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Simulation of topological superconductors and their competing orders using photon-mediated interactions
Authors:
Anjun Chu,
Joyce Kwan,
Eric Yilun Song,
Seth Hew Peng Chew,
James K. Thompson,
Ana Maria Rey
Abstract:
Realizing and controlling the unconventional pairing featured by topological superconductors remains a central challenge. We introduce a cavity QED quantum simulator that engineers competing chiral $p_x+ip_y$ and $d_{x^2-y^2}+id_{xy}$ orders by tailoring cavity-mediated couplings between atomic pseudospins that emulate momentum-dependent pairing channels. The desired spatially inhomogeneous cavity…
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Realizing and controlling the unconventional pairing featured by topological superconductors remains a central challenge. We introduce a cavity QED quantum simulator that engineers competing chiral $p_x+ip_y$ and $d_{x^2-y^2}+id_{xy}$ orders by tailoring cavity-mediated couplings between atomic pseudospins that emulate momentum-dependent pairing channels. The desired spatially inhomogeneous cavity-mediated couplings can be engineered in a 2D optical lattice using incommensurate cavity-lattice wavelengths naturally occurring in cavity QED systems. This minimal and fully tunable platform enables controlled state preparation and continuous measurement of superconducting order parameters, revealing phases in both equilibrium and sudden-quench settings with a single dominant pairing channel, as well as coexistence regimes with competing pairing channels. Crucially, our implementation allows direct observation of topological transitions in and out of equilibrium, providing a powerful route to the quantum simulation of competing topological superconducting phases that remain elusive in solid-state and ultracold-atom systems.
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Submitted 19 December, 2025;
originally announced December 2025.
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Reconfigurable dissipative entanglement between many spin ensembles: from robust quantum sensing to many-body state engineering
Authors:
Anjun Chu,
Mikhail Mamaev,
Martin Koppenhöfer,
Ming Yuan,
Aashish A. Clerk
Abstract:
An attractive approach for stabilizing entangled many-body spin states is to employ engineered dissipation. Most existing proposals either target relatively simple collective spin states, or require numerous independent and complex dissipative processes. Here, we show a surprisingly versatile scheme for many-body reservoir engineering that relies solely on fully collective single-excitation decay,…
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An attractive approach for stabilizing entangled many-body spin states is to employ engineered dissipation. Most existing proposals either target relatively simple collective spin states, or require numerous independent and complex dissipative processes. Here, we show a surprisingly versatile scheme for many-body reservoir engineering that relies solely on fully collective single-excitation decay, augmented with local Hamiltonian terms. Crucially, all these ingredients are readily available in cavity QED setups. Our method is based on splitting the spin system into groups of sub-ensembles, and provides an easily tunable setup for stabilizing a broad family of pure, highly entangled states with closed-form analytic descriptions. Our results have immediate application to multi-ensemble quantum metrology, enabling Heisenberg-limited sensing of field gradients and curvatures. Notably, our approach solves an important challenge in differential quantum sensing by providing the first example of Heisenberg-limited differential sensing immune to common-mode noise and accessible with only simple one-body measurements. The same setup also allows the stabilization of an entire family of entangled states in a 1D chain of spin ensembles with symmetry-protected topological (SPT) order, and have a direct connection to the outputs of sequential unitary circuits. A special case of our protocol efficiently stabilizes the celebrated Affleck-Kennedy-Lieb-Tasaki (AKLT) state.
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Submitted 11 March, 2026; v1 submitted 8 October, 2025;
originally announced October 2025.
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Probing the Critical Point (CritPt) of AI Reasoning: a Frontier Physics Research Benchmark
Authors:
Minhui Zhu,
Minyang Tian,
Xiaocheng Yang,
Tianci Zhou,
Lifan Yuan,
Penghao Zhu,
Eli Chertkov,
Shengyan Liu,
Yufeng Du,
Ziming Ji,
Indranil Das,
Qingzhi Chen,
Junyi Cao,
Yufeng Du,
Jiabin Yu,
Peixue Wu,
Jinchen He,
Yifan Su,
Yikun Jiang,
Yujie Zhang,
Chang Liu,
Ze-Min Huang,
Weizhen Jia,
Yunkai Wang,
Farshid Jafarpour
, et al. (40 additional authors not shown)
Abstract:
While large language models (LLMs) with reasoning capabilities are progressing rapidly on high-school math competitions and coding, can they reason effectively through complex, open-ended challenges found in frontier physics research? And crucially, what kinds of reasoning tasks do physicists want LLMs to assist with? To address these questions, we present the CritPt (Complex Research using Integr…
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While large language models (LLMs) with reasoning capabilities are progressing rapidly on high-school math competitions and coding, can they reason effectively through complex, open-ended challenges found in frontier physics research? And crucially, what kinds of reasoning tasks do physicists want LLMs to assist with? To address these questions, we present the CritPt (Complex Research using Integrated Thinking - Physics Test, pronounced "critical point"), the first benchmark designed to test LLMs on unpublished, research-level reasoning tasks that broadly covers modern physics research areas, including condensed matter, quantum physics, atomic, molecular & optical physics, astrophysics, high energy physics, mathematical physics, statistical physics, nuclear physics, nonlinear dynamics, fluid dynamics and biophysics. CritPt consists of 71 composite research challenges designed to simulate full-scale research projects at the entry level, which are also decomposed to 190 simpler checkpoint tasks for more fine-grained insights. All problems are newly created by 50+ active physics researchers based on their own research. Every problem is hand-curated to admit a guess-resistant and machine-verifiable answer and is evaluated by an automated grading pipeline heavily customized for advanced physics-specific output formats. We find that while current state-of-the-art LLMs show early promise on isolated checkpoints, they remain far from being able to reliably solve full research-scale challenges: the best average accuracy among base models is only 5.7%, achieved by GPT-5 (high), moderately rising to around 10% when equipped with coding tools. Through the realistic yet standardized evaluation offered by CritPt, we highlight a large disconnect between current model capabilities and realistic physics research demands, offering a foundation to guide the development of scientifically grounded AI tools.
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Submitted 8 May, 2026; v1 submitted 30 September, 2025;
originally announced September 2025.
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Time-resolved pairing gap spectroscopy in a quantum simulator of fermionic superfluidity inside an optical cavity
Authors:
Dylan J. Young,
Eric Yilun Song,
Anjun Chu,
Diego Barberena,
Zhijing Niu,
Vera M. Schäfer,
Robert J. Lewis-Swan,
Ana Maria Rey,
James K. Thompson
Abstract:
We use an ensemble of laser-cooled strontium atoms in a high-finesse cavity to cleanly emulate the technique of rf spectroscopy employed in studies of BEC-BCS physics in fermionic superfluids of degenerate cold gases. Here, we leverage the multilevel internal structure of the atoms to study the physics of Cooper pair breaking in this system. In doing so, we observe and distinguish the properties o…
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We use an ensemble of laser-cooled strontium atoms in a high-finesse cavity to cleanly emulate the technique of rf spectroscopy employed in studies of BEC-BCS physics in fermionic superfluids of degenerate cold gases. Here, we leverage the multilevel internal structure of the atoms to study the physics of Cooper pair breaking in this system. In doing so, we observe and distinguish the properties of two distinct many-body gaps, the BCS pairing gap and the spectral gap, using nondestructive readout techniques. The latter is found to depend on the populations of the internal atomic states, reflecting the chemical potential dependence predicted in fermionic superfluids. This work opens the path for more fully exploiting the rich internal structure of atoms in cavity QED emulators to study both analogous systems and also more exotic states yet to be realized.
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Submitted 22 August, 2024;
originally announced August 2024.
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A dissipation-induced superradiant transition in a strontium cavity-QED system
Authors:
Eric Yilun Song,
Diego Barberena,
Dylan J. Young,
Edwin Chaparro,
Anjun Chu,
Sanaa Agarwal,
Zhijing Niu,
Jeremy T. Young,
Ana Maria Rey,
James K. Thompson
Abstract:
In cavity quantum electrodynamics (QED), emitters and a resonator are coupled together to enable precise studies of quantum light-matter interactions. Over the past few decades, this has led to a variety of quantum technologies such as more precise inertial sensors, clocks, memories, controllable qubits, and quantum simulators. Furthermore, the intrinsically dissipative nature of cavity QED platfo…
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In cavity quantum electrodynamics (QED), emitters and a resonator are coupled together to enable precise studies of quantum light-matter interactions. Over the past few decades, this has led to a variety of quantum technologies such as more precise inertial sensors, clocks, memories, controllable qubits, and quantum simulators. Furthermore, the intrinsically dissipative nature of cavity QED platforms makes them a natural testbed for exploring driven-dissipative phenomena in open quantum systems as well as equilibrium and non-equilibrium phase transitions in quantum optics. One such model, the so-called cooperative resonance fluorescence (CRF) model, concerns the behavior of coherently driven emitters in the presence of collective dissipation (superradiance). Despite tremendous interest, this model has yet to be realized in a clean experimental system. Here we provide an observation of the continuous superradiant phase transition predicted in the CRF model using an ensemble of ultracold $^{88}$Sr atoms coupled to a driven high-finesse optical cavity on a long-lived optical transition. Below a critical drive, atoms quickly reach a steady state determined by the self-balancing of the drive and the collective dissipation. The steady state possesses a macroscopic dipole moment and corresponds to a superradiant phase. Above a critical drive strength, the atoms undergo persistent Rabi-like oscillations until other decoherence processes kick in. In fact, our platform also allows us to witness the change of this phase transition from second to first order induced by single-particle spontaneous emission, which pushes the system towards a different steady state. Our observations are a first step towards finer control of driven-dissipative systems, which have been predicted to generate quantum states that can be harnessed for quantum information processing and in particular quantum sensing.
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Submitted 26 August, 2024; v1 submitted 20 August, 2024;
originally announced August 2024.
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Exploring the dynamical interplay between mass-energy equivalence, interactions and entanglement in an optical lattice clock
Authors:
Anjun Chu,
Victor J. Martínez-Lahuerta,
Maya Miklos,
Kyungtae Kim,
Peter Zoller,
Klemens Hammerer,
Jun Ye,
Ana Maria Rey
Abstract:
We propose protocols that probe manifestations of the mass-energy equivalence in an optical lattice clock (OLC) interrogated with spin coherent and entangled quantum states. To tune and uniquely distinguish the mass-energy equivalence effects (gravitational redshift and second order Doppler shift) in such a setting, we devise a dressing protocol using an additional nuclear spin state. We then anal…
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We propose protocols that probe manifestations of the mass-energy equivalence in an optical lattice clock (OLC) interrogated with spin coherent and entangled quantum states. To tune and uniquely distinguish the mass-energy equivalence effects (gravitational redshift and second order Doppler shift) in such a setting, we devise a dressing protocol using an additional nuclear spin state. We then analyze the dynamical interplay between photon-mediated interactions and gravitational redshift and show that such interplay can lead to entanglement generation and frequency synchronization dynamics. In the regime where all atomic spins synchronize, we show the synchronization time depends on the initial entanglement of the state and can be used as a proxy of its metrological gain compared to a classical state. Our work opens new possibilities for exploring the effects of general relativity on quantum coherence and entanglement in OLC experiments.
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Submitted 3 March, 2025; v1 submitted 6 June, 2024;
originally announced June 2024.
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Coherent evolution of superexchange interaction in seconds long optical clock spectroscopy
Authors:
William R. Milner,
Stefan Lannig,
Mikhail Mamaev,
Lingfeng Yan,
Anjun Chu,
Ben Lewis,
Max N. Frankel,
Ross B. Hutson,
Ana Maria Rey,
Jun Ye
Abstract:
Measurement science now connects strongly with engineering of quantum coherence, many-body states, and entanglement. To scale up the performance of an atomic clock using a degenerate Fermi gas loaded in a three-dimensional optical lattice, we must understand complex many-body Hamiltonians to ensure meaningful gains for metrological applications. In this work, we use a near unity filled Sr 3D latti…
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Measurement science now connects strongly with engineering of quantum coherence, many-body states, and entanglement. To scale up the performance of an atomic clock using a degenerate Fermi gas loaded in a three-dimensional optical lattice, we must understand complex many-body Hamiltonians to ensure meaningful gains for metrological applications. In this work, we use a near unity filled Sr 3D lattice to study the effect of a tunable Fermi-Hubbard Hamiltonian. The clock laser introduces a spin-orbit coupling spiral phase and breaks the isotropy of superexchange interactions, changing the Heisenberg spin model into one exhibiting XXZ-type spin anisotropy. By tuning the lattice confinement and applying imaging spectroscopy we map out favorable atomic coherence regimes. With weak transverse confinement, both s- and p-wave interactions contribute to decoherence and atom loss, and their contributions can be balanced. At deep transverse confinement, we directly observe coherent superexchange interactions, tunable via on-site interaction and site-to-site energy shift, on the clock Ramsey fringe contrast over timescales of multiple seconds. This study provides a groundwork for using a 3D optical lattice clock to probe quantum magnetism and spin entanglement
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Submitted 20 February, 2024;
originally announced February 2024.
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Observing dynamical phases of BCS superconductors in a cavity QED simulator
Authors:
Dylan J. Young,
Anjun Chu,
Eric Yilun Song,
Diego Barberena,
David Wellnitz,
Zhijing Niu,
Vera M. Schäfer,
Robert J. Lewis-Swan,
Ana Maria Rey,
James K. Thompson
Abstract:
In conventional Bardeen-Cooper-Schrieffer (BCS) superconductors, electrons with opposite momenta bind into Cooper pairs due to an attractive interaction mediated by phonons in the material. While superconductivity naturally emerges at thermal equilibrium, it can also emerge out of equilibrium when the system's parameters are abruptly changed. The resulting out-of-equilibrium phases are predicted t…
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In conventional Bardeen-Cooper-Schrieffer (BCS) superconductors, electrons with opposite momenta bind into Cooper pairs due to an attractive interaction mediated by phonons in the material. While superconductivity naturally emerges at thermal equilibrium, it can also emerge out of equilibrium when the system's parameters are abruptly changed. The resulting out-of-equilibrium phases are predicted to occur in real materials and ultracold fermionic atoms but have not yet all been directly observed. Here we realize an alternate way to generate the proposed dynamical phases using cavity quantum electrodynamics (cavity QED). Our system encodes the presence or absence of a Cooper pair in a long-lived electronic transition in $^{88}$Sr atoms coupled to an optical cavity and represents interactions between electrons as photon-mediated interactions through the cavity. To fully explore the phase diagram, we manipulate the ratio between the single-particle dispersion and the interactions after a quench and perform real-time tracking of subsequent dynamics of the superconducting order parameter using non-destructive measurements. We observe regimes where the order parameter decays to zero (phase I), assumes a non-equilibrium steady-state value (phase II), or exhibits persistent oscillations (phase III). This opens up exciting prospects for quantum simulation, including the potential to engineer unconventional superconductors and to probe beyond mean-field effects like the spectral form factor, and for increasing coherence time for quantum sensing.
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Submitted 23 February, 2024; v1 submitted 31 May, 2023;
originally announced June 2023.
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Control and amplification of Bloch oscillations via photon-mediated interactions
Authors:
Haoqing Zhang,
Anjun Chu,
Chengyi Luo,
James K. Thompson,
Ana Maria Rey
Abstract:
We propose a scheme to control and enhance atomic Bloch oscillations via photon-mediated interactions in an optical lattice supported by a standing-wave cavity with incommensurate lattice and cavity wavelengths. Our scheme uses position-dependent atom-light couplings in an optical cavity to spatially prepare an array of atoms at targeted lattice sites starting from a thermal gas. On this initial s…
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We propose a scheme to control and enhance atomic Bloch oscillations via photon-mediated interactions in an optical lattice supported by a standing-wave cavity with incommensurate lattice and cavity wavelengths. Our scheme uses position-dependent atom-light couplings in an optical cavity to spatially prepare an array of atoms at targeted lattice sites starting from a thermal gas. On this initial state we take advantage of dispersive position-dependent atom-cavity couplings to perform non-destructive measurements of single-particle Bloch oscillations, and to generate long-range interactions self-tuned by atomic motion. The latter leads to the generation of dynamical phase transitions in the deep lattice regime and the amplification of Bloch oscillations in the shallow lattice regime. Our work introduces new possibilities accessible in state-of-the-art cavity QED experiments for the exploration of many-body dynamics in self-tunable potentials.
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Submitted 13 February, 2024; v1 submitted 19 January, 2023;
originally announced January 2023.
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Photon-mediated correlated hopping in a synthetic ladder
Authors:
Anjun Chu,
Asier Piñeiro Orioli,
Diego Barberena,
James K. Thompson,
Ana Maria Rey
Abstract:
We propose a new direction in quantum simulation that uses multilevel atoms in an optical cavity as a toolbox to engineer new types of bosonic models featuring correlated hopping processes in a synthetic ladder spanned by atomic ground states. The underlying mechanisms responsible for correlated hopping are collective cavity-mediated interactions that dress a manifold of excited levels in the far…
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We propose a new direction in quantum simulation that uses multilevel atoms in an optical cavity as a toolbox to engineer new types of bosonic models featuring correlated hopping processes in a synthetic ladder spanned by atomic ground states. The underlying mechanisms responsible for correlated hopping are collective cavity-mediated interactions that dress a manifold of excited levels in the far detuned limit. By weakly coupling the ground state levels to these dressed states using two laser drives with appropriate detunings, one can engineer correlated hopping processes while suppressing undesired single-particle and collective shifts of the ground state levels. We discuss the rich many-body dynamics that can be realized in the synthetic ladder including pair production processes, chiral transport and light-cone correlation spreading. The latter illustrates that an effective notion of locality can be engineered in a system with fully collective interactions.
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Submitted 3 August, 2022;
originally announced August 2022.
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Bosonic pair production and squeezing for optical phase measurements in long-lived dipoles coupled to a cavity
Authors:
Bhuvanesh Sundar,
Diego Barberena,
Asier Piñeiro Orioli,
Anjun Chu,
James K. Thompson,
Ana Maria Rey,
Robert J. Lewis-Swan
Abstract:
We propose to simulate bosonic pair creation using large arrays of long-lived dipoles with multilevel internal structure coupled to an undriven optical cavity. Entanglement between the atoms, generated by the exchange of virtual photons through a common cavity mode, grows exponentially fast and is described by two-mode squeezing of effective bosonic quadratures. The mapping between an effective bo…
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We propose to simulate bosonic pair creation using large arrays of long-lived dipoles with multilevel internal structure coupled to an undriven optical cavity. Entanglement between the atoms, generated by the exchange of virtual photons through a common cavity mode, grows exponentially fast and is described by two-mode squeezing of effective bosonic quadratures. The mapping between an effective bosonic model and the natural spin description of the dipoles allows us to realize the analog of optical homodyne measurements via straightforward global rotations and population measurements of the electronic states, and we propose to exploit this for quantum-enhanced sensing of an optical phase (common and differential between two ensembles). We discuss a specific implementation based on Sr atoms and show that our sensing protocol is robust to sources of decoherence intrinsic to cavity platforms. Our proposal can open unique opportunities for next-generation optical atomic clocks.
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Submitted 16 March, 2023; v1 submitted 27 April, 2022;
originally announced April 2022.
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Hamiltonian engineering of spin-orbit coupled fermions in a Wannier-Stark optical lattice clock
Authors:
Alexander Aeppli,
Anjun Chu,
Tobias Bothwell,
Colin J. Kennedy,
Dhruv Kedar,
Peiru He,
Ana Maria Rey,
Jun Ye
Abstract:
Engineering a Hamiltonian system with tunable interactions provides opportunities to optimize performance for quantum sensing and explore emerging phenomena of many-body systems. An optical lattice clock based on partially delocalized Wannier-Stark states in a gravity-tilted shallow lattice supports superior quantum coherence and adjustable interactions via spin-orbit coupling, thus presenting a p…
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Engineering a Hamiltonian system with tunable interactions provides opportunities to optimize performance for quantum sensing and explore emerging phenomena of many-body systems. An optical lattice clock based on partially delocalized Wannier-Stark states in a gravity-tilted shallow lattice supports superior quantum coherence and adjustable interactions via spin-orbit coupling, thus presenting a powerful spin model realization. The relative strength of the on-site and off-site interactions can be tuned to achieve a zero density shift at a `magic' lattice depth. This mechanism, together with a large number of atoms, enables the demonstration of the most stable atomic clock while minimizing a key systematic uncertainty related to atomic density. Interactions can also be maximized by driving off-site Wannier-Stark transitions, realizing a ferromagnetic to paramagnetic dynamical phase transition.
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Submitted 15 January, 2022;
originally announced January 2022.
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Hybrid Magneto Photonic Material Structure for Plasmon Assisted Magnetic Switching
Authors:
Alan Hwader Chu,
Bradlee Beauchamp,
Deesha Shah,
Aveek Dutta,
Alexandra Boltasseva,
Vladimir M. Shalaev,
Ernesto E. Marinero
Abstract:
We have proposed the use of surface plasmon resonances at the interface of hybrid magneto-photonic heterostructures [Opt. Mat. Exp., 7, 4316 (2017)] for all-optical control of the macroscopic spin orientation in nanostructures in fs time scales. This requires strong spin-photon coupling for the resonant enhancement of opto-magnetic fields, generated through the inverse Faraday effect, in magnetic…
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We have proposed the use of surface plasmon resonances at the interface of hybrid magneto-photonic heterostructures [Opt. Mat. Exp., 7, 4316 (2017)] for all-optical control of the macroscopic spin orientation in nanostructures in fs time scales. This requires strong spin-photon coupling for the resonant enhancement of opto-magnetic fields, generated through the inverse Faraday effect, in magnetic nanostructures with perpendicular anisotropy. Here we report on the development of nm thick interlayers to control the growth orientation of hcp-Co alloys grown on refractory plasmonic materials to align the magnetic axis out-of-plane, thereby meeting key requirements for the realization of ultrafast magneto-photonic devices.
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Submitted 11 September, 2020; v1 submitted 16 June, 2020;
originally announced June 2020.
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Efficient ground-state cooling of large trapped-ion chains with an EIT tripod scheme
Authors:
L. Feng,
W. L. Tan,
A. De,
A. Menon,
A. Chu,
G. Pagano,
C. Monroe
Abstract:
We report the electromagnetically-induced-transparency (EIT) cooling of a large trapped $^{171}$Yb$^+$ ion chain to the quantum ground state. Unlike conventional EIT cooling, we engage a four-level tripod structure and achieve fast sub-Doppler cooling over all motional modes. We observe simultaneous ground-state cooling across the complete transverse mode spectrum of up to $40$ ions, occupying a b…
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We report the electromagnetically-induced-transparency (EIT) cooling of a large trapped $^{171}$Yb$^+$ ion chain to the quantum ground state. Unlike conventional EIT cooling, we engage a four-level tripod structure and achieve fast sub-Doppler cooling over all motional modes. We observe simultaneous ground-state cooling across the complete transverse mode spectrum of up to $40$ ions, occupying a bandwidth of over $3$ MHz. The cooling time is observed to be less than $300\,μ$s, independent of the number of ions. Such efficient cooling across the entire spectrum is essential for high-fidelity quantum operations using trapped ion crystals for quantum simulators or quantum computers.
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Submitted 27 April, 2020; v1 submitted 10 April, 2020;
originally announced April 2020.
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Simulation of XXZ Spin Models using Sideband Transitions in Trapped Bosonic Gases
Authors:
Anjun Chu,
Johannes Will,
Jan Arlt,
Carsten Klempt,
Ana Maria Rey
Abstract:
We theoretically propose and experimentally demonstrate the use of motional sidebands in a trapped ensemble of $^{87}$Rb atoms to engineer tunable long-range XXZ spin models. We benchmark our simulator by probing a ferromagnetic to paramagnetic dynamical phase transition in the Lipkin-Meshkov-Glick (LMG) model, a collective XXZ model plus additional transverse and longitudinal fields, via Rabi spe…
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We theoretically propose and experimentally demonstrate the use of motional sidebands in a trapped ensemble of $^{87}$Rb atoms to engineer tunable long-range XXZ spin models. We benchmark our simulator by probing a ferromagnetic to paramagnetic dynamical phase transition in the Lipkin-Meshkov-Glick (LMG) model, a collective XXZ model plus additional transverse and longitudinal fields, via Rabi spectroscopy. We experimentally reconstruct the boundary between the dynamical phases, which is in good agreement with mean-field theoretical predictions. Our work introduces new possibilities in quantum simulation of anisotropic spin-spin interactions and quantum metrology enhanced by many-body entanglement.
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Submitted 28 October, 2020; v1 submitted 2 April, 2020;
originally announced April 2020.
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Infrared narrow band gap nanocrystals: recent progresses relative to imaging and active detection
Authors:
Charlie Greboval,
Simon Ferre,
Vincent Noguier,
Audrey Chu,
Junling Qu,
Sang-Soo Chee,
Gregory Vincent,
Emmanuel Lhuillier
Abstract:
Current technologies for infrared detection have been based on epitaxially grown semiconductors. Here we review some of the recent developments relative to colloidal nanocrystals and their use as building blocks for the design of low-cost infrared sensors. We focus on HgTe nanocrystals which appear as the only material leading to infrared photoconductivity and ultra-broad spectral tunability: from…
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Current technologies for infrared detection have been based on epitaxially grown semiconductors. Here we review some of the recent developments relative to colloidal nanocrystals and their use as building blocks for the design of low-cost infrared sensors. We focus on HgTe nanocrystals which appear as the only material leading to infrared photoconductivity and ultra-broad spectral tunability: from the visible to the long-wave infrared. We review some of the important results which demonstrated that colloidal nanocrystals can be compatible with air stable operations, fast detection, and strong absorption. We discuss the recent progresses relative to multipixel devices and show results obtained by coupling short-wave infrared nanoparticles with CMOS circuits to achieve video rate VGA format imaging. In particular we present that nanocrystals are a promising material for long range (>150 m) active detection in both continuous wave and pulsed mode with a time resolution down to 10 ns.
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Submitted 30 January, 2020;
originally announced January 2020.
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Comments on "Pathway from Condensation via Fragmentation to Fermionization of Cold Bosonic Systems"
Authors:
A. Kwang-Hua Chu
Abstract:
We make remarks on the paper by Alon and Cederbaum [{\it Phys. Rev. Lett.} {\bf 95} 140402 (2005)]. The information about the Pauli blocking for Fermi-Dirac and Bose-Einstein particle statistics were presented.
We make remarks on the paper by Alon and Cederbaum [{\it Phys. Rev. Lett.} {\bf 95} 140402 (2005)]. The information about the Pauli blocking for Fermi-Dirac and Bose-Einstein particle statistics were presented.
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Submitted 3 October, 2005;
originally announced October 2005.
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Possible Pressure Effect for Superconductors
Authors:
A. Kwang-Hua Chu
Abstract:
We make an estimate of the possible range of $ΔT_c$ induced by high-pressure effects in post-metallic superconductors by using the theory of {\it extended irreversible/reversible thermodynamics} and Pippard's length scale. The relationship between the increment of the superconducting temperature and the increase of the pressure is parabolic.
We make an estimate of the possible range of $ΔT_c$ induced by high-pressure effects in post-metallic superconductors by using the theory of {\it extended irreversible/reversible thermodynamics} and Pippard's length scale. The relationship between the increment of the superconducting temperature and the increase of the pressure is parabolic.
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Submitted 29 August, 2005; v1 submitted 18 December, 2004;
originally announced December 2004.
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Possible Quantum Critical Region tuned by the Disorder and Pauli-Blocking Effects
Authors:
A. Kwang-Hua Chu
Abstract:
Based on the acoustic analog, we investigate both of the effects : disorder and (Pauli-blocking) interaction to the possible localization in electron gases by using the quantum discrete kinetic model. Effects of the disorder (or free-orientation : $θ$ which is related to the relative direction of scattering of particles w.r.t. to the normal of the propagating plane-wave front) which is introduce…
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Based on the acoustic analog, we investigate both of the effects : disorder and (Pauli-blocking) interaction to the possible localization in electron gases by using the quantum discrete kinetic model. Effects of the disorder (or free-orientation : $θ$ which is related to the relative direction of scattering of particles w.r.t. to the normal of the propagating plane-wave front) which is introduced into the Ühling-Uhlenbeck equations together with those of the Pauli-blocking are presented. We obtain the possible phase diagram (related to the strength of disorders and the mean free path) which resembles qualitatively that proposed by Abrahams$^{1}$.
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Submitted 25 November, 2004;
originally announced November 2004.
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Dispersion Relations for Waves propagating in Composite Fermion Gases
Authors:
A. Kwang-Hua Chu
Abstract:
The discrete Uehling-Uhlenbeck equations are solved to study the propagation of plane (sound) waves in a system of composite fermionic particles with hard-sphere interactions and the filling factor ($ν$) being 1/2. The Uehling-Uhlenbeck collision sum, as it is highly nonlinear, is linearized firstly and then decomposed by using the plane wave assumption. We compare the dispersion relations thus…
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The discrete Uehling-Uhlenbeck equations are solved to study the propagation of plane (sound) waves in a system of composite fermionic particles with hard-sphere interactions and the filling factor ($ν$) being 1/2. The Uehling-Uhlenbeck collision sum, as it is highly nonlinear, is linearized firstly and then decomposed by using the plane wave assumption. We compare the dispersion relations thus obtained by the relevant Pauli-blocking parameter $B$ which describes the different-statistics particles for the quantum analog of the discrete Boltzmann system when $B$ is positive (Bose gases), zero (Boltzmann gases), and negative (Fermi Gases). We found, as the effective magnetic field being zero ($ν$=1/2 using the composite fermion formulation), the electric and fluctuating (induced) magnetic fields effect will induce anomalous dispersion relations.
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Submitted 2 April, 2005; v1 submitted 22 November, 2004;
originally announced November 2004.