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Towards better nuclear charge radii
Authors:
István Angeli,
Dimiter L. Balabanski,
Paraskevi Dimitriou,
Dipti,
Kieran T. Flanagan,
Georgi Georgiev,
Mikhail Gorchtein,
Paul Gùeye,
Fabian Heiße,
Andreas Knecht,
Kei Minamisono,
Wilfried Nörtershäuser,
Ben Ohayon,
Natalia S. Oreshkina,
B. K. Sahoo,
Hunter Staiger,
Endre Takacs,
Xiaofei Yang,
Deyan T. Yordanov
Abstract:
Nuclear charge radii constitute a physical observable of growing significance across multiple subdisciplines of physics and related fields. Their determination relies on a combination of complementary experimental techniques and advanced theoretical frameworks. Current recommended values are informed by the outcomes of several independent working groups, each employing distinct methodological appr…
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Nuclear charge radii constitute a physical observable of growing significance across multiple subdisciplines of physics and related fields. Their determination relies on a combination of complementary experimental techniques and advanced theoretical frameworks. Current recommended values are informed by the outcomes of several independent working groups, each employing distinct methodological approaches and evaluation strategies. The present effort is directed toward a more precise and reliable extraction of charge radii, as well as the development of a modern, transparent, and methodologically robust compilation of recommended values.
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Submitted 10 April, 2026;
originally announced April 2026.
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Terahertz emission from interdigitated photoconductive antennas based on Ge-on-Si
Authors:
Dhanashree Chemate,
Abhishek Singh,
Ruturaj Puranik,
Utkarsh Pandey,
Dipti Gupta,
Siddhartha P. Duttagupta,
Shriganesh S. Prabhu
Abstract:
An interdigitated photoconductive antenna (i-PCA) for terahertz (THz) emission with a novel metal-insulator-semiconductor interface is designed with the aim of developing compact and scalable THz devices. The photoconductive material is an amorphous germanium (Ge) film deposited using DC magnetron sputtering. The antenna electrodes are composed of gold-germanium (AuGe). With the integration of a s…
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An interdigitated photoconductive antenna (i-PCA) for terahertz (THz) emission with a novel metal-insulator-semiconductor interface is designed with the aim of developing compact and scalable THz devices. The photoconductive material is an amorphous germanium (Ge) film deposited using DC magnetron sputtering. The antenna electrodes are composed of gold-germanium (AuGe). With the integration of a silicon dioxide (SiO2) layer that acts as an electrical mask on alternate active areas, we present a simple approach to fabricate a large-area i-PCA. Along with a simplified fabrication compared to other existing designs, our approach increases the electrical robustness of the emitter and reduces the inactive gap area on the device. The i-PCA is capable of THz emission up to 2.5 THz and 36 dB signal-to-noise ratio (SNR), and is promising for applications in CMOS technologies.
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Submitted 11 January, 2026; v1 submitted 3 December, 2025;
originally announced December 2025.
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Extreme Ultraviolet Spectroscopy of Highly Charged Lu and Yb Ions for Nuclear Charge Radius Determination
Authors:
Hunter Staiger,
Endre Takacs,
Steven A. Blundell,
Naoki Kimura,
Hiroyuki A. Sakaue,
Ronald F. Garcia Ruiz,
Witold Nazarewicz,
Paul-Gerhard Reinhard,
Chowdhury A. Faiyaz,
Chihiro Suzuki,
Dipti,
István Angeli,
Yuri Ralchenko,
Izumi Murakami,
Daiji Kato,
Yuki Nagai,
Ryuji Takaoka,
Yoshiki Miya,
Nobuyuki Nakamura
Abstract:
We report a high-precision determination of the natural-abundance-averaged nuclear charge-radius difference between Yb and Lu using extreme ultraviolet (EUV) spectroscopy of highly charged ions (HCIs). By measuring the $D_1$ transition energies in Na- and Mg-like charge states of Lu and Yb confined in the Tokyo electron-beam ion trap, we extract meV-level energy shifts that are directly sensitive…
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We report a high-precision determination of the natural-abundance-averaged nuclear charge-radius difference between Yb and Lu using extreme ultraviolet (EUV) spectroscopy of highly charged ions (HCIs). By measuring the $D_1$ transition energies in Na- and Mg-like charge states of Lu and Yb confined in the Tokyo electron-beam ion trap, we extract meV-level energy shifts that are directly sensitive to nuclear-size effects. Transition-energy differences obtained from these spectra are compared with state-of-the-art relativistic many-body perturbation theory, including a new treatment of Mg-like ions. We develop a generalized framework to propagate uncertainties arising from nuclear deformation and surface diffuseness and evaluate corresponding nuclear-sensitivity coefficients. Combining Na- and Mg-like results yields mutually consistent radius differences, demonstrating the robustness of both the experimental calibration and the theoretical predictions. To determine absolute isotopic radii, we perform a generalized least-squares optimization incorporating our HCI constraints together with optical-isotope-shift data and muonic-atom results. This analysis establishes that the $^{175}$Lu charge radius is smaller than that of $^{174}$Yb, restoring the expected odd-even staggering across the $N=94$ isotonic chain. Our recommended value, $R(^{175}\text{Lu}) = 5.291(11)$ fm, reduces the uncertainty of the Lu radius by a factor of three compared with the previous electron-scattering result and resolves a long-standing anomaly in rare-earth nuclear systematics. This work demonstrates that EUV spectroscopy of HCIs provides a powerful and broadly applicable method for precision nuclear-structure studies in heavy, deformed nuclei. The techniques developed here enable future investigations of isotonic and isoelectronic sequences, including radioactive nuclides and higher-$Z$ systems.
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Submitted 25 November, 2025;
originally announced November 2025.
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Puzzling Isotonic Odd-Even Staggering of Charge Radii in Deformed Rare Earth Nuclei
Authors:
Endre Takacs,
Hunter Staiger,
Steven A. Blundell,
Naoki Kimura,
Hiroyuki A. Sakaue,
Ronald F. Garcia Ruiz,
Witold Nazarewicz,
Paul-Gerhard Reinhard,
Chowdhury A. Faiyaz,
Chihiro Suzuki,
Dipti,
István Angeli,
Yuri Ralchenko,
Izumi Murakami,
Daiji Kato,
Yuki Nagai,
Ryuji Takaoka,
Yoshiki Miya,
Nobuyuki Nakamura
Abstract:
The nuclear charge radius is a fundamental observable that encodes key aspects of nuclear structure, deformation, and pairing. Isotonic (constant neutron number) systematics in the deformed rare-earth region have long suggested that odd-$Z$ nuclei are more compact than their even-$Z$ neighbors - except for Lu, whose recommended radius appeared anomalously large relative to Yb and Hf. We report a h…
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The nuclear charge radius is a fundamental observable that encodes key aspects of nuclear structure, deformation, and pairing. Isotonic (constant neutron number) systematics in the deformed rare-earth region have long suggested that odd-$Z$ nuclei are more compact than their even-$Z$ neighbors - except for Lu, whose recommended radius appeared anomalously large relative to Yb and Hf. We report a high-precision determination of the natural-abundance-averaged Lu-Yb charge-radius difference using extreme-ultraviolet spectroscopy of highly charged Na-like and Mg-like ions, supported by high-accuracy relativistic atomic-structure calculations - a recently introduced method with the unique ability to measure inter-element charge radius differences. Combined with muonic-atom and optical isotope-shift data, our result resolves the longstanding Lu inversion anomaly and reestablishes a pronounced odd-even staggering along the $N=94$ isotonic chain. The magnitude of this staggering is unexpectedly large, far exceeding that observed in semi-magic nuclei and in deformed isotopic sequences. State-of-the-art nuclear density functional theory calculations, including quantified uncertainties, fail to reproduce this enhancement, possibly indicating missing structural effects in current models. Our work demonstrates the power of highly charged ions for precise, element-crossing charge-radius measurements and provides stringent new constraints for future theoretical and experimental studies of nuclear-size systematics.
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Submitted 27 November, 2025; v1 submitted 24 November, 2025;
originally announced November 2025.
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Strong anharmonicity dictates ultralow thermal conductivities of type-I clathrates
Authors:
Dipti Jasrasaria,
Timothy C. Berkelbach
Abstract:
Type-I clathrate solids have attracted significant interest due to their ultralow thermal conductivities and subsequent promise for thermoelectric applications, yet the mechanisms underlying these properties are not well understood. Here, we extend the framework of vibrational dynamical mean-field theory (VDMFT) to calculate temperature-dependent thermal transport properties of $X_8$Ga$_{16}$Ge…
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Type-I clathrate solids have attracted significant interest due to their ultralow thermal conductivities and subsequent promise for thermoelectric applications, yet the mechanisms underlying these properties are not well understood. Here, we extend the framework of vibrational dynamical mean-field theory (VDMFT) to calculate temperature-dependent thermal transport properties of $X_8$Ga$_{16}$Ge$_{30}$, where $X=$ Ba, Sr, using a many-body Green's function approach. We find that nonresonant scattering between cage acoustic modes and rattling modes leads to a reduction of acoustic phonon lifetimes and thus thermal conductivities. Moreover, we find that the moderate temperature dependence of conductivities above 300 K, which is consistent with experimental measurements, cannot be reproduced by standard perturbation theory calculations, which predict a $T^{-1}$ dependence. Therefore, we conclude that nonperturbative anharmonic effects, including four- and higher-phonon scattering processes, are responsible for the ultralow thermal conductivities of type-I clathrates.
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Submitted 26 June, 2025; v1 submitted 12 September, 2024;
originally announced September 2024.
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Simulating anharmonic vibrational polaritons beyond the long wavelength approximation
Authors:
Dipti Jasrasaria,
Arkajit Mandal,
David R. Reichman,
Timothy C. Berkelbach
Abstract:
In this work we investigate anharmonic vibrational polaritons formed due to strong light-matter interactions in an optical cavity between radiation modes and anharmonic vibrations beyond the long-wavelength limit. We introduce a conceptually simple description of light-matter interactions, where spatially localized cavity radiation modes couple to localized vibrations. Within this theoretical fram…
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In this work we investigate anharmonic vibrational polaritons formed due to strong light-matter interactions in an optical cavity between radiation modes and anharmonic vibrations beyond the long-wavelength limit. We introduce a conceptually simple description of light-matter interactions, where spatially localized cavity radiation modes couple to localized vibrations. Within this theoretical framework, we employ self-consistent phonon theory and vibrational dynamical mean-field theory to efficiently simulate momentum-resolved vibrational-polariton spectra, including effects of anharmonicity. Numerical simulations in model systems demonstrate the accuracy and applicability of our approach.
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Submitted 12 September, 2024;
originally announced September 2024.
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Nonperturbative Simulation of Anharmonic Rattler Dynamics in Type-I Clathrates with Vibrational Dynamical Mean-Field Theory
Authors:
Dipti Jasrasaria,
Timothy C. Berkelbach
Abstract:
We use vibrational dynamical mean-field theory (VDMFT) to study the vibrational structure of type-I clathrate solids, specifically X$_8$Ga$_{16}$Ge$_{30}$, where X=Ba,Sr. These materials are cage-like chemical structures hosting loosely bound guest atoms, resulting in strong anharmonicity, short phonon lifetimes, and ultra-low thermal conductivities. Presenting the methodological developments nece…
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We use vibrational dynamical mean-field theory (VDMFT) to study the vibrational structure of type-I clathrate solids, specifically X$_8$Ga$_{16}$Ge$_{30}$, where X=Ba,Sr. These materials are cage-like chemical structures hosting loosely bound guest atoms, resulting in strong anharmonicity, short phonon lifetimes, and ultra-low thermal conductivities. Presenting the methodological developments necessary for this first application to three-dimensional, atomistic materials, we validate our approach through comparison to molecular dynamics simulations and show that VDMFT is extremely accurate at a fraction of the cost. Through the use of nonperturbative methods, we find that anharmonicity is dominated by four-phonon and higher-order scattering processes, and it causes rattler modes to shift up in frequency by 50% (10 cm$^{-1}$) and to have lifetimes of less than 1 ps; this behavior is not captured by traditional perturbation theory. Furthermore, we analyze the phonon self-energy and find that anharmonicity mixes guest rattling modes and cage acoustic modes, significantly changing the character of the harmonic phonons.
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Submitted 31 July, 2024; v1 submitted 12 February, 2024;
originally announced February 2024.
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Detecting, distinguishing, and spatiotemporally tracking photogenerated charge and heat at the nanoscale
Authors:
Hannah L. Weaver,
Cora M. Went,
Joeson Wong,
Dipti Jasrasaria,
Eran Rabani,
Harry A. Atwater,
Naomi S. Ginsberg
Abstract:
Since dissipative processes are ubiquitous in semiconductors, characterizing how electronic and thermal energy transduce and transport at the nanoscale is vital for understanding and leveraging their fundamental properties. For example, in low-dimensional transition metal dichalcogenides (TMDCs), excess heat generation upon photoexcitation is difficult to avoid since even with modest injected exci…
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Since dissipative processes are ubiquitous in semiconductors, characterizing how electronic and thermal energy transduce and transport at the nanoscale is vital for understanding and leveraging their fundamental properties. For example, in low-dimensional transition metal dichalcogenides (TMDCs), excess heat generation upon photoexcitation is difficult to avoid since even with modest injected exciton densities, exciton-exciton annihilation still occurs. Both heat and photoexcited electronic species imprint transient changes in the optical response of a semiconductor, yet the unique signatures of each are difficult to disentangle in typical spectra due to overlapping resonances. In response, we employ stroboscopic optical scattering microscopy (stroboSCAT) to simultaneously map both heat and exciton populations in few-layer \ch{MoS2} on relevant nanometer and picosecond length- and time scales and with 100-mK temperature sensitivity. We discern excitonic contributions to the signal from heat by combining observations close to and far from exciton resonances, characterizing photoinduced dynamics for each. Our approach is general and can be applied to any electronic material, including thermoelectrics, where heat and electronic observables spatially interplay, and lays the groundwork for direct and quantitative discernment of different types of coexisting energy without recourse to complex models or underlying assumptions.
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Submitted 5 August, 2023; v1 submitted 23 May, 2023;
originally announced May 2023.
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Accelerating exploration of Marine Cloud Brightening impacts on tipping points Using an AI Implementation of Fluctuation-Dissipation Theorem
Authors:
Haruki Hirasawa,
Sookyung Kim,
Peetak Mitra,
Subhashis Hazarika,
Salva Ruhling-Cachay,
Dipti Hingmire,
Kalai Ramea,
Hansi Singh,
Philip J. Rasch
Abstract:
Marine cloud brightening (MCB) is a proposed climate intervention technology to partially offset greenhouse gas warming and possibly avoid crossing climate tipping points. The impacts of MCB on regional climate are typically estimated using computationally expensive Earth System Model (ESM) simulations, preventing a thorough assessment of the large possibility space of potential MCB interventions.…
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Marine cloud brightening (MCB) is a proposed climate intervention technology to partially offset greenhouse gas warming and possibly avoid crossing climate tipping points. The impacts of MCB on regional climate are typically estimated using computationally expensive Earth System Model (ESM) simulations, preventing a thorough assessment of the large possibility space of potential MCB interventions. Here, we describe an AI model, named AiBEDO, that can be used to rapidly projects climate responses to forcings via a novel application of the Fluctuation-Dissipation Theorem (FDT). AiBEDO is a Multilayer Perceptron (MLP) model that uses maps monthly-mean radiation anomalies to surface climate anomalies at a range of time lags. By leveraging a large existing dataset of ESM simulations containing internal climate noise, we use AiBEDO to construct an FDT operator that successfully projects climate responses to MCB forcing, when evaluated against ESM simulations. We propose that AiBEDO-FDT can be used to optimize MCB forcing patterns to reduce tipping point risks while minimizing negative side effects in other parts of the climate.
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Submitted 3 February, 2023;
originally announced February 2023.
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Experimental investigation on the performance of thermosyphon charging of a single-medium stratified storage system for concentrated solar power applications
Authors:
Dipti Ranjan Parida,
Saptarshi Basu,
Dhanush A P
Abstract:
Concentrated solar power (CSP) plants utilize two-tank, sensible-heat thermal energy storage (TES) for uninterrupted electricity generation. However, the cost for the design and operation of TES is expensive. Therefore, researchers are focusing on implementing single-tank storage. Additional cutbacks can be made by utilizing pump-less thermosyphon charging for the TES. But prior thermosyphon resea…
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Concentrated solar power (CSP) plants utilize two-tank, sensible-heat thermal energy storage (TES) for uninterrupted electricity generation. However, the cost for the design and operation of TES is expensive. Therefore, researchers are focusing on implementing single-tank storage. Additional cutbacks can be made by utilizing pump-less thermosyphon charging for the TES. But prior thermosyphon researches for TES are related to domestic water-heating systems of small-capacity (<100 liters) and low-temperature (<100 °C). Thus, investigations into thermosyphon charging for high-temperature storage are desired. This study focuses on thermosyphon-charging and storing of a single-medium stratified TES. The experiments were conducted on a 370 liters cylindrical storage (aspect ratio 4:1) with a heat-pipe system (3-liter volume) acting as a collector. Dowtherm-A oil was used as the heat transfer fluid (HTF), and the thermal expansion of HTF was accommodated in an expansion tank via two different designs (top and bottom connections from storage tank to expansion tank). Moreover, continuous and pulsatile charging are investigated for low (150 °C) and high (250 and 300 °C) temperatures. The results indicate that the maximum HTF temperature coming out of the heating pipes is ~25 °C more for the bottom-expansion design. Furthermore, it results in higher charging efficiency than the top-expansion setup for high-temperature studies. Finally, it is revealed that under design conditions, there are limits on the degree of thermal stratification achieved in the charging cycle and the maximum layover time allowable for interrupted charging. These results provide insights into the operational strategy of thermosyphon-charging stratified storage for CSP applications.
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Submitted 30 November, 2022;
originally announced November 2022.
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Development of Ni doped SnO$_2$ Dilute magnetic oxides for electronics and spintronics applications
Authors:
Y. S. Worku,
V. V. Srinivasu,
Dipti R. Sahu
Abstract:
We used a solid-state reaction method to prepare Sn$_{1-x}$Ni$_x$O$_2$ with $x$ = 0, 0.05, 0.1, 0.15 polycrystalline compounds. A rutile phase with tetragonal crystal structure was confirmed by X-ray diffraction. At room temperature, the magnetisation study shows that the saturation magnetization increases with Ni doping content whereas the coercive field decreases after $x$=0.1. The spin number i…
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We used a solid-state reaction method to prepare Sn$_{1-x}$Ni$_x$O$_2$ with $x$ = 0, 0.05, 0.1, 0.15 polycrystalline compounds. A rutile phase with tetragonal crystal structure was confirmed by X-ray diffraction. At room temperature, the magnetisation study shows that the saturation magnetization increases with Ni doping content whereas the coercive field decreases after $x$=0.1. The spin number increases as the Ni doping concentration increases, indicating that the incorporation of Ni into the Sn sites increases the number of spins interacting to improve the ferromagnetic phase , which is like saturation magnetization and coercive field.
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Submitted 3 June, 2022;
originally announced June 2022.
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Bistable soliton switching dynamics in a $\mathcal{PT}$-symmetric coupler with saturable nonlinearity
Authors:
Ambaresh Sahoo,
Dipti Kanika Mahato,
A. Govindarajan,
Amarendra K. Sarma
Abstract:
We investigate the switching dynamics in a $\mathcal{PT}$-symmetric fiber coupler composed of a saturable nonlinear material as the core. In such a saturable nonlinear medium, bistable solitons may evolve due to the balance between dispersion and saturable nonlinearity, which we extend in the context of the $\mathcal{PT}$-symmetric coupler. Our investigations of power-controlled and phase-sensitiv…
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We investigate the switching dynamics in a $\mathcal{PT}$-symmetric fiber coupler composed of a saturable nonlinear material as the core. In such a saturable nonlinear medium, bistable solitons may evolve due to the balance between dispersion and saturable nonlinearity, which we extend in the context of the $\mathcal{PT}$-symmetric coupler. Our investigations of power-controlled and phase-sensitive switching show richer soliton switching dynamics than the currently existing conventional counterparts, which may lead to ultrafast and efficient all-optical switching dynamics at very low power owing to the combined effects of $\mathcal{PT}$ symmetry and saturable nonlinearity. In addition to the input power, the relative phase of the input solitons and saturable coefficient are additional controlling parameters that efficiently tailor the switching dynamics. Also, we provide a suitable range of system and pulse parameters that would be helpful for the practical realization of the coupler to use in all-optical switching devices and photonic circuits. Finally, we develop a variational approach to analytically investigate the switching dynamics in such $\mathcal{PT}$-symmetric couplers that excellently predicts the numerical findings.
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Submitted 3 October, 2022; v1 submitted 13 December, 2021;
originally announced December 2021.
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Switching dynamics of femtosecond solitons in parity-time-symmetric coupled optical waveguides
Authors:
Ambaresh Sahoo,
Dipti Kanika Mahato,
A. Govindarajan,
Amarendra K. Sarma
Abstract:
We report a detailed study on soliton steering dynamics in a parity-time-symmetric directional coupler in the femtosecond domain, which requires incorporation of higher-order perturbative effects such as third-order and fourth-order dispersions, self-steepening, and intrapulse Raman scattering. With a high gain/loss, the combination of all these effects is found to stabilize the soliton pulse evol…
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We report a detailed study on soliton steering dynamics in a parity-time-symmetric directional coupler in the femtosecond domain, which requires incorporation of higher-order perturbative effects such as third-order and fourth-order dispersions, self-steepening, and intrapulse Raman scattering. With a high gain/loss, the combination of all these effects is found to stabilize the soliton pulse evolution in the coupler from the chaotic behavior of unperturbed evolution. This work demonstrates that efficient soliton steering can be achieved at very low critical power and a relatively higher gain/loss even in the femtosecond regime.
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Submitted 1 October, 2022; v1 submitted 21 November, 2021;
originally announced November 2021.
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Dispersion Managed Generation of Peregrine Solitons and Kuznetsov-Ma Breather in an Optical Fiber
Authors:
Dipti Kanika Mahato,
A. Govindarajan,
M. Lakshmanan,
Amarendra K. Sarma
Abstract:
Optical rogue waves and its variants have been studied quite extensively in the context of optical fiber in recent years. It has been realized that dispersion management in optical fiber is experimentally much more feasible compared to its nonlinear counterpart. In this work, we report Kuznetsov-Ma (KM)-like breathers from the first three orders of rational solutions of the nonlinear Schrödinger e…
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Optical rogue waves and its variants have been studied quite extensively in the context of optical fiber in recent years. It has been realized that dispersion management in optical fiber is experimentally much more feasible compared to its nonlinear counterpart. In this work, we report Kuznetsov-Ma (KM)-like breathers from the first three orders of rational solutions of the nonlinear Schrödinger equation with periodic modulation of the dispersion coefficient along the fiber axis. The breather dynamics are then controlled by proper choice of modulating parameters. Additionally, the evolution of new one-peak and two-peak breather-like solutions has been displayed corresponding to the second-order rational solution. Direct numerical simulations based on modulational instability has also been executed which agree well with the analytical results, thereby making the proposed system more feasible for experimental realization.
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Submitted 29 December, 2020;
originally announced December 2020.
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Dielectronic resonances of LMn and LNn (n $\geq$ 4) series in highly-charged M-shell tungsten ions
Authors:
Dipti,
A. Borovik Jr.,
R. Silwal,
J. M. Dreiling,
A. C. Gall,
E. Takacs,
Yu. Ralchenko
Abstract:
We present spectroscopic measurements and detailed theoretical analysis of inner-shell LMn and LNn (n $\geq$ 4) dielectronic resonances in highly-charged M-shell ions of tungsten. The x-ray emission from W$^{49+}$ through W$^{64+}$ was recorded at the electron beam ion trap (EBIT) facility at the National Institute of Standards and Technology (NIST) with a high-purity Ge detector for electron beam…
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We present spectroscopic measurements and detailed theoretical analysis of inner-shell LMn and LNn (n $\geq$ 4) dielectronic resonances in highly-charged M-shell ions of tungsten. The x-ray emission from W$^{49+}$ through W$^{64+}$ was recorded at the electron beam ion trap (EBIT) facility at the National Institute of Standards and Technology (NIST) with a high-purity Ge detector for electron beam energies between 6.8 keV and 10.8 keV. The measured spectra clearly show the presence of strong resonance features as well as direct excitation spectral lines. The analysis of the recorded spectra with large-scale collisional-radiative (CR) modeling of the EBIT plasma allowed us to unambiguously identify numerous dielectronic resonances associated with excitations of the inner-shell 2s$_{1/2}$, 2p$_{1/2}$, and 2p$_{3/2}$ electrons.
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Submitted 4 March, 2020;
originally announced March 2020.
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Controllable Kuznetsov Ma-like breather generation via dispersion modulation in the nonlinear Schrödinger equation with variable coefficients
Authors:
Dipti Kanika Mahato,
Amarendra K. Sarma
Abstract:
The nonlinear Schrödinger equation with variable coefficients has applications in numerous areas of physics,specifically in the context of nonlinear optics and Bose-Einstein condensate. Apart from the usual bright and dark-soliton solutions, the so-called rational soliton solutions are perceived to have tremendous impact in futuristic applications and understanding many natural phenomena. In this…
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The nonlinear Schrödinger equation with variable coefficients has applications in numerous areas of physics,specifically in the context of nonlinear optics and Bose-Einstein condensate. Apart from the usual bright and dark-soliton solutions, the so-called rational soliton solutions are perceived to have tremendous impact in futuristic applications and understanding many natural phenomena. In this work, we have studied various orders of rational solution of the variable coefficient nonlinear Schrödinger equation. It is possible to extract the first and the second-order controlled KM-like breather by periodic modulation of the dispersion along the propagation direction. The amplitude of the dispersion modulation controls the background as well as the breather peak power in the case of the first-order rational soliton solution, whereas the spatial frequency controls the breathing frequency of the KM-like breather. Our study reveals that it is possible to obtain various new features in the third order rational soliton by modulating the dispersion parameter.
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Submitted 31 December, 2020; v1 submitted 30 September, 2019;
originally announced October 2019.
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Temperature Tunable Optical Transmission control of VO2 nanostructures by IR based 1-D Photonic crystals as hybrid Photonic absorbers
Authors:
Dipti Umed Singh,
Omkar Bhoite,
Remya Narayanan
Abstract:
Effect of 1-D photonic crystals on optical transmission of VO2 is studied by depositing thin films of VO2 nanoparticles on SiO2/TiO2 distributed Bragg reflectors (DBR) in the near infrared (IR) spectrum as per earlier theoretical predictions of J. Phys. D: Appl. Phys. 51 375102 (2018). Monoclinic VO2 nanoparticles with tuned crystallinity were synthesized by a facile solution processing method. Mo…
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Effect of 1-D photonic crystals on optical transmission of VO2 is studied by depositing thin films of VO2 nanoparticles on SiO2/TiO2 distributed Bragg reflectors (DBR) in the near infrared (IR) spectrum as per earlier theoretical predictions of J. Phys. D: Appl. Phys. 51 375102 (2018). Monoclinic VO2 nanoparticles with tuned crystallinity were synthesized by a facile solution processing method. Moderately crystalline (MC) and highly crystalline (HC) VO2 nanostructures were obtained by varying its synthesis temperature and post growth annealing conditions. Both MC VO2 and HC VO2 films exhibit expected reduction in optical transmission in the IR region due to its structural phase transition from monoclinic (insulator) to rutile (metallic) around critical temperature of 68 °C. By combining VO2 films on a 40% transmitting DBR structure, the average optical transmission further went down to ~ 20%. Number of stacks of DBR plays a key role in such effective reduction of optical transmission in IR. When the number of stacks of DBR is further increased from 4 to 7, optical transmission of metallic VO2 films on DBR nearly vanishes in NearIR spectrum in such vanadium dioxide/1D photonic crystal based composite photonic structures. Such temperature controlled, enhanced, broad band optical response can be a promising design for VO2 nanoparticle based hybrid photonic absorbers for various smart window applications.
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Submitted 25 October, 2019; v1 submitted 20 July, 2019;
originally announced August 2019.
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High Performance Fin-FET electrochemical sensor with high-k dielectric materials
Authors:
Serena Rollo,
Dipti Rani,
Wouter Olthuis,
César Pascual García
Abstract:
In this work we combine a Fin Field Effect Transistor (Fin-FET) characterised by a high height to width aspect ratio with high-k dielectric materials to study the optimized design for chemical-FETs to provide higher transconductance (and thus a better signal to noise ratio), increased dynamic range and chemical stability. We used pH sensing to verify the design. We explored the sensitivity and res…
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In this work we combine a Fin Field Effect Transistor (Fin-FET) characterised by a high height to width aspect ratio with high-k dielectric materials to study the optimized design for chemical-FETs to provide higher transconductance (and thus a better signal to noise ratio), increased dynamic range and chemical stability. We used pH sensing to verify the design. We explored the sensitivity and response linearity of silicon dioxide, alumina and hafnium oxide as dielectric materials sensing pH, and compared their chemical stability in different acids. The high aspect ratio fin geometry of the sensor provides high currents, as well as a planar conduction channel more reliable than traditional silicon nanowires. The hafnium oxide Fin-FET configuration performed the best delivering the most linear response both for the output and transfer characteristics providing a wider dynamic range. Hafnium oxide also showed the best chemical stability. Thus, we believe that the developed high aspect ratio Fin-FETs/high-k dielectric system can offer the best compromise of performance of FET-based sensors.
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Submitted 25 July, 2019;
originally announced July 2019.
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A high aspect ratio Fin-Ion Sensitive Field Effect Transistor: compromises towards better electrochemical bio-sensing
Authors:
Serena Rollo,
Dipti Rani,
Renaud Leturcq,
Wouter Olthuis,
César Pascual García
Abstract:
The development of next generation medicines demand more sensitive and reliable label free sensing able to cope with increasing needs of multiplexing and shorter times to results. Field effect transistor-based biosensors emerge as one of the main possible technologies to cover the existing gap. The general trend for the sensors has been miniaturisation with the expectation of improving sensitivity…
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The development of next generation medicines demand more sensitive and reliable label free sensing able to cope with increasing needs of multiplexing and shorter times to results. Field effect transistor-based biosensors emerge as one of the main possible technologies to cover the existing gap. The general trend for the sensors has been miniaturisation with the expectation of improving sensitivity and response time, but presenting issues with reproducibility and noise level. Here we propose a Fin-Field Effect Transistor (FinFET) with a high heigth to width aspect ratio for electrochemical biosensing solving the issue of nanosensors in terms of reproducibility and noise, while keeping the fast response time. We fabricated different devices and characterised their performance with their response to the pH changes that fitted to a Nernst-Poisson model. The experimental data were compared with simulations of devices with different aspect ratio, stablishing an advantage in total signal and linearity for the FinFETs with higher aspect ratio. In addition, these FinFETs promise the optimisation of reliability and efficiency in terms of limits of detection, for which the interplay of the size and geometry of the sensor with the diffusion of the analytes plays a pivotal role.
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Submitted 8 January, 2019;
originally announced January 2019.
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Measuring the Variation in Nuclear Charge Radius of Xe Isotopes by EUV Spectroscopy of Highly-Charged Na-like Ions
Authors:
R. Silwal,
A. Lapierre,
J. D. Gillaspy,
J. M. Dreiling,
S. A. Blundell,
Dipti,
A. Borovik Jr,
G. Gwinner,
A. C. C. Villari,
Yu. Ralchenko,
E. Takacs
Abstract:
The variation in mean-square nuclear charge radius of xenon isotopes was measured utilizing a new method based on extreme ultraviolet spectroscopy of highly charged Na-like ions. The isotope shift of the Na-like D1 (3s $^{2}$S$_{1/2}$ - 3p $^2$P$_{1/2}$) transition between the $^{124}$Xe and $^{136}$Xe isotopes was experimentally determined using the electron beam ion trap facility at the National…
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The variation in mean-square nuclear charge radius of xenon isotopes was measured utilizing a new method based on extreme ultraviolet spectroscopy of highly charged Na-like ions. The isotope shift of the Na-like D1 (3s $^{2}$S$_{1/2}$ - 3p $^2$P$_{1/2}$) transition between the $^{124}$Xe and $^{136}$Xe isotopes was experimentally determined using the electron beam ion trap facility at the National Institute of Standards and Technology. The mass shift and the field shift coefficients were calculated with enhanced precision by relativistic many-body perturbation theory and multi-configuration Dirac-Hartree-Fock method. The mean-square nuclear charge radius difference was found to be $δ<r^2>^{136, 124}$ = 0.269(0.042) fm$^2$. Our result has smaller uncertainty than previous experimental results and agrees with the recommended value by Angeli and Marinova [I. Angeli and K. P. Marinova, At. Data and Nucl. Data Tables {\bf 99}, 69-95 (2013)].
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Submitted 17 September, 2018; v1 submitted 22 June, 2018;
originally announced June 2018.
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Space-Filling Curves as a Novel Crystal Structure Representation for Machine Learning Models
Authors:
Dipti Jasrasaria,
Edward O. Pyzer-Knapp,
Dmitrij Rappoport,
Alan Aspuru-Guzik
Abstract:
A fundamental problem in applying machine learning techniques for chemical problems is to find suitable representations for molecular and crystal structures. While the structure representations based on atom connectivities are prevalent for molecules, two-dimensional descriptors are not suitable for describing molecular crystals. In this work, we introduce the SFC-M family of feature representatio…
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A fundamental problem in applying machine learning techniques for chemical problems is to find suitable representations for molecular and crystal structures. While the structure representations based on atom connectivities are prevalent for molecules, two-dimensional descriptors are not suitable for describing molecular crystals. In this work, we introduce the SFC-M family of feature representations, which are based on Morton space-filling curves, as an alternative means of representing crystal structures. Latent Semantic Indexing (LSI) was employed in a novel setting to reduce sparsity of feature representations. The quality of the SFC-M representations were assessed by using them in combination with artificial neural networks to predict Density Functional Theory (DFT) single point, Ewald summed, lattice, and many-body dispersion energies of 839 organic molecular crystal unit cells from the Cambridge Structural Database that consist of the elements C, H, N, and O. Promising initial results suggest that the SFC-M representations merit further exploration to improve its ability to predict solid-state properties of organic crystal structures
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Submitted 19 August, 2016;
originally announced August 2016.
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Quantum Information through Angular momentum of Photon
Authors:
Dipti Banerjee,
Dipan Sinha
Abstract:
The angular momentum of photons is the key source of quantum information. The transfer angular momentum is possible as circularly polarized light passed through wave plates. The twisted birefringent medium behaves as Q-plate. The passage of circularly polarized light through two consecutive half wave plates traces a closed curve on Poincare sphere. As a result the geometric phase in association wi…
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The angular momentum of photons is the key source of quantum information. The transfer angular momentum is possible as circularly polarized light passed through wave plates. The twisted birefringent medium behaves as Q-plate. The passage of circularly polarized light through two consecutive half wave plates traces a closed curve on Poincare sphere. As a result the geometric phase in association with gain of orbital angular momentum is developed.
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Submitted 14 July, 2014; v1 submitted 21 June, 2014;
originally announced June 2014.
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Quantifying phases in homogenous twisted birefringent medium
Authors:
Dipti Banerjee,
Srutarshi Banerjee
Abstract:
The internal birefringence of an optical medium develops the dynamical phase through natural rotation of incident polarized light. The uniform twist of the medium induces an external birefringence in the system.This can be visualized through the geometric phase by the solid angle in association with the angular twist per unit thickness of the medium $k$.An equivalent physical analysis in the…
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The internal birefringence of an optical medium develops the dynamical phase through natural rotation of incident polarized light. The uniform twist of the medium induces an external birefringence in the system.This can be visualized through the geometric phase by the solid angle in association with the angular twist per unit thickness of the medium $k$.An equivalent physical analysis in the $l=1$ orbital angular momentum sphere also has been pointed out.
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Submitted 3 March, 2013; v1 submitted 11 February, 2013;
originally announced February 2013.
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The spinorial representation of polarized light and Berry phase
Authors:
Dipti Banerjee
Abstract:
From relativistic point of view it has been shown here that a polarized photon can be visualized to give an equivalent spinorial description when the two-component spinor is the eigenvector of $2\times2$ Hermitian, Polarization matrix. The Berry phase of the initial state can be calculated by matrix method as it complete one rotation over a closed path on the Poincare's sphere.
From relativistic point of view it has been shown here that a polarized photon can be visualized to give an equivalent spinorial description when the two-component spinor is the eigenvector of $2\times2$ Hermitian, Polarization matrix. The Berry phase of the initial state can be calculated by matrix method as it complete one rotation over a closed path on the Poincare's sphere.
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Submitted 10 July, 2011;
originally announced July 2011.
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The study of birefringent homogenous medium with geometric phase
Authors:
Dipti Banerjee
Abstract:
The property of linear and circular birefringence at each point of the optical medium has been evaluated here from differential matrix $N$ using the Jones calculus.This matrix lies on the OAM sphere for $l=1$ orbital angular momentum.The geometric phase is developed by twisting the medium uniformly about the direction of propagation of the light ray. The circular birefringence of the medium,is vis…
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The property of linear and circular birefringence at each point of the optical medium has been evaluated here from differential matrix $N$ using the Jones calculus.This matrix lies on the OAM sphere for $l=1$ orbital angular momentum.The geometric phase is developed by twisting the medium uniformly about the direction of propagation of the light ray. The circular birefringence of the medium,is visualized through the solid angle and the angular twist per unit thickness of the medium, $k$,that is equivalent to the topological charge of the optical element.
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Submitted 15 March, 2011;
originally announced March 2011.
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The Study of Geometric Phase in Twisted Crystal
Authors:
Dipti Banerjee
Abstract:
The polarization matrix ($2\times2$) obtained from two component eigen-spinors of spherical harmonics help us to evaluate the differential matrix $N$ of the anisotropic optical medium. The geometric phase is realized through {\it helicity} of photon, assuming the transmission of polarized light through the crystal which has been twisted about the normal to its surface over a closed path.
The polarization matrix ($2\times2$) obtained from two component eigen-spinors of spherical harmonics help us to evaluate the differential matrix $N$ of the anisotropic optical medium. The geometric phase is realized through {\it helicity} of photon, assuming the transmission of polarized light through the crystal which has been twisted about the normal to its surface over a closed path.
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Submitted 16 August, 2004;
originally announced August 2004.
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Geometric Phase From Dielectric Matrix
Authors:
Dipti Banerjee
Abstract:
The dielectric property $(2\times2)$ of the anisotropic optical medium is found out considering the polarized photon as two component spinor of spherical harmonics.The Geometric Phase of single polarized photon has been evaluated in two ways. The phase two-form of the dielectric matrix through a twist and the Pancharatnam phase (GP) through the change of angular momentum of the incident polarize…
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The dielectric property $(2\times2)$ of the anisotropic optical medium is found out considering the polarized photon as two component spinor of spherical harmonics.The Geometric Phase of single polarized photon has been evaluated in two ways. The phase two-form of the dielectric matrix through a twist and the Pancharatnam phase (GP) through the change of angular momentum of the incident polarized photon over a closed triangular path on the extended Poincare sphere. The helicity in connection with the spin angular momentum of the chiral photon plays the key role in developing these phase holonomies.
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Submitted 29 July, 2004;
originally announced July 2004.