches can become a bottleneck when network bandwidth is limited. Compression mitigates the bandwidth issue, but can degrade overall performance when decompression interferes with model computation. We present ShadowServe, the first SmartNIC-accelerated, interference-free prefix caching system for LLM serving. ShadowServe separates a control plane on the host and a data plane fully offloaded to the SmartNIC, which eliminates interference to both host GPU and CPU. To overcome the SmartNIC's limited compute and memory resources, we design a chunked pipeline that parallelizes data plane operations across the SmartNIC's compute resources, and a minimal-copy memory management scheme that reduces memory pressure on the SmartNIC. Compared to state-of-the-art solutions, ShadowServe achieves up to 2.2x lower loaded time-per-output-token (TPOT), and reduces time-to-first-token (TTFT) by up to 1.38x in low-bandwidth scenarios (<= 20 Gbps), translating to up to 1.35x higher throughput. △ Less

Submitted 20 September, 2025; originally announced September 2025.

Binary black holes in magnetized AGN disks

Authors: Raj Kishor Joshi, Aryan Bhake, Biswajit Banerjee, Bhargav Vaidya, Milton Ruiz, Antonios Tsokaros, Andrea Mignone, Marica Branchesi, Amit Shukla, Miljenko Čemeljić

Abstract: Stellar-mass binary black hole (BBH) mergers occurring within the disks of active galactic nuclei (AGN) are promising sources for gravitational waves detectable by the LIGO, Virgo, and KAGRA (LVK) interferometers. Some of these events have also been potentially associated with transient electromagnetic flares, indicating that BBH mergers in dense environments may be promising sources of multi-mess… ▽ More Stellar-mass binary black hole (BBH) mergers occurring within the disks of active galactic nuclei (AGN) are promising sources for gravitational waves detectable by the LIGO, Virgo, and KAGRA (LVK) interferometers. Some of these events have also been potentially associated with transient electromagnetic flares, indicating that BBH mergers in dense environments may be promising sources of multi-messenger signals. To investigate the prospects for electromagnetic emission from these systems, we study the dynamics of accretion flows onto BBHs embedded in AGN disks using numerical simulations. Although recent studies have explored this scenario, they often employ simplified disk models that neglect magnetic fields. In this work, we examine how strong magnetic fields influence and regulate the accretion onto such binary systems. In this context, we conduct three-dimensional magnetohydrodynamical local shearing-box simulations of a binary black hole system embedded within a magnetized disk of an AGN. We observe that the dynamically important magnetic fields can drive the formation of well-collimated outflows capable of penetrating the vertical extent of the AGN disk. However, outflow generation is not ubiquitous and strongly depends on the radial distance of the binary from the supermassive black hole (SMBH). In particular, binaries placed at a larger distance from the central SMBH show relatively more transient accretion and the formation of stronger spiral shocks. Furthermore, accretion behavior onto the binary system via individual circum-singular disks (CSDs) is also modulated by local AGN disk properties. Our simulations highlight the importance of shear velocity in the amplification of the toroidal magnetic field component, which plays a crucial role in governing the outflow strength. △ Less

Submitted 20 September, 2025; originally announced September 2025.

Comments: Accepted for publication in A&A

Journal ref: A&A 703, A304 (2025)

Revisiting the ARM cut in Compton gamma-ray imaging and its application to the INSPIRE detector

Authors: J. Kataoka, S. Ogasawara, R. Mori, K. Yamamoto, A. R. Joshi, S. Kojima, K. Sato, K. S. Tanaka, K. Watanabe, M. Yasuda, H. Kobayashi, D. Kobayashi, A. Ohira, Y. Amaki, Y. Arai, K. Tashirio, K. Otsubo, Y. Ozeki, Y. Kawaguchi, D. Yoshimura, H. Yoshida, K. Takahashi, S. Masaki, N. Yamada, K. Oikawa , et al. (10 additional authors not shown)

Abstract: The Compton camera is a gamma-ray imaging device developed in the 1970s. In the 1990s, the COMPTEL detector onboard the CGRO was the first to utilize a Compton camera for MeV all-sky survey observations. Recently, various Compton cameras have been developed using scintillators, semiconductors, and gas detectors, some of which are intended for future small satellite missions as well as medical appl… ▽ More The Compton camera is a gamma-ray imaging device developed in the 1970s. In the 1990s, the COMPTEL detector onboard the CGRO was the first to utilize a Compton camera for MeV all-sky survey observations. Recently, various Compton cameras have been developed using scintillators, semiconductors, and gas detectors, some of which are intended for future small satellite missions as well as medical applications. However, the image obtained by a Compton camera has strong artifacts owing to the overlap of the Compton cones or the arcs, which degrade the resolution and sensitivity of the image. In this study, we revisit the adaptive ARM cut that significantly reduces artifacts when the direction of gamma ray emitting source is already known. This approach complements the statistically well-defined method based on the response function in the three-dimensional data space of scattering direction (χ, ψ) and scattering angle θ, but it is more direct, intuitive, and simplifies the extraction of spectra in astronomical observations of point-like sources. Using a Compton camera, INSPIRE, onboard the ultra-small satellite GRAPHIUM as an example, we numerically evaluated the extent of background reduction to estimate simulation-based sensitivity. The method was also applied to actual measurements using a quarter-scale prototype of INSPIRE to extract spectra from multiple sources within the same field of view. △ Less

Submitted 17 September, 2025; originally announced September 2025.

Comments: 18 pages, 13 figures, accepted for publication in the Journal of Instrumentation

Origin of the double-peaked narrow emission-lines in the optical spectra of X-shaped Radio Galaxies

Authors: Prajnadipt Ghosh, Ravi Joshi, Xiaolong Yang, Yingkang Zhang, Gopal-Krishna, Paul J. Wiita, Ankit Patel, Arti Goyal, Gourab Giri, Santanu Mondal, Vibhore Negi, Marek Wezgowiec, Xue-Bing Wu, Luis C. Ho

Abstract: We investigate the X-shaped radio galaxies (XRGs) with optical double-peaked narrow emission (DPNEL) as potential hosts of dual or binary supermassive black holes (SMBHs). Using a sample of 187 XRGs selected from SDSS and DESI optical spectroscopic surveys, we check the AGN nature of both emission components using the BPT diagnostics of multiple emission lines, namely {[O III]$λλ$4959,5007}, H$α$,… ▽ More We investigate the X-shaped radio galaxies (XRGs) with optical double-peaked narrow emission (DPNEL) as potential hosts of dual or binary supermassive black holes (SMBHs). Using a sample of 187 XRGs selected from SDSS and DESI optical spectroscopic surveys, we check the AGN nature of both emission components using the BPT diagnostics of multiple emission lines, namely {[O III]$λλ$4959,5007}, H$α$, {[N II]$λλ$6548,6584}, {[S II]$λλ$6716,6731}, and H$β$, and mid-infrared colors. We find that the detection rate of [O III] DPNEL features in XRGs is 30% compared to just 1% in the general galaxy population (mostly radio quiet). The dual AGN fraction in DPNEL galaxies is found to depend strongly on the radio luminosity, increasing from $\sim$25% for radio-undetected to $\sim$58% in the radio-detected sample of general DPNEL galaxies. In contrast, the DPNEL XRGs and FR-II radio galaxies having higher radio power show a $\sim$95% likelihood of hosting a dual AGN. Secondly, the detection of companion galaxies in more than 30% of DPNEL XRGs suggests a vital role of mergers in the XRG formation. We also investigate the parsec-scale radio structure of the nuclei of several XRGs using Very Long Baseline Array (VLBA) maps at 1.4 GHz, 4.3 GHz or 7.6 GHz and find a resolved core for only one of the XRGs. However, the flat spectral indices of the VLBA cores along with the DPNEL components exhibiting AGN characteristics, together with the detection of radio-optical offsets between the VLBA and Gaia position, are strongly indicative of XRGs being likely candidates for hosting dual/binary AGNs. △ Less

Submitted 15 September, 2025; originally announced September 2025.

Comments: 17 Pages, 8 Figures, submitted to ApJ

Baryonic Ecosystem IN Galaxies (BEINGMgII) -- III. Cool gas reservoirs at $0.3 \le z \le 1.6$ in the Dark Energy Survey

Authors: Reena Chaudhary, Ravi Joshi, Sarbeswar Das, Michele Fumagalli, Glenn G. Kacprzak, Matteo Fossati, Celine Péroux, Luis C. Ho

Abstract: We investigate the origin of intervening cool MgII absorption detected in the spectra of background quasars and the nature of associated galaxies across a broad redshift range of $0.3 \le z \le 1.6$. Using nebular [O II] $λλ$3727,3729 emission lines identified in DESI fiber spectra centered on quasar, we detect 377 galaxies at a typical detection rate of $\sim$0.45% at $z \lesssim 1$, which increa… ▽ More We investigate the origin of intervening cool MgII absorption detected in the spectra of background quasars and the nature of associated galaxies across a broad redshift range of $0.3 \le z \le 1.6$. Using nebular [O II] $λλ$3727,3729 emission lines identified in DESI fiber spectra centered on quasar, we detect 377 galaxies at a typical detection rate of $\sim$0.45% at $z \lesssim 1$, which increases with MgII equivalent width ($W_{2796}$). A significant fraction (74%) of these galaxies are associated with strong absorbers with $W_{2796} \ge$ 2Å. These absorbers trace galaxies spanning stellar masses of $\rm 8.4 \le \log(M_{\star}/M_{\odot}) \le 11.6$ and star formation rates (SFRs) of $\rm -1.2 \le log(SFR~[M_{\odot}yr^{-1}]) \le 2.7$, located at projected galactocentric distances of 4-24 kpc. We find the average MgII absorber strength increases from 2.1Å to 2.9Å between redshifts $z \sim$ 0.4 and 1.2, indicating evolution in the cool gas content of galaxy halos. The relatively constant absorber strength with galactocentric distance implies a clumpy structure of cool gas in the circumgalactic medium (CGM). Further, we find a positive correlation between $W_{2796}$ versus $M_\star$, and SFR, suggesting that the distribution of metal-enriched cool gas in the CGM is closely tied to the properties of the host galaxies. The redshift evolution of gas-phase metallicity suggests that strong MgII absorbers trace the general population of star-forming galaxies. The velocity dispersion of the cool gas increases with halo mass, and the wide range of line of sight velocity offset (-389 to 364 $\rm km\ s^{-1}$) between the galaxy systemic velocity and absorbers highlights the dynamical nature of CGM. However, the majority of this gas remains gravitationally bound to the dark matter halos, consistent with a picture of gas recycling via galactic fountains. △ Less

Submitted 2 September, 2025; originally announced September 2025.

Comments: 11 pages, 8 figures, submitted to A&A

Comparative Study of Pre-Trained BERT and Large Language Models for Code-Mixed Named Entity Recognition

Authors: Mayur Shirke, Amey Shembade, Pavan Thorat, Madhushri Wagh, Raviraj Joshi

Abstract: Named Entity Recognition (NER) in code-mixed text, particularly Hindi-English (Hinglish), presents unique challenges due to informal structure, transliteration, and frequent language switching. This study conducts a comparative evaluation of code-mixed fine-tuned models and non-code-mixed multilingual models, along with zero-shot generative large language models (LLMs). Specifically, we evaluate H… ▽ More Named Entity Recognition (NER) in code-mixed text, particularly Hindi-English (Hinglish), presents unique challenges due to informal structure, transliteration, and frequent language switching. This study conducts a comparative evaluation of code-mixed fine-tuned models and non-code-mixed multilingual models, along with zero-shot generative large language models (LLMs). Specifically, we evaluate HingBERT, HingMBERT, and HingRoBERTa (trained on code-mixed data), and BERT Base Cased, IndicBERT, RoBERTa and MuRIL (trained on non-code-mixed multilingual data). We also assess the performance of Google Gemini in a zero-shot setting using a modified version of the dataset with NER tags removed. All models are tested on a benchmark Hinglish NER dataset using Precision, Recall, and F1-score. Results show that code-mixed models, particularly HingRoBERTa and HingBERT-based fine-tuned models, outperform others - including closed-source LLMs like Google Gemini - due to domain-specific pretraining. Non-code-mixed models perform reasonably but show limited adaptability. Notably, Google Gemini exhibits competitive zero-shot performance, underlining the generalization strength of modern LLMs. This study provides key insights into the effectiveness of specialized versus generalized models for code-mixed NER tasks. △ Less

Submitted 2 September, 2025; originally announced September 2025.

L3Cube-IndicHeadline-ID: A Dataset for Headline Identification and Semantic Evaluation in Low-Resource Indian Languages

Authors: Nishant Tanksale, Tanmay Kokate, Darshan Gohad, Sarvadnyaa Barate, Raviraj Joshi

Abstract: Semantic evaluation in low-resource languages remains a major challenge in NLP. While sentence transformers have shown strong performance in high-resource settings, their effectiveness in Indic languages is underexplored due to a lack of high-quality benchmarks. To bridge this gap, we introduce L3Cube-IndicHeadline-ID, a curated headline identification dataset spanning ten low-resource Indic langu… ▽ More Semantic evaluation in low-resource languages remains a major challenge in NLP. While sentence transformers have shown strong performance in high-resource settings, their effectiveness in Indic languages is underexplored due to a lack of high-quality benchmarks. To bridge this gap, we introduce L3Cube-IndicHeadline-ID, a curated headline identification dataset spanning ten low-resource Indic languages: Marathi, Hindi, Tamil, Gujarati, Odia, Kannada, Malayalam, Punjabi, Telugu, Bengali and English. Each language includes 20,000 news articles paired with four headline variants: the original, a semantically similar version, a lexically similar version, and an unrelated one, designed to test fine-grained semantic understanding. The task requires selecting the correct headline from the options using article-headline similarity. We benchmark several sentence transformers, including multilingual and language-specific models, using cosine similarity. Results show that multilingual models consistently perform well, while language-specific models vary in effectiveness. Given the rising use of similarity models in Retrieval-Augmented Generation (RAG) pipelines, this dataset also serves as a valuable resource for evaluating and improving semantic understanding in such applications. Additionally, the dataset can be repurposed for multiple-choice question answering, headline classification, or other task-specific evaluations of LLMs, making it a versatile benchmark for Indic NLP. The dataset is shared publicly at https://github.com/l3cube-pune/indic-nlp △ Less

Submitted 2 September, 2025; originally announced September 2025.

L3Cube-MahaSTS: A Marathi Sentence Similarity Dataset and Models

Authors: Aishwarya Mirashi, Ananya Joshi, Raviraj Joshi

Abstract: We present MahaSTS, a human-annotated Sentence Textual Similarity (STS) dataset for Marathi, along with MahaSBERT-STS-v2, a fine-tuned Sentence-BERT model optimized for regression-based similarity scoring. The MahaSTS dataset consists of 16,860 Marathi sentence pairs labeled with continuous similarity scores in the range of 0-5. To ensure balanced supervision, the dataset is uniformly distributed… ▽ More We present MahaSTS, a human-annotated Sentence Textual Similarity (STS) dataset for Marathi, along with MahaSBERT-STS-v2, a fine-tuned Sentence-BERT model optimized for regression-based similarity scoring. The MahaSTS dataset consists of 16,860 Marathi sentence pairs labeled with continuous similarity scores in the range of 0-5. To ensure balanced supervision, the dataset is uniformly distributed across six score-based buckets spanning the full 0-5 range, thus reducing label bias and enhancing model stability. We fine-tune the MahaSBERT model on this dataset and benchmark its performance against other alternatives like MahaBERT, MuRIL, IndicBERT, and IndicSBERT. Our experiments demonstrate that MahaSTS enables effective training for sentence similarity tasks in Marathi, highlighting the impact of human-curated annotations, targeted fine-tuning, and structured supervision in low-resource settings. The dataset and model are publicly shared at https://github.com/l3cube-pune/MarathiNLP △ Less

Submitted 29 August, 2025; originally announced August 2025.

Benchmarking Hindi LLMs: A New Suite of Datasets and a Comparative Analysis

Authors: Anusha Kamath, Kanishk Singla, Rakesh Paul, Raviraj Joshi, Utkarsh Vaidya, Sanjay Singh Chauhan, Niranjan Wartikar

Abstract: Evaluating instruction-tuned Large Language Models (LLMs) in Hindi is challenging due to a lack of high-quality benchmarks, as direct translation of English datasets fails to capture crucial linguistic and cultural nuances. To address this, we introduce a suite of five Hindi LLM evaluation datasets: IFEval-Hi, MT-Bench-Hi, GSM8K-Hi, ChatRAG-Hi, and BFCL-Hi. These were created using a methodology t… ▽ More Evaluating instruction-tuned Large Language Models (LLMs) in Hindi is challenging due to a lack of high-quality benchmarks, as direct translation of English datasets fails to capture crucial linguistic and cultural nuances. To address this, we introduce a suite of five Hindi LLM evaluation datasets: IFEval-Hi, MT-Bench-Hi, GSM8K-Hi, ChatRAG-Hi, and BFCL-Hi. These were created using a methodology that combines from-scratch human annotation with a translate-and-verify process. We leverage this suite to conduct an extensive benchmarking of open-source LLMs supporting Hindi, providing a detailed comparative analysis of their current capabilities. Our curation process also serves as a replicable methodology for developing benchmarks in other low-resource languages. △ Less

Submitted 15 October, 2025; v1 submitted 27 August, 2025; originally announced August 2025.

Efficient Zero-Shot Long Document Classification by Reducing Context Through Sentence Ranking

Authors: Prathamesh Kokate, Mitali Sarnaik, Manavi Khopade, Mukta Takalikar, Raviraj Joshi

Abstract: Transformer-based models like BERT excel at short text classification but struggle with long document classification (LDC) due to input length limitations and computational inefficiencies. In this work, we propose an efficient, zero-shot approach to LDC that leverages sentence ranking to reduce input context without altering the model architecture. Our method enables the adaptation of models train… ▽ More Transformer-based models like BERT excel at short text classification but struggle with long document classification (LDC) due to input length limitations and computational inefficiencies. In this work, we propose an efficient, zero-shot approach to LDC that leverages sentence ranking to reduce input context without altering the model architecture. Our method enables the adaptation of models trained on short texts, such as headlines, to long-form documents by selecting the most informative sentences using a TF-IDF-based ranking strategy. Using the MahaNews dataset of long Marathi news articles, we evaluate three context reduction strategies that prioritize essential content while preserving classification accuracy. Our results show that retaining only the top 50\% ranked sentences maintains performance comparable to full-document inference while reducing inference time by up to 35\%. This demonstrates that sentence ranking is a simple yet effective technique for scalable and efficient zero-shot LDC. △ Less

Submitted 24 August, 2025; originally announced August 2025.

MahaParaphrase: A Marathi Paraphrase Detection Corpus and BERT-based Models

Authors: Suramya Jadhav, Abhay Shanbhag, Amogh Thakurdesai, Ridhima Sinare, Ananya Joshi, Raviraj Joshi

Abstract: Paraphrases are a vital tool to assist language understanding tasks such as question answering, style transfer, semantic parsing, and data augmentation tasks. Indic languages are complex in natural language processing (NLP) due to their rich morphological and syntactic variations, diverse scripts, and limited availability of annotated data. In this work, we present the L3Cube-MahaParaphrase Datase… ▽ More Paraphrases are a vital tool to assist language understanding tasks such as question answering, style transfer, semantic parsing, and data augmentation tasks. Indic languages are complex in natural language processing (NLP) due to their rich morphological and syntactic variations, diverse scripts, and limited availability of annotated data. In this work, we present the L3Cube-MahaParaphrase Dataset, a high-quality paraphrase corpus for Marathi, a low resource Indic language, consisting of 8,000 sentence pairs, each annotated by human experts as either Paraphrase (P) or Non-paraphrase (NP). We also present the results of standard transformer-based BERT models on these datasets. The dataset and model are publicly shared at https://github.com/l3cube-pune/MarathiNLP △ Less

Submitted 24 August, 2025; originally announced August 2025.

Parity Cross-Resonance: A Multiqubit Gate

Authors: Xuexin Xu, Siyu Wang, Radhika Joshi, Rihan Hai, Mohammad H. Ansari

Abstract: We present a native three-qubit entangling gate that exploits engineered interactions to realize control-control-target and control-target-target operations in a single coherent step. Unlike conventional decompositions into multiple two-qubit gates, our hybrid optimization approach selectively amplifies desired interactions while suppressing unwanted couplings, yielding robust performance across t… ▽ More We present a native three-qubit entangling gate that exploits engineered interactions to realize control-control-target and control-target-target operations in a single coherent step. Unlike conventional decompositions into multiple two-qubit gates, our hybrid optimization approach selectively amplifies desired interactions while suppressing unwanted couplings, yielding robust performance across the computational subspace and beyond. The new gate can be classified as a cross-resonance gate. We show it can be utilized in several ways, for example, in GHZ triplet state preparation, Toffoli-class logic demonstrations with many-body interactions, and in implementing a controlled-ZZ gate. The latter maps the parity of two data qubits directly onto a measurement qubit, enabling faster and higher-fidelity stabilizer measurements in surface-code quantum error correction. In all these examples, we show that the three-qubit gate performance remains robust across Hilbert space sizes, as confirmed by testing under increasing total excitation numbers. This work lays the foundation for co-designing circuit architectures and control protocols that leverage native multiqubit interactions as core elements of next-generation superconducting quantum processors. △ Less

Submitted 14 August, 2025; originally announced August 2025.

Comments: 19 pages, 10 figures

Information Transport in Classical-Quantum Hybrid System

Authors: Julian Rapp, Radhika H. Joshi, Alwin van Steensel, Yuli V. Nazarov, Mohammad H. Ansari

Abstract: Many important quantities in quantum information science, such as entropy and entanglement, are non-linear functions of the density matrix and cannot be expressed as operator observables. Standard open-system approaches evolve only a single copy of the density matrix, making it impossible to track the dynamics of such quantities. A formalism proposed by some of the present authors addressed this c… ▽ More Many important quantities in quantum information science, such as entropy and entanglement, are non-linear functions of the density matrix and cannot be expressed as operator observables. Standard open-system approaches evolve only a single copy of the density matrix, making it impossible to track the dynamics of such quantities. A formalism proposed by some of the present authors addressed this challenge by evolving multiple virtual replicas, but was limited to the weak-coupling regime. Here, we extend this approach to strong coupling between a quantum system and classical environments. The resulting multi-replica master equation enables direct evaluation of entropy flow and related metrics in strongly hybridized quantum-classical systems. Our results show that quantum coherence and hybridization jointly suppress net entropy transfer, creating a thermodynamic bottleneck. This framework provides a general tool for studying entropy dynamics and guiding the design of more robust, resource-efficient quantum hardware. △ Less

Submitted 18 August, 2025; v1 submitted 11 August, 2025; originally announced August 2025.

Comments: 16 pages, 11 figures, References updated

CultureGuard: Towards Culturally-Aware Dataset and Guard Model for Multilingual Safety Applications

Authors: Raviraj Joshi, Rakesh Paul, Kanishk Singla, Anusha Kamath, Michael Evans, Katherine Luna, Shaona Ghosh, Utkarsh Vaidya, Eileen Long, Sanjay Singh Chauhan, Niranjan Wartikar

Abstract: The increasing use of Large Language Models (LLMs) in agentic applications highlights the need for robust safety guard models. While content safety in English is well-studied, non-English languages lack similar advancements due to the high cost of collecting culturally aligned labeled datasets. We present CultureGuard, a novel solution for curating culturally aligned, high-quality safety datasets… ▽ More The increasing use of Large Language Models (LLMs) in agentic applications highlights the need for robust safety guard models. While content safety in English is well-studied, non-English languages lack similar advancements due to the high cost of collecting culturally aligned labeled datasets. We present CultureGuard, a novel solution for curating culturally aligned, high-quality safety datasets across multiple languages. Our approach introduces a four-stage synthetic data generation and filtering pipeline: cultural data segregation, cultural data adaptation, machine translation, and quality filtering. This pipeline enables the conversion and expansion of the Nemotron-Content-Safety-Dataset-V2 English safety dataset into eight distinct languages: Arabic, German, Spanish, French, Hindi, Japanese, Thai, and Chinese. The resulting dataset, Nemotron-Safety-Guard-Dataset-v3, comprises 386,661 samples in 9 languages and facilitates the training of Llama-3.1-Nemotron-Safety-Guard-8B-v3 via LoRA-based fine-tuning. The final model achieves state-of-the-art performance on several multilingual content safety benchmarks. Furthermore, we show our moderately multilingual fine-tuning enables robust cross-lingual transfer and strong zero-shot generalization to unseen languages. We also benchmark the latest open LLMs on multilingual safety and observe that these LLMs are more prone to give unsafe responses when prompted in non-English languages. This work advances multilingual LLM safety by enabling the development of culturally aware safety guard models. △ Less

Submitted 9 November, 2025; v1 submitted 3 August, 2025; originally announced August 2025.

Aligning Large Language Models to Low-Resource Languages through LLM-Based Selective Translation: A Systematic Study

Authors: Rakesh Paul, Anusha Kamath, Kanishk Singla, Raviraj Joshi, Utkarsh Vaidya, Sanjay Singh Chauhan, Niranjan Wartikar

Abstract: Multilingual large language models (LLMs) often demonstrate a performance gap between English and non-English languages, particularly in low-resource settings. Aligning these models to low-resource languages is essential yet challenging due to limited high-quality data. While English alignment datasets are readily available, curating equivalent data in other languages is expensive and time-consumi… ▽ More Multilingual large language models (LLMs) often demonstrate a performance gap between English and non-English languages, particularly in low-resource settings. Aligning these models to low-resource languages is essential yet challenging due to limited high-quality data. While English alignment datasets are readily available, curating equivalent data in other languages is expensive and time-consuming. A common workaround is to translate existing English alignment data; however, standard translation techniques often fail to preserve critical elements such as code, mathematical expressions, and structured formats like JSON. In this work, we investigate LLM-based selective translation, a technique that selectively translates only the translatable parts of a text while preserving non-translatable content and sentence structure. We conduct a systematic study to explore key questions around this approach, including its effectiveness compared to vanilla translation, the importance of filtering noisy outputs, and the benefits of mixing translated samples with original English data during alignment. Our experiments focus on the low-resource Indic language Hindi and compare translations generated by Google Cloud Translation (GCP) and Llama-3.1-405B. The results highlight the promise of selective translation as a practical and effective method for improving multilingual alignment in LLMs. △ Less

Submitted 15 October, 2025; v1 submitted 18 July, 2025; originally announced July 2025.

Probing Hadron Scattering in Lattice Gauge Theories on Qudit Quantum Computers

Authors: Rohan Joshi, Jan C. Louw, Michael Meth, Jesse J. Osborne, Kevin Mato, Guo-Xian Su, Martin Ringbauer, Jad C. Halimeh

Abstract: An overarching goal in the flourishing field of quantum simulation for high-energy physics is the first-principles study of the microscopic dynamics of scattering processes on a quantum computer. Currently, this is hampered by small system sizes and a restriction to two-level representations of the gauge fields in state-of-the-art quantum simulators. Here, we propose efficient experimentally feasi… ▽ More An overarching goal in the flourishing field of quantum simulation for high-energy physics is the first-principles study of the microscopic dynamics of scattering processes on a quantum computer. Currently, this is hampered by small system sizes and a restriction to two-level representations of the gauge fields in state-of-the-art quantum simulators. Here, we propose efficient experimentally feasible digital qudit quantum circuits for far-from-equilibrium quench dynamics of a $\mathrm{U}(1)$ quantum link lattice gauge theory, where the electric and gauge fields are represented as spin-$1$ operators. Using dedicated numerical simulations, we probe scattering processes in this model on these proposed circuits, focusing on meson-meson and meson-antimeson collisions. The latter are not possible with a two-level representation of the fields, highlighting the suitability of qudits in exploring scattering processes relevant to quantum electrodynamics. The probed scattering dynamics showcases rich physics, including meson flipping and a reflection-transmission transition in meson-antimeson collisions as a function of the gauge coupling strength. Our simulations, which include realistic noise models of dephasing and depolarization, show very good agreement with the exact noiseless dynamics, signaling the readiness of current qudit platforms to observe microscopic scattering dynamics with significantly shallower circuit depths than their qubit counterparts. △ Less

Submitted 16 July, 2025; originally announced July 2025.

Comments: $21$ pages, $15$ figures