Showing 1–50 of 114 results for author: Zheng, L

Broadband phonon-velocity suppression and a finite anisotropic crossover in twisted bilayer SnSe

Authors: Peng Kang, Wei Yin, Da Wan, Shulin Bai, Sirui Fan, Qi Zou, Hongfeng Li, Xiao Xiang, Zhen Li, Yu Liu, Lei Zheng, Li-Dong Zhao

Abstract: Moiré superlattices reshape lattice dynamics without altering chemical composition, yet how crystal anisotropy modifies this control remains unclear. We combine density-functional-theory (DFT)-calibrated lattice-dynamical calculations with angle-matched untwisted controls to study puckered bilayer SnSe across seven commensurate twist angles ($3.18^\circ$--$8.77^\circ$). At 300 K, twisting suppress… ▽ More Moiré superlattices reshape lattice dynamics without altering chemical composition, yet how crystal anisotropy modifies this control remains unclear. We combine density-functional-theory (DFT)-calibrated lattice-dynamical calculations with angle-matched untwisted controls to study puckered bilayer SnSe across seven commensurate twist angles ($3.18^\circ$--$8.77^\circ$). At 300 K, twisting suppresses the band-path heat-capacity-weighted mean-square group velocity to 2.6--8.4\% of the control values; the suppression spans a broad frequency range rather than a few soft branches. The velocity response crosses over between $4.78^\circ$ and $3.82^\circ$ into a regime where the relaxed stacking textures and frequency-resolved velocity profiles become self-similar, with the normalized mean-square velocity ratio spanning only 11.1\% of its mean across the three smallest angles---a finite anisotropic crossover, not a singular-angle condition. Direct DFT--MACE force-constant agreement ($r=0.996$), uniform $4\times4\times1$ stability scans, and acoustic-sum-rule and path-density tests support the trend. The equilibrium trend is defined by six structures after excluding one relaxation-sensitive case. These results extend phonon twistronics to low-symmetry layered materials and identify crystal anisotropy as a key determinant of finite-angle phonon crossover behavior. △ Less

Submitted 15 August, 2026; originally announced August 2026.

Comments: 15 pages, 8 figures

200 mm Wafer-Scale Monolithic 3D Integration of Atomic Layer-Deposited Oxide Semiconductors

Authors: Chang Niu, Linjia Long, Luqi Zheng, Shuting Du, Jian-Yu Lin, Kisoo Nam, Zehao Lin, Chang Liu, Juanjuan Lu, Haiyan Wang, Haitong Li, Peide D. Ye

Abstract: Monolithic 3D (M3D) integration offers a pathway to overcome the scaling limits of conventional silicon complementary metal-oxide-semiconductor (CMOS) technology by extending dense vertical stacking of multifunctional logic and memory devices. Here, we demonstrate wafer-scale M3D integration of three tiers of atomic-layer-deposited (ALD) indium oxide (InOx)-based devices (>100,000 fabricated), inc… ▽ More Monolithic 3D (M3D) integration offers a pathway to overcome the scaling limits of conventional silicon complementary metal-oxide-semiconductor (CMOS) technology by extending dense vertical stacking of multifunctional logic and memory devices. Here, we demonstrate wafer-scale M3D integration of three tiers of atomic-layer-deposited (ALD) indium oxide (InOx)-based devices (>100,000 fabricated), including ferroelectric, enhancement-mode, and depletion-mode field-effect transistors, on 200 mm silicon wafers. We achieve threshold voltage standard deviation as low as 0.04 V, average electron mobility up to 91.6 cm2V-1s-1, and fully functional cross-tier circuits. A four-tier 3D computing-in-memory (CIM) accelerator targeting large language model workloads is developed using a custom InOx process design kit, delivering 1.4x to 2.9x speedup and comparable energy-delay product improvements over 2D baselines. These results establish ALD InOx M3D integration as a scalable and CMOS-compatible platform for next-generation artificial intelligence hardware and advanced electronics. △ Less

Submitted 10 August, 2026; originally announced August 2026.

Rotating mirror with all-directional pinch compressions - The beauty and simplicity in controlled nuclear fusion

Authors: Linjin Zheng

Abstract: Controlling nuclear fusion is so challenging that for decades, people have been asking: Are we closer to infinite clean energy? Upon the philosophy of beauty and simplicity, the current work points out that there can be a shortcut: the rotating mirror with detached electrodes and all-directional pinch compressions. This is based on the provisional patents filed recently by the University of Texas… ▽ More Controlling nuclear fusion is so challenging that for decades, people have been asking: Are we closer to infinite clean energy? Upon the philosophy of beauty and simplicity, the current work points out that there can be a shortcut: the rotating mirror with detached electrodes and all-directional pinch compressions. This is based on the provisional patents filed recently by the University of Texas at Austin. The device combines the steady-state and fast processes in the two main streams of controlled nuclear fusion research: magnetic confinement fusion and inertial confinement fusion. The fuel plasma is preheated in a steady-state process in a rotating mirror with detached electrodes and then the pinch compressions in both radial and longitudinal directions are applied as the fast process. Preheating and longitudinal compression, in addition to the radial compression, significantly boost the nuclear fusion rate. Fast compression after the preheating limits the time for thermalization between ions and electrons and, therefore, minimizes the impact of electron bremsstrahlung radiation loss on ions. Based on the existing experimental results, the current method can be extrapolated to have the potential to reach or exceed the Lawson criterion for the first demonstration of the feasibility of peaceful usage of nuclear fusion energy. △ Less

Submitted 29 July, 2026; originally announced July 2026.

Patagium and tail morphology shape aerodynamic performance and control authority in gliding-mammal-inspired wings

Authors: Liming Zheng, Baihui Chen, Alexander van Zuijlen, Salua Hamaza

Abstract: Gliding mammals exhibit diverse patagium and tail/uropatagium morphologies that may influence aerodynamic performance and maneuverability. Here, we use computational fluid dynamics to isolate the aerodynamic effects of representative gliding-mammal-inspired morphologies under controlled flow conditions. Three patagium configurations were compared to evaluate the effects of membrane outline on lift… ▽ More Gliding mammals exhibit diverse patagium and tail/uropatagium morphologies that may influence aerodynamic performance and maneuverability. Here, we use computational fluid dynamics to isolate the aerodynamic effects of representative gliding-mammal-inspired morphologies under controlled flow conditions. Three patagium configurations were compared to evaluate the effects of membrane outline on lift generation, drag, stall behavior and pitching moment. Three tail/uropatagium configurations were further tested under baseline, symmetric-deflection and asymmetric-deflection conditions to assess their longitudinal and lateral control authority. The results show that a broader patagium configuration generated the highest lift and lift coefficient, whereas an intermediate patagium morphology showed a smoother post-stall response with lower drag. For the tail configurations, the colugo-like integrated uropatagium enhanced lift and pitch-control authority under symmetric deflection, while the flat-tail configuration produced stronger rolling and yawing responses under asymmetric deflection. These findings indicate that gliding-mammal-inspired morphologies produce distinct aerodynamic trade-offs rather than a single optimal design. The results provide insight into the functional diversity of gliding mammal morphology and offer design guidance for bioinspired morphing aerial robots. △ Less

Submitted 2 July, 2026; originally announced July 2026.

Comments: 13 pages, 6 figures

Calibration and Performance of Germanium High Voltage Detectors for SuperCDMS SNOLAB

Authors: M. F. Albakry, I. Alkhatib, D. Alonso-González, J. Anczarski, T. Aralis, T. Aramaki, A. Ashtari Esfahani, I. Ataee Langroudy, R. Bhattacharyya, A. J. Biffl, P. L. Brink, M. Buchanan, R. Bunker, B. Cabrera, R. Calkins, R. A. Cameron, P. Camus, C. Cartaro, D. G. Cerdeño, Y. -Y. Chang, M. Chaudhuri, J. -H. Chen, R. Chen, J. Cooley, J. Corbett , et al. (118 additional authors not shown)

Abstract: As SuperCDMS SNOLAB is getting ready to search for low mass dark matter particles, using cryogenic Ge and Si detectors, a set of six of the new SuperCDMS High Voltage (HV) detectors (four Ge and two Si) were tested in the Cryogenic Underground TEst facility (CUTE) at SNOLAB. This provided the first opportunity to gain experience with this new detector type and assess their performance thoroughly u… ▽ More As SuperCDMS SNOLAB is getting ready to search for low mass dark matter particles, using cryogenic Ge and Si detectors, a set of six of the new SuperCDMS High Voltage (HV) detectors (four Ge and two Si) were tested in the Cryogenic Underground TEst facility (CUTE) at SNOLAB. This provided the first opportunity to gain experience with this new detector type and assess their performance thoroughly under low background conditions. Here we describe the SuperCDMS HV detector concept and discuss some of the newly developed analysis methods and approaches. Focusing on the Ge detectors, we investigate the detector performance under voltage bias (up to 90 V), exercise the low energy (keV to sub-keV range) calibration based on the electron capture peaks generated by the decay of $^{71}$Ge, assess the detector resolution, and demonstrate the unexpected (and encouraging) ability of these detectors to also measure high energy interactions in the hundreds of keV range with good resolution (better than 3% at 356 keV). △ Less

Submitted 24 June, 2026; originally announced June 2026.

Comments: 16 pages, 12 figures, submitted to Astroparticle Physics Journal

Ultralow shot noise limited giant passive resonant gyroscope for Earth rotation measurement

Authors: Yuhong Zhong, Yangsheng Cai, Zhanhao Liu, Lei Zheng, Yunhe Wang, Xiaojun Huang, Zhiyuan Wang, Kui Liu, Liangcheng Tu, Jun Luo, Zehuang Lu, Jie Zhang

Abstract: Optical gyroscopes directly measure the Earth's rotation and are promising instruments for real-time geophysical observations and Earth orientation parameter (EOP) determination requiring both high precision and high temporal resolution. Large-scale ring laser gyroscopes (RLGs) currently reach rotational resolutions around $10^{-11}\,\mathrm{(rad/s)/\sqrt{Hz}}$, but their quantum noise limits make… ▽ More Optical gyroscopes directly measure the Earth's rotation and are promising instruments for real-time geophysical observations and Earth orientation parameter (EOP) determination requiring both high precision and high temporal resolution. Large-scale ring laser gyroscopes (RLGs) currently reach rotational resolutions around $10^{-11}\,\mathrm{(rad/s)/\sqrt{Hz}}$, but their quantum noise limits make it challenging to meet the requirements of future high-temporal-resolution EOP measurements. Passive resonant gyroscopes (PRGs), on the other hand, offer a potentially lower photon shot noise limit and more flexible power scaling, even if their demonstrated rotational resolutions are still about two orders of magnitude below those of leading RLGs. Here we demonstrate a $64\,\mathrm{m^{2}}$ giant passive resonant gyroscope HUST-2, and develop with an extremely low shot noise level. We experimentally obtain a shot noise limited of $5.7(1)\times10^{-13}\,\mathrm{(rad/s)/\sqrt{Hz}}$ at $1\,\mathrm{mW}$ incident optical power, following the characteristic $1/\sqrt{P}$ scaling. Through systematic suppression of dominant technical noise sources, HUST-2 further achieves a measured rotational resolution of $3\times10^{-11}\,\mathrm{(rad/s)/\sqrt{Hz}}$, bringing PRGs into the performance regime of leading large-scale RLGs for the first time. The gap between the present demonstrated rotational resolution and the shot noise limit indicates nearly two orders of magnitude further improvement potential. Reaching this limit would enable high-precision length-of-day (LOD) measurements with $10$-$100\,\mathrm{s}$ temporal resolution and lays the foundation for future large-scale gyroscope networks dedicated to real-time EOP determination. △ Less

Submitted 11 June, 2026; v1 submitted 4 June, 2026; originally announced June 2026.

Comments: 9 pages, 5 figures

Sustaining high-fidelity quantum logic in neutral-atom circuits via mid-circuit operations

Authors: Rui Lin, You Li, Le-Tian Zheng, Tai-Ran Hu, Si-Yuan Chen, Hong-Ming Wu, Yu-Chen Zhang, Hao-Wen Cheng, Yu-Hao Deng, Zhan Wu, Ming-Cheng Chen, Jun Rui, Chao-Yang Lu, Jian-Wei Pan

Abstract: The realization of fault-tolerant quantum computation hinges on the ability to execute deep quantum circuits while maintaining gate fidelities consistently above error-correction thresholds. Although neutral-atom arrays have recently demonstrated high-fidelity two-qubit gates and early-stage logical quantum processors, sustaining such high performance across deep, repetitive circuits remains a for… ▽ More The realization of fault-tolerant quantum computation hinges on the ability to execute deep quantum circuits while maintaining gate fidelities consistently above error-correction thresholds. Although neutral-atom arrays have recently demonstrated high-fidelity two-qubit gates and early-stage logical quantum processors, sustaining such high performance across deep, repetitive circuits remains a formidable challenge due to cumulative motional heating and atom loss. Here we demonstrate a sustainable neutral-atom framework that overcomes these limitations by integrating a suite of hardware-efficient mid-circuit operations. We report a two-qubit controlled logic gate with a raw fidelity of 99.60(1)%, which is further increased to a fidelity of 99.81(1)% via non-destructive erasure detection. Crucially, by implementing in-circuit Raman sideband cooling and qubit re-initialization, we demonstrate that gate fidelities can be maintained at the ~99.8% level across multiple operational rounds without observable degradation. By actively managing the internal and motional entropy of the system mid-stream, our in-situ refreshable architecture provides a critical pathway for executing the repeated syndrome-extraction cycles required for large-scale, continuous quantum error correction. △ Less

Submitted 2 March, 2026; originally announced March 2026.

Photonic spiking reinforcement learning for intelligent routing

Authors: Shuiying Xiang, Yonghang Chen, Ling Zheng, Zhicong Tu, Xintao Zeng, Mengting Yu, Shuai Wang, Yahui Zhang, Xingxing Guo, Weitao Pan, Yue Hao

Abstract: Intelligent routing plays a key role in modern communication infrastructure, including data centers, computing networks, and future 6G networks. Although reinforcement learning (RL) has shown great potential for intelligent routing, its practical deployment remains constrained by high energy consumption and decision latency. Here, we propose a photonic spiking RL architecture that implements a pro… ▽ More Intelligent routing plays a key role in modern communication infrastructure, including data centers, computing networks, and future 6G networks. Although reinforcement learning (RL) has shown great potential for intelligent routing, its practical deployment remains constrained by high energy consumption and decision latency. Here, we propose a photonic spiking RL architecture that implements a proximal policy optimization (PPO)-based intelligent routing algorithm. The performance of the proposed approach is systematically evaluated on a software-defined network (SDN) with a fat-tree topology. The results demonstrate that, under various baseline traffic rate conditions, the PPO-based routing strategy significantly outperforms the conventional Dijkstra algorithm in several key performance metrics. Furthermore, a hardware-software collaborative framework of the spiking Actor network is realized for three typical baseline traffic rates, utilizing a photonic synapse chip based on a Mach-Zehnder interferometer (MZI) array and a photonic spiking neuron chip based on distributed feedback lasers with a saturable absorber (DFB-SAs). Experimental validation on 640 state-action pairs shows that the inference accuracy of the hardware-software collaborative framework is consistent with that of the pure algorithmic implementation. The impacts of different hidden-layer scales in the spiking Actor network and varying network size of fat-tree topology are further analyzed. The integration of photonic spiking RL with SDN-based routing establishes a novel paradigm for intelligent routing optimization, featuring ultra-low latency and high energy efficiency. This approach exhibits broad application prospects in real-time network optimization scenarios, including large-scale data centers, computing networks, satellite Internet systems, and future 6G networks. △ Less

Submitted 1 February, 2026; originally announced February 2026.

Comments: 22 pages, 7 figures, submitted to Opto-Electronic Science (under review)

Who will import hydrogen in 2050? Global assessment with China and US case studies

Authors: Veronika Brooks, Joshua Fragoso García, Lin Zheng, Viktor Paul Müller, Christoph Nolden, Dominik Möst, Martin Wietschel

Abstract: This study assesses the global hydrogen import potential in 2050 by looking at the renewable hydrogen production potential in prospective import-oriented countries. Renewable energy potentials calculated with a GIS based model and 2050 primary energy consumption projections are used to identify candidate importers by comparing it with expected demand. Two approaches are applied: (1) a meta-analysi… ▽ More This study assesses the global hydrogen import potential in 2050 by looking at the renewable hydrogen production potential in prospective import-oriented countries. Renewable energy potentials calculated with a GIS based model and 2050 primary energy consumption projections are used to identify candidate importers by comparing it with expected demand. Two approaches are applied: (1) a meta-analysis of literature on hydrogen production potential and demand for the identified countries, and (2) detailed regional analyses for the United States and China. The results suggest limited prospects for a fully global hydrogen market, although certain countries, such as Germany, Italy, and the Netherlands, are likely to remain net importers. By contrast, many Asian countries have enough renewable resources to decarbonise their energy systems. China and the United States may follow divergent pathways: while the United States is well placed to meet its overall demand, using its own resources, it can still benefit from regional connections with neighbouring countries. China is facing strong demand in its eastern regions, so it may source cost-effective renewable hydrogen from foreign countries instead of relying solely on domestic production. Overall, the findings suggest that hydrogen trade will likely remain regionally concentrated, shaped by the interplay of renewable resource distribution, energy demand, other available hydrogen production pathways, and infrastructure constraints. △ Less

Submitted 28 November, 2025; originally announced November 2025.

Comments: 42 pages, 9 figures, 4 tables

Search for low-mass electron-recoil dark matter using a single-charge sensitive SuperCDMS-HVeV Detector

Authors: SuperCDMS Collaboration, M. F. Albakry, I. Alkhatib, D. Alonso-González, J. Anczarski, T. Aralis, T. Aramaki, I. Ataee Langroudy, C. Bathurst, R. Bhattacharyya, A. J. Biffl, P. L. Brink, M. Buchanan, R. Bunker, B. Cabrera, R. Calkins, R. A. Cameron, C. Cartaro, D. G. Cerdeño, Y. -Y. Chang, M. Chaudhuri, J. -H. Chen, R. Chen, N. Chott, J. Cooley , et al. (124 additional authors not shown)

Abstract: We present constraints on low-mass dark matter electron scattering and absorption interactions using a SuperCDMS high-voltage eV-resolution (HVeV) detector. Data were taken underground in the NEXUS facility located at Fermilab with an overburden of 225 meters of water equivalent. The experiment benefits from the minimizing of luminescence from the printed circuit boards in the detector holder used… ▽ More We present constraints on low-mass dark matter electron scattering and absorption interactions using a SuperCDMS high-voltage eV-resolution (HVeV) detector. Data were taken underground in the NEXUS facility located at Fermilab with an overburden of 225 meters of water equivalent. The experiment benefits from the minimizing of luminescence from the printed circuit boards in the detector holder used in all previous HVeV studies. A blind analysis of $6.1\,\mathrm{g\cdot days}$ of exposure produces exclusion limits for dark matter-electron scattering cross sections for masses as low as $1\,\mathrm{MeV}/c^2$, as well as on the photon-dark photon mixing parameter and the coupling constant between axionlike particles and electrons for particles with masses $>1.2\,\mathrm{eV}/c^2$ probed via absorption processes. △ Less

Submitted 15 March, 2026; v1 submitted 3 September, 2025; originally announced September 2025.

Comments: 9 pages, 3 figures and 1 table

Journal ref: Phys. Rev. D 113, 032001 (2026)

Effects of reversed magnetic shear on the plasma rotation stabilization of resistive wall modes in tokamaks

Authors: Sui Wan, Ping Zhu, Linjin Zheng

Abstract: Effects of reversed magnetic shear on the plasma rotation stabilization of resistive wall modes in tokamaks are investigated using the AEGIS code. MHD equilibria in toroidal configuration from circular cross-sections to realistic CFETR-like scenarios with various magnetic shear profiles are considered. Two critical aspects of the $n=1$ RWM are examined: the influence of toroidal rotation on the un… ▽ More Effects of reversed magnetic shear on the plasma rotation stabilization of resistive wall modes in tokamaks are investigated using the AEGIS code. MHD equilibria in toroidal configuration from circular cross-sections to realistic CFETR-like scenarios with various magnetic shear profiles are considered. Two critical aspects of the $n=1$ RWM are examined: the influence of toroidal rotation on the unstable regime and the toroidal rotation frequency thresholds required for complete stabilization. It is found that strongly reversed magnetic shear consistently broadens the unstable $β_{\rm N}$ window in both circular and CFETR equilibria when toroidal rotation is included. Furthermore, reversed magnetic shear significantly reduces the rotational stabilization, resulting in narrower stability windows and notably higher toroidal rotation frequency thresholds required for complete RWM suppression compared to the cases with positive shear only. These results clearly demonstrate that the reversed magnetic shear in the advanced tokamak configuration imposes more stringent requirement for the effective toroidal rotation stabilization of the $n=1$ RWM. △ Less

Submitted 1 September, 2025; originally announced September 2025.

Multi-channel, multi-template event reconstruction for SuperCDMS data using machine learning

Authors: M. F. Albakry, I. Alkhatib, D. Alonso-Gonzalez, J. Anczarski, T. Aralis, T. Aramaki, I. Ataee Langroudy, C. Bathurst, R. Bhattacharyya, A. J. Biff, P. L. Brink, M. Buchanan, R. Bunker, B. Cabrera, R. Calkins, R. A. Cameron, C. Cartaro, D. G. Cerdeno, Y. -Y. Chang, M. Chaudhuri, J. H. Chen, R. Chen, N. Chott, J. Cooley, H. Coombes , et al. (117 additional authors not shown)

Abstract: SuperCDMS SNOLAB uses kilogram-scale germanium and silicon detectors to search for dark matter. Each detector has Transition Edge Sensors (TESs) patterned on the top and bottom faces of a large crystal substrate, with the TESs electrically grouped into six phonon readout channels per face. Noise correlations are expected among a detector's readout channels, in part because the channels and their r… ▽ More SuperCDMS SNOLAB uses kilogram-scale germanium and silicon detectors to search for dark matter. Each detector has Transition Edge Sensors (TESs) patterned on the top and bottom faces of a large crystal substrate, with the TESs electrically grouped into six phonon readout channels per face. Noise correlations are expected among a detector's readout channels, in part because the channels and their readout electronics are located in close proximity to one another. Moreover, owing to the large size of the detectors, energy deposits can produce vastly different phonon propagation patterns depending on their location in the substrate, resulting in a strong position dependence in the readout-channel pulse shapes. Both of these effects can degrade the energy resolution and consequently diminish the dark matter search sensitivity of the experiment if not accounted for properly. We present a new algorithm for pulse reconstruction, mathematically formulated to take into account correlated noise and pulse shape variations. This new algorithm fits N readout channels with a superposition of M pulse templates simultaneously - hence termed the N$\times$M filter. We describe a method to derive the pulse templates using principal component analysis (PCA) and to extract energy and position information using a gradient boosted decision tree (GBDT). We show that these new N$\times$M and GBDT analysis tools can reduce the impact from correlated noise sources while improving the reconstructed energy resolution for simulated mono-energetic events by more than a factor of three and for the 71Ge K-shell electron-capture peak recoils measured in a previous version of SuperCDMS called CDMSlite to $<$ 50 eV from the previously published value of $\sim$100 eV. These results lay the groundwork for position reconstruction in SuperCDMS with the N$\times$M outputs. △ Less

Submitted 27 August, 2025; originally announced August 2025.

Comments: 22 pages, 8 figures

Sub-5-fs compression and synchronization of relativistic electron bunches enabled by a high-gradient $α$-magnet and low-jitter photoinjector

Authors: Yining Yang, Zhiyuan Wang, Peng Lv, Baiting Song, Pengwei Huang, Yanqing Jia, Zhuoxuan Liu, Lianmin Zheng, Wenhui Huang, Pietro Musumeci, Chuanxiang Tang, Renkai Li

Abstract: Generating high-brightness relativistic electron bunches with few-femtosecond duration, while simultaneously achieving few-fs synchronization with ultrafast lasers, remains an outstanding challenge at the frontier of accelerator physics and ultrafast science. In this Letter, we present the beam physics and experimental demonstration of a new method that, for the first time, enables simultaneous co… ▽ More Generating high-brightness relativistic electron bunches with few-femtosecond duration, while simultaneously achieving few-fs synchronization with ultrafast lasers, remains an outstanding challenge at the frontier of accelerator physics and ultrafast science. In this Letter, we present the beam physics and experimental demonstration of a new method that, for the first time, enables simultaneous control of bunch duration and synchronization with few-fs precision. Timing stabilization is achieved using a tailored high-gradient $α$-magnet that optimizes the correlation between time of flight and momentum, together with a photocathode RF gun designed to suppress the effect of RF-to-laser timing jitter. Compression is realized by manipulating the time-momentum correlation in phase space, primarily through space-charge effects. Sub-5-fs rms bunch duration and synchronization are demonstrated. This method establishes a new regime in electron bunch control, unlocking new capabilities for ultrafast beam physics and applications. △ Less

Submitted 5 August, 2025; originally announced August 2025.

Low-Energy Calibration of SuperCDMS HVeV Cryogenic Silicon Calorimeters Using Compton Steps

Authors: SuperCDMS Collaboration, M. F. Albakry, I. Alkhatib, D. Alonso-Gonźalez, D. W. P. Amaral, J. Anczarski, T. Aralis, T. Aramaki, I. Ataee Langroudy, C. Bathurst, R. Bhattacharyya, A. J. Biffl, P. L. Brink, M. Buchanan, R. Bunker, B. Cabrera, R. Calkins, R. A. Cameron, C. Cartaro, D. G. Cerdeño, Y. -Y. Chang, M. Chaudhuri, J. -H. Chen, R. Chen, N. Chott , et al. (126 additional authors not shown)

Abstract: Cryogenic calorimeters for low-mass dark matter searches have achieved sub-eV energy resolutions, driving advances in both low-energy calibration techniques and our understanding of detector physics. The energy deposition spectrum of gamma rays scattering off target materials exhibits step-like features, known as Compton steps, near the binding energies of atomic electrons. We demonstrate a succes… ▽ More Cryogenic calorimeters for low-mass dark matter searches have achieved sub-eV energy resolutions, driving advances in both low-energy calibration techniques and our understanding of detector physics. The energy deposition spectrum of gamma rays scattering off target materials exhibits step-like features, known as Compton steps, near the binding energies of atomic electrons. We demonstrate a successful use of Compton steps for sub-keV calibration of cryogenic silicon calorimeters, utilizing four SuperCDMS High-Voltage eV-resolution (HVeV) detectors operated with 0 V bias across the crystal. This new calibration at 0 V is compared with the established high-voltage calibration using optical photons. The comparison indicates that the detector response at 0 V is about 30% weaker than expected, highlighting challenges in detector response modeling for low-mass dark matter searches. △ Less

Submitted 9 December, 2025; v1 submitted 4 August, 2025; originally announced August 2025.

Comments: 14 pages + title and references, 13 figures, and 6 table

Journal ref: Phys.Rev.D 112 (2025) 092014

Are There High-Density Deep States in AtomicLayer-Deposited IGZO Thin Film?

Authors: Liankai Zheng, Lijuan Xing, Zhiyu Lin, Wanpeng Zhao, Yuyan Fan, Yulong Dong, Ziheng Wang, Siying Li, Xiuyan Li, Ying Wu, Jeffrey Xu, Mengwei Si

Abstract: It has been well recognized that there exist high-density deep states in IGZO thin films. Many of the device characteristics of IGZO transistors, such as negative bias illumination stability (NBIS),were understood to be related to these deep states. However, in this work, it is found that deep state density (NtD) of atomic-layer-deposited (ALD) IGZO transistors can be an ultra-low value (2.3*10^12… ▽ More It has been well recognized that there exist high-density deep states in IGZO thin films. Many of the device characteristics of IGZO transistors, such as negative bias illumination stability (NBIS),were understood to be related to these deep states. However, in this work, it is found that deep state density (NtD) of atomic-layer-deposited (ALD) IGZO transistors can be an ultra-low value (2.3*10^12 /cm^3) by the proposed NBIS-free light assisted I-V measurements so that the deep states do not affect the I-V characteristics even in subthreshold region. This work also reveals that NBIS is not related to the photoexcitation of electrons in deep states. Our results suggest that the existence of deep states and the impact of deep states on ALD IGZO transistors may need to be revisited. △ Less

Submitted 16 March, 2025; originally announced March 2025.

Experimental Demonstration of Logical Magic State Distillation

Authors: Pedro Sales Rodriguez, John M. Robinson, Paul Niklas Jepsen, Zhiyang He, Casey Duckering, Chen Zhao, Kai-Hsin Wu, Joseph Campo, Kevin Bagnall, Minho Kwon, Thomas Karolyshyn, Phillip Weinberg, Madelyn Cain, Simon J. Evered, Alexandra A. Geim, Marcin Kalinowski, Sophie H. Li, Tom Manovitz, Jesse Amato-Grill, James I. Basham, Liane Bernstein, Boris Braverman, Alexei Bylinskii, Adam Choukri, Robert DeAngelo , et al. (48 additional authors not shown)

Abstract: Realizing universal fault-tolerant quantum computation is a key goal in quantum information science. By encoding quantum information into logical qubits utilizing quantum error correcting codes, physical errors can be detected and corrected, enabling substantial reduction in logical error rates. However, the set of logical operations that can be easily implemented on such encoded qubits is often c… ▽ More Realizing universal fault-tolerant quantum computation is a key goal in quantum information science. By encoding quantum information into logical qubits utilizing quantum error correcting codes, physical errors can be detected and corrected, enabling substantial reduction in logical error rates. However, the set of logical operations that can be easily implemented on such encoded qubits is often constrained, necessitating the use of special resource states known as 'magic states' to implement universal, classically hard circuits. A key method to prepare high-fidelity magic states is to perform 'distillation', creating them from multiple lower fidelity inputs. Here we present the experimental realization of magic state distillation with logical qubits on a neutral-atom quantum computer. Our approach makes use of a dynamically reconfigurable architecture to encode and perform quantum operations on many logical qubits in parallel. We demonstrate the distillation of magic states encoded in d=3 and d=5 color codes, observing improvements of the logical fidelity of the output magic states compared to the input logical magic states. These experiments demonstrate a key building block of universal fault-tolerant quantum computation, and represent an important step towards large-scale logical quantum processors. △ Less

Submitted 19 December, 2024; originally announced December 2024.

Comments: 8+11 pages, 4+4 figures

Journal ref: Nature 645, 620-625 (2025)

AI-Enabled Rapid Assembly of Thousands of Defect-Free Neutral Atom Arrays with Constant-time-overhead

Authors: Rui Lin, Han-Sen Zhong, You Li, Zhang-Rui Zhao, Le-Tian Zheng, Tai-Ran Hu, Hong-Ming Wu, Zhan Wu, Wei-Jie Ma, Yan Gao, Yi-Kang Zhu, Zhao-Feng Su, Wan-Li Ouyang, Yu-Chen Zhang, Jun Rui, Ming-Cheng Chen, Chao-Yang Lu, Jian-Wei Pan

Abstract: Assembling increasingly larger-scale defect-free optical tweezer-trapped atom arrays is essential for quantum computation and quantum simulations based on atoms. Here, we propose an AI-enabled, rapid, constant-time-overhead rearrangement protocol, and we experimentally assemble defect-free 2D and 3D atom arrays with up to 2024 atoms with a constant time cost of 60 ms. The AI model calculates the h… ▽ More Assembling increasingly larger-scale defect-free optical tweezer-trapped atom arrays is essential for quantum computation and quantum simulations based on atoms. Here, we propose an AI-enabled, rapid, constant-time-overhead rearrangement protocol, and we experimentally assemble defect-free 2D and 3D atom arrays with up to 2024 atoms with a constant time cost of 60 ms. The AI model calculates the holograms for real-time atom rearrangement. With precise controls over both position and phase, a high-speed spatial light modulator moves all the atoms simultaneously. This protocol can be readily used to generate defect-free arrays of tens of thousands of atoms with current technologies, and become a useful toolbox for quantum error correction. △ Less

Submitted 19 December, 2024; originally announced December 2024.

Journal ref: Phys. Rev. Lett. 135, 060602 (2025)

Isospectral reduction of the SSH3 lattice and its bulk-edge correspondence

Authors: Qian-Hao Guo, Yang Zhang, Xiao-Huan Wan, Li-Yang Zheng

Abstract: Here, we propose an isospectral reduction (IR) approach for the mapping of a trimer Su-Schrieffer-Heeger (SSH3) lattice into a simplified two-site model, whose coupling dynamics ingeniously results in a precise bulk-edge correspondence of the original lattice. The isospectrally-reduced model has inter-cell couplings with dynamic response to the eigenstate energy, allowing for the control of topolo… ▽ More Here, we propose an isospectral reduction (IR) approach for the mapping of a trimer Su-Schrieffer-Heeger (SSH3) lattice into a simplified two-site model, whose coupling dynamics ingeniously results in a precise bulk-edge correspondence of the original lattice. The isospectrally-reduced model has inter-cell couplings with dynamic response to the eigenstate energy, allowing for the control of topological phase transition by energy. We relate the bulk property of the reduced model to the band topology of the SSH3 lattice, allowing for there distinct topological phases with different number of topological edge state pair. An acoustic SSH3 chain is fabricated for experimental demonstration. The said topological edge state pairs are measured. Our study takes a pivotal step toward the exploration of topology in multiple wave systems, opening up possibilities for advanced control of topological waves. △ Less

Submitted 21 November, 2024; v1 submitted 19 November, 2024; originally announced November 2024.

X point effects on the ideal MHD modes in tokamaks in the description of dual-poloidal-region safety factor

Authors: Linjin Zheng, M. T. Kotschenreuther, F. L. Waelbroeck, M. E. Austin

Abstract: The flux coordinates with dual-region safety factor (q) in the poloidal direction are developed in this work. The X-point effects on the ideal MHD modes in tokamaks are then analyzed using this coordinate system. Since the X-point effects mainly affect the edge region, the modes localized at the tokamak edge are particularly examined. Two types of modes are studied. The first is related to the con… ▽ More The flux coordinates with dual-region safety factor (q) in the poloidal direction are developed in this work. The X-point effects on the ideal MHD modes in tokamaks are then analyzed using this coordinate system. Since the X-point effects mainly affect the edge region, the modes localized at the tokamak edge are particularly examined. Two types of modes are studied. The first is related to the conventional peeling or peeling-ballooning modes. The mode existence aligned with the local magnetic field in the poloidally core region, as observed experimentally, is confirmed. The X points are shown to contribute to a stabilizing effect for the conventionally treated modes with the surface-averaged q and with the tokamak edge portion truncated. The other is the axisymmetric modes localized in the vicinity of X points, which can affect the cross-field-line transport near the X points. The existence of axisymmetric modes points to the possibility of applying a toroidally axisymmetric resonant magnetic perturbation (RMP) in the X-point area for mitigating the edge localized modes, which can be an alternative to the current RMP design. The dual q description also has important implications for the existing non-axisymmetric RMP concept. It helps to understand why the RMP suppression of edge localized modes is difficult to achieve in the double-null tokamak configurations and points to the possibility of further improving the current RMP concept by considering the alignment to the local q. △ Less

Submitted 31 October, 2024; originally announced November 2024.

A Flat Plasmonic Biosensing Interface on Optical Fiber End-Facet via SPP-MIM Hybridization

Authors: Chenjia He, Xiaqing Sun, Hao Zhong, Qingfeng Meng, Xuetong Zhou, Sihang Liu, Li Zheng, Xiangyang Kong, Shengfu Chen, Shengce Tao, Tian Yang

Abstract: We found that the specific dispersion of metal-insulator-metal (MIM) waveguide allows the hybridization of surface plasmon polaritons (SPPs) and the waveguide, which is not possible with dielectric waveguides. The SPP-MIM hybridization structure forms such a meta-film that integrates the previously incompatible respective merits of SPR and LSPR, including flat interfaces, high sensitivities, short… ▽ More We found that the specific dispersion of metal-insulator-metal (MIM) waveguide allows the hybridization of surface plasmon polaritons (SPPs) and the waveguide, which is not possible with dielectric waveguides. The SPP-MIM hybridization structure forms such a meta-film that integrates the previously incompatible respective merits of SPR and LSPR, including flat interfaces, high sensitivities, short evanescent fields and easy coupling with confined light. On the other hand, to achieve stable and reproducible performance is one of the greatest unresolved challenges for the development of nanophotonic biosensors. We point out that the key is to obtain well-controlled biomolecular behaviors using simple physical interfaces, for which the SPP-MIM meta-film provides a capable solution. We embed the SPP-MIM meta-film with a plasmonic crystal cavity and integrate it on a single-mode fiber's end-facet to detect biomolecular interactions. This device demonstrates highly reproducible sensorgrams and convincing detection of biotinylated proteins at down to 30 fM, with the sensorgrams following the Langmuir model. By unprecedentedly having both high sensitivity and high reproducibility, our device proposal provides a comprehensive solution for optical fiber-tip plasmonic devices to turn into a useful industrial biosensing technology. △ Less

Submitted 19 October, 2024; originally announced October 2024.

Comments: article + supplementary information

Experiment Research on Feasibility of In-Situ Plasma Cleaning in Normal-conducting Copper Cavities

Authors: Qianxu Xia, Lianmin Zheng, Yingchao Du

Abstract: To assess the feasibility of in-situ plasma cleaning for copper cavities, a 13.56 MHz inductively coupled plasma platform with a built-in coil was developed at Tsinghua University. Experiments were conducted using this platform to optimize plasma discharge parameters and procedures specific to copper cavities. The results indicate that the "Ar/O + Ar/H method" significantly enhances the work funct… ▽ More To assess the feasibility of in-situ plasma cleaning for copper cavities, a 13.56 MHz inductively coupled plasma platform with a built-in coil was developed at Tsinghua University. Experiments were conducted using this platform to optimize plasma discharge parameters and procedures specific to copper cavities. The results indicate that the "Ar/O + Ar/H method" significantly enhances the work function of the copper surface while reducing field enhancement effects induced by surface burrs. Consequently, this study confirms that in-situ plasma cleaning effectively mitigates field emission within copper cavities, thereby enhancing the stability and acceleration gradient of the accelerator system. △ Less

Submitted 11 October, 2024; v1 submitted 26 August, 2024; originally announced August 2024.

Generation of squeezed vacuum state in the millihertz frequency band

Authors: Li Gao, Li-ang Zheng, Bo Lu, Shaoping Shi, Long Tian, Yaohui Zheng

Abstract: The detection of gravitational waves has ushered in a new era of observing the universe. Quantum resource advantages offer significant enhancements to the sensitivity of gravitational wave observatories. While squeezed states for ground-based gravitational wave detection have received marked attention, the generation of squeezed states suitable for mid-to-low-frequency detection has remained unexp… ▽ More The detection of gravitational waves has ushered in a new era of observing the universe. Quantum resource advantages offer significant enhancements to the sensitivity of gravitational wave observatories. While squeezed states for ground-based gravitational wave detection have received marked attention, the generation of squeezed states suitable for mid-to-low-frequency detection has remained unexplored. To address the gap in squeezed state optical fields at ultra-low frequencies, we report on the first direct observation of a squeezed vacuum field until Fourier frequency of 4 millihertz with the quantum noise reduction of up to 8 dB, by the employment of a multiple noise suppression scheme. Our work provides quantum resources for future gravitational wave observatories, facilitating the development of quantum precision measurement. △ Less

Submitted 20 August, 2024; originally announced August 2024.

Comments: 17 pages,4 figures,1 table and 50 Refs. To be published in Light: Science & Applications

Journal ref: Light: Science & Applications 13, 294 (2024)

Light Dark Matter Constraints from SuperCDMS HVeV Detectors Operated Underground with an Anticoincidence Event Selection

Authors: SuperCDMS Collaboration, M. F. Albakry, I. Alkhatib, D. Alonso-González, D. W. P. Amaral, J. Anczarski, T. Aralis, T. Aramaki, I. J. Arnquist, I. Ataee Langroudy, E. Azadbakht, C. Bathurst, R. Bhattacharyya, A. J. Biffl, P. L. Brink, M. Buchanan, R. Bunker, B. Cabrera, R. Calkins, R. A. Cameron, C. Cartaro, D. G. Cerdeño, Y. -Y. Chang, M. Chaudhuri, J. -H. Chen , et al. (117 additional authors not shown)

Abstract: This article presents constraints on dark-matter-electron interactions obtained from the first underground data-taking campaign with multiple SuperCDMS HVeV detectors operated in the same housing. An exposure of 7.63 g-days is used to set upper limits on the dark-matter-electron scattering cross section for dark matter masses between 0.5 and 1000 MeV/$c^2$, as well as upper limits on dark photon k… ▽ More This article presents constraints on dark-matter-electron interactions obtained from the first underground data-taking campaign with multiple SuperCDMS HVeV detectors operated in the same housing. An exposure of 7.63 g-days is used to set upper limits on the dark-matter-electron scattering cross section for dark matter masses between 0.5 and 1000 MeV/$c^2$, as well as upper limits on dark photon kinetic mixing and axion-like particle axioelectric coupling for masses between 1.2 and 23.3 eV/$c^2$. Compared to an earlier HVeV search, sensitivity was improved as a result of an increased overburden of 225 meters of water equivalent, an anticoincidence event selection, and better pile-up rejection. In the case of dark-matter-electron scattering via a heavy mediator, an improvement by up to a factor of 25 in cross-section sensitivity was achieved. △ Less

Submitted 5 September, 2024; v1 submitted 10 July, 2024; originally announced July 2024.

Comments: 7 pages + title and references, 4 figures, and 1 table

Journal ref: Phys. Rev. D, 111 012006 (2025)

Compact ultra-broadband light coupling on chip via nonadiabatic pumping

Authors: Weiwei Liu, Chijun Li, Bing Wang, Tianyan Chai, Lingzhi Zheng, Zhuoxiong Liu, Haoru Zhang, Shuaifei Ren, Xiaohong Li, Cheng Zeng, Jinsong Xia, Peixiang Lu

Abstract: Enlarging bandwidth capacity of the integrated photonic systems demands efficient and broadband light coupling among optical elements, which has been a vital issue in integrated photonics. Here, we have developed a compact ultra-broadband light coupling strategy based on nonadiabatic pumping in coupled optical waveguides, and experimentally demonstrated the designs in thin-film lithium niobate on… ▽ More Enlarging bandwidth capacity of the integrated photonic systems demands efficient and broadband light coupling among optical elements, which has been a vital issue in integrated photonics. Here, we have developed a compact ultra-broadband light coupling strategy based on nonadiabatic pumping in coupled optical waveguides, and experimentally demonstrated the designs in thin-film lithium niobate on insulator (LNOI) platform. We found that nonadiabatic transition would produce a decreased dispersion of the phases related to eigenstates in the waveguides. As a consequence, we realized high-efficiency directional transfer between edgestates for various wavelengths covering a 1-dB bandwidth of ~320 nm in experiment (>400 nm in simulation), with a coupling length (~50 μm) approximately 1/10 of that required in the adiabatic regime. Furthermore, we have constructed complex functional devices including beamsplitter and multiple-level cascaded networks for broadband light routing and splitting. Our work preserves significant advantages simultaneously in extending the operation bandwidth and minimizing the footprint, which demonstrates great potential for large-scale and compact photonic integration on chip. △ Less

Submitted 4 July, 2024; originally announced July 2024.

Farey tree locking of terahertz semiconductor laser frequency combs

Authors: Guibin Liu, Xuhong Ma, Kang Zhou, Binbin Liu, Lulu Zheng, Xianglong Bi, Shumin Wu, Yanming Lu, Ziping Li, Wenjian Wan, Zhenzhen Zhang, Junsong Peng, Ya Zhang, Heping Zeng, Hua Li

Abstract: Frequency combs show various applications in molecular fingerprinting, imaging, communications, and so on. In the terahertz frequency range, semiconductor-based quantum cascade lasers (QCLs) are ideal platforms for realizing the frequency comb operation. Although self-started frequency comb operation can be obtained in free-running terahertz QCLs due to the four-wave mixing locking effects, resona… ▽ More Frequency combs show various applications in molecular fingerprinting, imaging, communications, and so on. In the terahertz frequency range, semiconductor-based quantum cascade lasers (QCLs) are ideal platforms for realizing the frequency comb operation. Although self-started frequency comb operation can be obtained in free-running terahertz QCLs due to the four-wave mixing locking effects, resonant/off-resonant microwave injection, phase locking, and femtosecond laser based locking techniques have been widely used to broaden and stabilize terahertz QCL combs. These active locking methods indeed show significant effects on the frequency stabilization of terahertz QCL combs, but they simultaneously have drawbacks, such as introducing large phase noise and requiring complex optical coupling and/or electrical circuits. Here, we demonstrate Farey tree locking of terahertz QCL frequency combs under microwave injection. The frequency competition between the Farey fraction frequency and the cavity round-trip frequency results in the frequency locking of terahertz QCL combs, and the Farey fraction frequencies can be accurately anticipated based on the downward trend of the Farey tree hierarchy. Furthermore, dual-comb experimental results show that the phase noise of the dual-comb spectral lines is significantly reduced by employing the Farey tree locking method. These results pave the way to deploying compact and low phase noise terahertz frequency comb sources. △ Less

Submitted 19 June, 2024; originally announced June 2024.

Comments: 22 page, 7 figures. Light: Science & Applications, 2025

Prospects of negative triangularity tokamak for advanced steady-state confinement of fusion plasmas

Authors: Linjin Zheng, M. T. Kotschenreuther, F. L. Waelbroeck, M. E. Austin, W. L. Rowan, P. Valanju, X. Liu

Abstract: The steady-state confinement, beta limit, and divertor heat load are among the most concerned issues for toroidal confinement of fusion plasmas. In this work, we show that the negative triangularity tokamak has promising prospects to address these issues. We first demonstrate that the negative triangularity tokamak generates the filed line rotation transform more effectively. This brings bright pr… ▽ More The steady-state confinement, beta limit, and divertor heat load are among the most concerned issues for toroidal confinement of fusion plasmas. In this work, we show that the negative triangularity tokamak has promising prospects to address these issues. We first demonstrate that the negative triangularity tokamak generates the filed line rotation transform more effectively. This brings bright prospects for the advanced steady-state tokamak scenario. Given this, the stability and confinement features of negative triangularity tokamak are investigated. We point out that the negative triangularity configuration with a broad pressure profile is indeed more unstable for low-n magnetohydrodynamic modes than the positive triangularity case so that the H-mode confinement can hardly be achieved in this configuration, where n is the toroidal mode number. Nevertheless, we found that the negative triangularity configuration with high bootstrap current fraction, high poloidal beta, and peaked pressure profiles can achieve higher normalized beta for low-n modes than the positive triangularity case. In a certain parameter domain, the normalized beta can reach about twice the extended Troyon limit, while the same computation indicates that the positive triangularity configuration is indeed constrained by the Troyon limit. This shows that the negative triangularity tokamaks are not only favorable for divertor design to avoid the edge localized modes but also can have promising prospects for advanced steady-state confinement of fusion plasmas in high beta. △ Less

Submitted 27 January, 2024; originally announced January 2024.

Comments: 38 pages, 14 figures

Automated interpretation of congenital heart disease from multi-view echocardiograms

Authors: Jing Wang, Xiaofeng Liu, Fangyun Wang, Lin Zheng, Fengqiao Gao, Hanwen Zhang, Xin Zhang, Wanqing Xie, Binbin Wang

Abstract: Congenital heart disease (CHD) is the most common birth defect and the leading cause of neonate death in China. Clinical diagnosis can be based on the selected 2D key-frames from five views. Limited by the availability of multi-view data, most methods have to rely on the insufficient single view analysis. This study proposes to automatically analyze the multi-view echocardiograms with a practical… ▽ More Congenital heart disease (CHD) is the most common birth defect and the leading cause of neonate death in China. Clinical diagnosis can be based on the selected 2D key-frames from five views. Limited by the availability of multi-view data, most methods have to rely on the insufficient single view analysis. This study proposes to automatically analyze the multi-view echocardiograms with a practical end-to-end framework. We collect the five-view echocardiograms video records of 1308 subjects (including normal controls, ventricular septal defect (VSD) patients and atrial septal defect (ASD) patients) with both disease labels and standard-view key-frame labels. Depthwise separable convolution-based multi-channel networks are adopted to largely reduce the network parameters. We also approach the imbalanced class problem by augmenting the positive training samples. Our 2D key-frame model can diagnose CHD or negative samples with an accuracy of 95.4\%, and in negative, VSD or ASD classification with an accuracy of 92.3\%. To further alleviate the work of key-frame selection in real-world implementation, we propose an adaptive soft attention scheme to directly explore the raw video data. Four kinds of neural aggregation methods are systematically investigated to fuse the information of an arbitrary number of frames in a video. Moreover, with a view detection module, the system can work without the view records. Our video-based model can diagnose with an accuracy of 93.9\% (binary classification), and 92.1\% (3-class classification) in a collected 2D video testing set, which does not need key-frame selection and view annotation in testing. The detailed ablation study and the interpretability analysis are provided. △ Less

Submitted 30 November, 2023; originally announced November 2023.

Comments: Published in Medical Image Analysis

Journal ref: Medical Image Analysis (Volume 69, April 2021, 101942)

Mapping electrostatic potential in electrolyte solution

Authors: Bo Huang, Yining Yang, Ruinong Han, Keke Chen, Zhiyuan Wang, Longteng Yun, Yian Wang, Haowei Chen, Yingchao Du, Yuxia Hao, Peng Lv, Haoran Ma, Pengju Ji, Yuemei Tan, Lianmin Zheng, Lihong Liu, Renkai Li, Jie Yang

Abstract: Mapping the electrostatic potential (ESP) distribution around ions in electrolyte solution is crucial for the establishment of a microscopic understanding of electrolyte solution properties. For solutions in the bulk phase, it has not been possible to measure the ESP distribution on Angstrom scale. Here we show that liquid electron scattering experiment using state-of-the-art relativistic electron… ▽ More Mapping the electrostatic potential (ESP) distribution around ions in electrolyte solution is crucial for the establishment of a microscopic understanding of electrolyte solution properties. For solutions in the bulk phase, it has not been possible to measure the ESP distribution on Angstrom scale. Here we show that liquid electron scattering experiment using state-of-the-art relativistic electron beam can be used to measure the Debye screening length of aqueous LiCl, KCl, and KI solutions across a wide range of concentrations. We observe that the Debye screening length is long-ranged at low concentration and short-ranged at high concentration, providing key insight into the decades-long debate over whether the impact of ions in water is long-ranged or short-ranged. In addition, we show that the measured ESP can be used to retrieve the non-local dielectric function of electrolyte solution, which can serve as a promising route to investigate the electrostatic origin of special ion effects. Our observations show that, interaction, as one of the two fundamental perspectives for understanding electrolyte solution, can provide much richer information than structure. △ Less

Submitted 1 February, 2024; v1 submitted 1 November, 2023; originally announced November 2023.

Comments: The small-angle signal in Fig. 2 C-H is highly likely to be an experimental artifact, due to that the electron beam is placed too close to the edge of the liquid sheet. This artifact invalidates the main conclusion of the paper

Rheological synergistic thermal conductivity of CMC-based Fe3O4 and Al2O3 nanofluids in shear flow fields

Authors: Shengna Liu, Liancun Zheng

Abstract: In this paper, considering the variation of the viscous dissipative heat in the transfer direction, a new theoretical formula for thermal conductivity measurement was proposed based on the energy equation of the rotational Couette flow field. This theoretical formula shows that thermal conductivity and rheology have a synergistic effect. Based on this theoretical formula, the rheological synergist… ▽ More In this paper, considering the variation of the viscous dissipative heat in the transfer direction, a new theoretical formula for thermal conductivity measurement was proposed based on the energy equation of the rotational Couette flow field. This theoretical formula shows that thermal conductivity and rheology have a synergistic effect. Based on this theoretical formula, the rheological synergistic thermal conductivity of CMC-based Fe3O4 nanofluids and Al2O3 nanofluids was experimentally investigated. The experimental results show that the thermal conductivity rises with the increase of shear rate and volume fraction, moreover, volume fraction and shear rate have mutually reinforcing effects on thermal conductivity enhancement. Non-Newtonian effects of rheology and heat transfer reduce with shear rate and increase with volume fraction, with consistent synergistic effects. According to the experimental data, the expressions of the thermal conductivity and dynamic viscosity of these two nanofluids as functions of shear rate and volume fraction were presented. △ Less

Submitted 26 October, 2023; originally announced October 2023.

Response to "Comment on `Modification of Lie's transform perturbation theory for charged particle motion in a magnetic field'" [Phys. Plasmas 30, 104701 (2023)]

Authors: Linjin Zheng

Abstract: Dr. Brizard's comment on my work is based on a conceived procedure that does not come from my work. The defense of his claim that the modification of the so-called standard Lie's transform theory is unnecessary is also unsupported. This response reveals in detail the inconsistency issues in the so-called standard Lie's transform theory by analyzing both its results and root causes. The problem in… ▽ More Dr. Brizard's comment on my work is based on a conceived procedure that does not come from my work. The defense of his claim that the modification of the so-called standard Lie's transform theory is unnecessary is also unsupported. This response reveals in detail the inconsistency issues in the so-called standard Lie's transform theory by analyzing both its results and root causes. The problem in the so-called standard Lie's transform theory is beyond the issue to take into account the ordering difference between the guiding center motion and gyromotion. The inconsistent commutation of derivative and limit causes another issue. Besides, the so-called standard Lie's transform formulation leads to an unnecessarily lengthy and tedious derivation process for a one or two page task under the singular (or renormalized) formalism described in my paper. △ Less

Submitted 4 October, 2023; originally announced October 2023.

Comments: 11 pages

MSC Class: 76M45; 00A69; 11F22

Journal ref: Phys. Plasmas {\bf 30} 104702 (2023)

Photonic Integrated Neuro-Synaptic Core for Convolutional Spiking Neural Network

Authors: Shuiying Xiang, Yuechun Shi, Yahui Zhang, Xingxing Guo, Ling Zheng, Yanan Han, Yuna Zhang, Ziwei Song, Dianzhuang Zheng, Tao Zhang, Hailing Wang, Xiaojun Zhu, Xiangfei Chen, Min Qiu, Yichen Shen, Wanhua Zheng, Yue Hao

Abstract: Neuromorphic photonic computing has emerged as a competitive computing paradigm to overcome the bottlenecks of the von-Neumann architecture. Linear weighting and nonlinear spiking activation are two fundamental functions of a photonic spiking neural network (PSNN). However, they are separately implemented with different photonic materials and devices, hindering the large-scale integration of PSNN.… ▽ More Neuromorphic photonic computing has emerged as a competitive computing paradigm to overcome the bottlenecks of the von-Neumann architecture. Linear weighting and nonlinear spiking activation are two fundamental functions of a photonic spiking neural network (PSNN). However, they are separately implemented with different photonic materials and devices, hindering the large-scale integration of PSNN. Here, we propose, fabricate and experimentally demonstrate a photonic neuro-synaptic chip enabling the simultaneous implementation of linear weighting and nonlinear spiking activation based on a distributed feedback (DFB) laser with a saturable absorber (DFB-SA). A prototypical system is experimentally constructed to demonstrate the parallel weighted function and nonlinear spike activation. Furthermore, a four-channel DFB-SA array is fabricated for realizing matrix convolution of a spiking convolutional neural network, achieving a recognition accuracy of 87% for the MNIST dataset. The fabricated neuro-synaptic chip offers a fundamental building block to construct the large-scale integrated PSNN chip. △ Less

Submitted 5 June, 2023; originally announced June 2023.

Modification of Lie's transform perturbation theory for charged particle motion in a magnetic field

Authors: Linjin Zheng

Abstract: It is pointed out that the conventional Lie transform perturbation theory for the guiding center motion of charged particles in a magnetic field needs to be modified for ordering inconsistency. There are two reasons. First, the ordering difference between the temporal variation of gyrophase and that of the other phase space coordinates needs to be taken into account. Second, it is also important t… ▽ More It is pointed out that the conventional Lie transform perturbation theory for the guiding center motion of charged particles in a magnetic field needs to be modified for ordering inconsistency. There are two reasons. First, the ordering difference between the temporal variation of gyrophase and that of the other phase space coordinates needs to be taken into account. Second, it is also important to note that the parametric limit of the derivative of a function is not equivalent to the derivative of the limit function. When these facts are taken into account, the near identity transformation rule for one form related to the Lagrangian is modified. With the modified near identity transformation rule, the drift motion of charged particles can be described in the first order, instead of in the second order and beyond through a tedious expansion process as in the conventional formulation. This resolves the discrepancy between the direct and Lie transform treatments in the Lagrangian perturbation theory for charged particle motion in a magnetic field. △ Less

Submitted 7 April, 2023; v1 submitted 6 April, 2023; originally announced April 2023.

Comments: 18 pages

STCF Conceptual Design Report: Volume 1 -- Physics & Detector

Authors: M. Achasov, X. C. Ai, R. Aliberti, L. P. An, Q. An, X. Z. Bai, Y. Bai, O. Bakina, A. Barnyakov, V. Blinov, V. Bobrovnikov, D. Bodrov, A. Bogomyagkov, A. Bondar, I. Boyko, Z. H. Bu, F. M. Cai, H. Cai, J. J. Cao, Q. H. Cao, Z. Cao, Q. Chang, K. T. Chao, D. Y. Chen, H. Chen , et al. (413 additional authors not shown)

Abstract: The Super $τ$-Charm facility (STCF) is an electron-positron collider proposed by the Chinese particle physics community. It is designed to operate in a center-of-mass energy range from 2 to 7 GeV with a peak luminosity of $0.5\times 10^{35}{\rm cm}^{-2}{\rm s}^{-1}$ or higher. The STCF will produce a data sample about a factor of 100 larger than that by the present $τ$-Charm factory -- the BEPCII,… ▽ More The Super $τ$-Charm facility (STCF) is an electron-positron collider proposed by the Chinese particle physics community. It is designed to operate in a center-of-mass energy range from 2 to 7 GeV with a peak luminosity of $0.5\times 10^{35}{\rm cm}^{-2}{\rm s}^{-1}$ or higher. The STCF will produce a data sample about a factor of 100 larger than that by the present $τ$-Charm factory -- the BEPCII, providing a unique platform for exploring the asymmetry of matter-antimatter (charge-parity violation), in-depth studies of the internal structure of hadrons and the nature of non-perturbative strong interactions, as well as searching for exotic hadrons and physics beyond the Standard Model. The STCF project in China is under development with an extensive R\&D program. This document presents the physics opportunities at the STCF, describes conceptual designs of the STCF detector system, and discusses future plans for detector R\&D and physics case studies. △ Less

Submitted 5 October, 2023; v1 submitted 28 March, 2023; originally announced March 2023.

Journal ref: Front. Phys. 19(1), 14701 (2024)

First measurement of the nuclear-recoil ionization yield in silicon at 100 eV

Authors: M. F. Albakry, I. Alkhatib, D. Alonso, D. W. P. Amaral, P. An, T. Aralis, T. Aramaki, I. J. Arnquist, I. Ataee Langroudy, E. Azadbakht, S. Banik, P. S. Barbeau, C. Bathurst, R. Bhattacharyya, P. L. Brink, R. Bunker, B. Cabrera, R. Calkins, R. A. Cameron, C. Cartaro, D. G. Cerdeño, Y. -Y. Chang, M. Chaudhuri, R. Chen, N. Chott , et al. (115 additional authors not shown)

Abstract: We measured the nuclear--recoil ionization yield in silicon with a cryogenic phonon-sensitive gram-scale detector. Neutrons from a mono-energetic beam scatter off of the silicon nuclei at angles corresponding to energy depositions from 4\,keV down to 100\,eV, the lowest energy probed so far. The results show no sign of an ionization production threshold above 100\,eV. These results call for furthe… ▽ More We measured the nuclear--recoil ionization yield in silicon with a cryogenic phonon-sensitive gram-scale detector. Neutrons from a mono-energetic beam scatter off of the silicon nuclei at angles corresponding to energy depositions from 4\,keV down to 100\,eV, the lowest energy probed so far. The results show no sign of an ionization production threshold above 100\,eV. These results call for further investigation of the ionization yield theory and a comprehensive determination of the detector response function at energies below the keV scale. △ Less

Submitted 3 March, 2023; originally announced March 2023.

Journal ref: Physical Review Letters 131.9 (2023): 091801

Topologically invisible defects in chiral mirror lattices

Authors: Antonin Coutant, Li-Yang Zheng, Vassos Achilleos, Olivier Richoux, Georgios Theocharis, Vincent Pagneux

Abstract: One of the hallmark of topological insulators is having conductivity properties that are unaffected by the possible presence of defects. In this work, we go beyond backscattering immunity and obtain topological invisibility across defects or disorder. Using a combination of chiral and mirror symmetry, the transmission coefficient is guaranteed to be unity. Importantly, but no phase shift is induce… ▽ More One of the hallmark of topological insulators is having conductivity properties that are unaffected by the possible presence of defects. In this work, we go beyond backscattering immunity and obtain topological invisibility across defects or disorder. Using a combination of chiral and mirror symmetry, the transmission coefficient is guaranteed to be unity. Importantly, but no phase shift is induced making the defect completely invisible. Many lattices possess the chiral-mirror symmetry, and we choose to demonstrate the principle on an hexagonal lattice model with Kekule distortion displaying topological edge waves, and we show analytically and numerically that the transmission across symmetry preserving defects is unity. We then realize this lattice in an acoustic system, and confirm the invisibility with numerical experiments. We foresee that the versatility of our model will trigger new experiments to observe topological invisibility in various wave systems, such as photonics, cold atoms or elastic waves. △ Less

Submitted 21 November, 2024; v1 submitted 3 March, 2023; originally announced March 2023.

Comments: 9+6 pages, 6+5 figures. Few minor corrections and clarifications. Match published version

Journal ref: Advanced Physics Research 3 no. 4, (2024) 2300102

Observation of Q-switched and continuous wave regimes with mode-hopping in Er-doped fiber lasers incorporating a dynamic population grating

Authors: Zengrun Wen, Xiulin Fan, Kaile Wang, Weiming Wang, Song Gao, Wenjing Hao, Yuanmei Gao, Yangjian Cai, Liren Zheng

Abstract: Dynamic population gratings (DPGs) in rare-earth doped fibers are prevalent devices in fiber lasers for the production of single-longitudinal-mode emission, Q-switched pulses, and wavelength self-sweeping regimes. This study presents a transition from Q-switched state to continuous wave (CW) state, accompanying irregular mode-hopping, in an erbium-doped fiber laser with a heavily-doped DPG centere… ▽ More Dynamic population gratings (DPGs) in rare-earth doped fibers are prevalent devices in fiber lasers for the production of single-longitudinal-mode emission, Q-switched pulses, and wavelength self-sweeping regimes. This study presents a transition from Q-switched state to continuous wave (CW) state, accompanying irregular mode-hopping, in an erbium-doped fiber laser with a heavily-doped DPG centered at 1549.95 nm. Our results demonstrate that the transition between these two states can be achieved by adjusting the pump power. The repetition frequency of the Q-switched pulse increases monotonically with the increasing pump power, while the pulse duration initially narrows and then expands because the reduced peak intensity weakens the nonlinear effect. Additionally, modulation peaks are evident on both the Q-switched pulse train and the CW background, which are induced by the irregular mode-hopping caused by the DPG. Furthermore, we observe that the central wavelength fluctuates within a range of 0.05 nm. These results provide valuable insight into the DPG effect in heavily-doped fibers. △ Less

Submitted 23 February, 2023; originally announced February 2023.

ATEQ: Adaptive Toroidal Equilibrium code

Authors: Linjin Zheng, M. T. Kotschenreuther, F. L. Waelbroeck, Y. Todo

Abstract: A radially adaptive numerical scheme is developed to solve the Grad-Shafranov equation for axisymmetric magnetohydrodynamic equilibrium. A decomposition with independent solutions is employed in the radial direction and Fourier decomposition is used in the poloidal direction. The independent solutions are then obtained using an adaptive shooting scheme together with the multi-region matching techn… ▽ More A radially adaptive numerical scheme is developed to solve the Grad-Shafranov equation for axisymmetric magnetohydrodynamic equilibrium. A decomposition with independent solutions is employed in the radial direction and Fourier decomposition is used in the poloidal direction. The independent solutions are then obtained using an adaptive shooting scheme together with the multi-region matching technique in the radial direction. Accordingly, the Adaptive Toroidal Equilibrium (ATEQ) code is constructed for axisymmetric equilibrium studies. The adaptive numerical scheme in the radial direction improves considerably the accuracy of the equilibrium solution. The decomposition with independent solutions effectively reduces the matrix size in solving the magnetohydrodynamic equilibrium problem. The reduction of the matrix size is about an order of magnitude as compared with the conventional radially grid-based numerical schemes. Also, in this ATEQ numerical scheme, no matter how accuracy in the radial direction is imposed, the size of the matrices basically does not change. The small matrix size scheme gives ATEQ more flexibility to address the requirement of the number of Fourier components in the poloidal direction in the tough equilibrium problems. These two unique features, the adaptive shooting and small matrix size, make ATEQ useful to improve tokamak equilibrium solutions. △ Less

Submitted 5 January, 2023; originally announced January 2023.

Journal ref: Physics of Plasmas 29, 072503 (2022)

Nested sampling statistical errors

Authors: Andrew Fowlie, Qiao Li, Huifang Lv, Yecheng Sun, Jia Zhang, Le Zheng

Abstract: Nested sampling (NS) is a popular algorithm for Bayesian computation. We investigate statistical errors in NS both analytically and numerically. We show two analytic results. First, we show that the leading terms in Skilling's expression using information theory match the leading terms in Keeton's expression from an analysis of moments. This approximate agreement was previously only known numerica… ▽ More Nested sampling (NS) is a popular algorithm for Bayesian computation. We investigate statistical errors in NS both analytically and numerically. We show two analytic results. First, we show that the leading terms in Skilling's expression using information theory match the leading terms in Keeton's expression from an analysis of moments. This approximate agreement was previously only known numerically and was somewhat mysterious. Second, we show that the uncertainty in single NS runs approximately equals the standard deviation in repeated NS runs. Whilst intuitive, this was previously taken for granted. We close by investigating our results and their assumptions in several numerical examples, including cases in which NS uncertainties increase without bound. △ Less

Submitted 6 November, 2022; originally announced November 2022.

Comments: 12 pages + appendices, 3 figures

ATHENA Detector Proposal -- A Totally Hermetic Electron Nucleus Apparatus proposed for IP6 at the Electron-Ion Collider

Authors: ATHENA Collaboration, J. Adam, L. Adamczyk, N. Agrawal, C. Aidala, W. Akers, M. Alekseev, M. M. Allen, F. Ameli, A. Angerami, P. Antonioli, N. J. Apadula, A. Aprahamian, W. Armstrong, M. Arratia, J. R. Arrington, A. Asaturyan, E. C. Aschenauer, K. Augsten, S. Aune, K. Bailey, C. Baldanza, M. Bansal, F. Barbosa, L. Barion , et al. (415 additional authors not shown)

Abstract: ATHENA has been designed as a general purpose detector capable of delivering the full scientific scope of the Electron-Ion Collider. Careful technology choices provide fine tracking and momentum resolution, high performance electromagnetic and hadronic calorimetry, hadron identification over a wide kinematic range, and near-complete hermeticity. This article describes the detector design and its e… ▽ More ATHENA has been designed as a general purpose detector capable of delivering the full scientific scope of the Electron-Ion Collider. Careful technology choices provide fine tracking and momentum resolution, high performance electromagnetic and hadronic calorimetry, hadron identification over a wide kinematic range, and near-complete hermeticity. This article describes the detector design and its expected performance in the most relevant physics channels. It includes an evaluation of detector technology choices, the technical challenges to realizing the detector and the R&D required to meet those challenges. △ Less

Submitted 13 October, 2022; originally announced October 2022.

Journal ref: JINST 17 (2022) 10, P10019

A Graph Neural Network-Based Approach to XANES Data Analysis

Authors: Fei Zhan, Lirong Zheng, Haodong Yao, Zhi Geng, Can Yu, Xue Han, Xueqi Song, Shuguang Chen, Haifeng Zhao

Abstract: X-ray absorption spectroscopy (XAS) is an indispensable tool to characterize the atomic-scale three-dimensional local structure of the system, in which XANES is the most important energy region to reflect the three-dimensional structure. However quantitative analysis of three-dimensional structure from XANES requires users to have a deep understanding and accurate judgment of structural informatio… ▽ More X-ray absorption spectroscopy (XAS) is an indispensable tool to characterize the atomic-scale three-dimensional local structure of the system, in which XANES is the most important energy region to reflect the three-dimensional structure. However quantitative analysis of three-dimensional structure from XANES requires users to have a deep understanding and accurate judgment of structural information and summarize several structural parameters, which is often difficult to achieve. In this work, We construct \textbf{physics-informed Graph neural network} and \textbf{Transformer} models for calculating XANES from the input three-dimensional structure; we improve the efficiency of the model based on the physical meaning of XAS; then we combine the model and optimization algorithm to fit the three-dimensional structure of given system. This method does not require users to summarize the structural parameters, has wide application range. It can be applied to the three-dimensional structure analysis of solid materials and has positive significance for the study of structure-function relationship in the fields of energy and catalysis. In addition, this method is expected to be developed into an online three-dimensional structure analysis method for XAS related beamlines. △ Less

Submitted 1 March, 2026; v1 submitted 7 May, 2022; originally announced May 2022.

Journal ref: J.Phys.Chem.A2025,129,4,874-884

BeAGLE: Benchmark $e$A Generator for LEptoproduction in high energy lepton-nucleus collisions

Authors: Wan Chang, Elke-Caroline Aschenauer, Mark D. Baker, Alexander Jentsch, Jeong-Hun Lee, Zhoudunming Tu, Zhongbao Yin, Liang Zheng

Abstract: The upcoming Electron-Ion Collider (EIC) will address several outstanding puzzles in modern nuclear physics. Topics such as the partonic structure of nucleons and nuclei, the origin of their mass and spin, among others, can be understood via the study of high energy electron-proton ($ep$) and electron-nucleus ($e$A) collisions. Achieving the scientific goals of the EIC will require a novel electro… ▽ More The upcoming Electron-Ion Collider (EIC) will address several outstanding puzzles in modern nuclear physics. Topics such as the partonic structure of nucleons and nuclei, the origin of their mass and spin, among others, can be understood via the study of high energy electron-proton ($ep$) and electron-nucleus ($e$A) collisions. Achieving the scientific goals of the EIC will require a novel electron-hadron collider and detectors capable to perform high-precision measurements, but also dedicated tools to model and interpret the data. To aid in the latter, we present a general-purpose $e$A Monte Carlo (MC) generator - BeAGLE. In this paper, we provide a general description of the models integrated into BeAGLE, applications of BeAGLE in $e$A physics, implications for detector requirements at the EIC, and the tuning of the parameters in BeAGLE based on available experimental data. Specifically, we focus on a selection of model and data comparisons in particle production in both $ep$ and $e$A collisions, where baseline particle distributions provide essential information to characterize the event. In addition, we investigate the collision geometry determination in $e$A collisions, which could be used as an experimental tool for varying the nuclear density. △ Less

Submitted 13 April, 2022; originally announced April 2022.

Comments: Manuscript with 20 pages, 16 figures, and 3 tables

Investigating the sources of low-energy events in a SuperCDMS-HVeV detector

Authors: SuperCDMS Collaboration, M. F. Albakry, I. Alkhatib, D. W. P. Amaral, T. Aralis, T. Aramaki, I. J. Arnquist, I. Ataee Langroudy, E. Azadbakht, S. Banik, C. Bathurst, D. A. Bauer, R. Bhattacharyya, P. L. Brink, R. Bunker, B. Cabrera, R. Calkins, R. A. Cameron, C. Cartaro, D. G. Cerdeño, Y. -Y. Chang, M. Chaudhuri, R. Chen, N. Chott, J. Cooley , et al. (104 additional authors not shown)

Abstract: Recent experiments searching for sub-GeV/$c^2$ dark matter have observed event excesses close to their respective energy thresholds. Although specific to the individual technologies, the measured excess event rates have been consistently reported at or below event energies of a few-hundred eV, or with charges of a few electron-hole pairs. In the present work, we operated a 1-gram silicon SuperCDMS… ▽ More Recent experiments searching for sub-GeV/$c^2$ dark matter have observed event excesses close to their respective energy thresholds. Although specific to the individual technologies, the measured excess event rates have been consistently reported at or below event energies of a few-hundred eV, or with charges of a few electron-hole pairs. In the present work, we operated a 1-gram silicon SuperCDMS-HVeV detector at three voltages across the crystal (0 V, 60 V and 100 V). The 0 V data show an excess of events in the tens of eV region. Despite this event excess, we demonstrate the ability to set a competitive exclusion limit on the spin-independent dark matter--nucleon elastic scattering cross section for dark matter masses of $\mathcal{O}(100)$ MeV/$c^2$, enabled by operation of the detector at 0 V potential and achievement of a very low $\mathcal{O}(10)$ eV threshold for nuclear recoils. Comparing the data acquired at 0 V, 60 V and 100 V potentials across the crystal, we investigated possible sources of the unexpected events observed at low energy. The data indicate that the dominant contribution to the excess is consistent with a hypothesized luminescence from the printed circuit boards used in the detector holder. △ Less

Submitted 11 October, 2022; v1 submitted 17 April, 2022; originally announced April 2022.

A Strategy for Low-Mass Dark Matter Searches with Cryogenic Detectors in the SuperCDMS SNOLAB Facility

Authors: SuperCDMS Collaboration, M. F. Albakry, I. Alkhatib, D. W. P. Amaral, T. Aralis, T. Aramaki, I. J. Arnquist, I. Ataee Langroudy, E. Azadbakht, S. Banik, C. Bathurst, D. A. Bauer, R. Bhattacharyya, P. L. Brink, R. Bunker, B. Cabrera, R. Calkins, R. A. Cameron, C. Cartaro, D. G. Cerdeno, Y. -Y. Chang, M. Chaudhuri, R. Chen, N. Chott, J. Cooley , et al. (103 additional authors not shown)

Abstract: The SuperCDMS Collaboration is currently building SuperCDMS SNOLAB, a dark matter search focused on nucleon-coupled dark matter in the 1-5 GeV/c$^2$ mass range. Looking to the future, the Collaboration has developed a set of experience-based upgrade scenarios, as well as novel directions, to extend the search for dark matter using the SuperCDMS technology in the SNOLAB facility. The experienced-ba… ▽ More The SuperCDMS Collaboration is currently building SuperCDMS SNOLAB, a dark matter search focused on nucleon-coupled dark matter in the 1-5 GeV/c$^2$ mass range. Looking to the future, the Collaboration has developed a set of experience-based upgrade scenarios, as well as novel directions, to extend the search for dark matter using the SuperCDMS technology in the SNOLAB facility. The experienced-based scenarios are forecasted to probe many square decades of unexplored dark matter parameter space below 5 GeV/c$^2$, covering over 6 decades in mass: 1-100 eV/c$^2$ for dark photons and axion-like particles, 1-100 MeV/c$^2$ for dark-photon-coupled light dark matter, and 0.05-5 GeV/c$^2$ for nucleon-coupled dark matter. They will reach the neutrino fog in the 0.5-5 GeV/c$^2$ mass range and test a variety of benchmark models and sharp targets. The novel directions involve greater departures from current SuperCDMS technology but promise even greater reach in the long run, and their development must begin now for them to be available in a timely fashion. The experienced-based upgrade scenarios rely mainly on dramatic improvements in detector performance based on demonstrated scaling laws and reasonable extrapolations of current performance. Importantly, these improvements in detector performance obviate significant reductions in background levels beyond current expectations for the SuperCDMS SNOLAB experiment. Given that the dominant limiting backgrounds for SuperCDMS SNOLAB are cosmogenically created radioisotopes in the detectors, likely amenable only to isotopic purification and an underground detector life-cycle from before crystal growth to detector testing, the potential cost and time savings are enormous and the necessary improvements much easier to prototype. △ Less

Submitted 1 April, 2023; v1 submitted 16 March, 2022; originally announced March 2022.

Comments: contribution to Snowmass 2021; v2 updated (assorted corrections and improvements to forecasts) October 2022; v3 updated (corrected SuperCDMS SNOLAB sensitivity curves in upgrade forecast plots in body of text) April 2023

Ionization yield measurement in a germanium CDMSlite detector using photo-neutron sources

Authors: SuperCDMS Collaboration, M. F. Albakry, I. Alkhatib, D. W. P. Amaral, T. Aralis, T. Aramaki, I. J. Arnquist, I. Ataee Langroudy, E. Azadbakht, S. Banik, C. Bathurst, D. A. Bauer, L. V. S. Bezerra, R. Bhattacharyya, M. A. Bowles, P. L. Brink, R. Bunker, B. Cabrera, R. Calkins, R. A. Cameron, C. Cartaro, D. G. Cerdeño, Y. -Y. Chang, M. Chaudhuri, R. Chen , et al. (104 additional authors not shown)

Abstract: Two photo-neutron sources, $^{88}$Y$^{9}$Be and $^{124}$Sb$^{9}$Be, have been used to investigate the ionization yield of nuclear recoils in the CDMSlite germanium detectors by the SuperCDMS collaboration. This work evaluates the yield for nuclear recoil energies between 1 keV and 7 keV at a temperature of $\sim$ 50 mK. We use a Geant4 simulation to model the neutron spectrum assuming a charge yie… ▽ More Two photo-neutron sources, $^{88}$Y$^{9}$Be and $^{124}$Sb$^{9}$Be, have been used to investigate the ionization yield of nuclear recoils in the CDMSlite germanium detectors by the SuperCDMS collaboration. This work evaluates the yield for nuclear recoil energies between 1 keV and 7 keV at a temperature of $\sim$ 50 mK. We use a Geant4 simulation to model the neutron spectrum assuming a charge yield model that is a generalization of the standard Lindhard model and consists of two energy dependent parameters. We perform a likelihood analysis using the simulated neutron spectrum, modeled background, and experimental data to obtain the best fit values of the yield model. The ionization yield between recoil energies of 1 keV and 7 keV is shown to be significantly lower than predicted by the standard Lindhard model for germanium. There is a general lack of agreement among different experiments using a variety of techniques studying the low-energy range of the nuclear recoil yield, which is most critical for interpretation of direct dark matter searches. This suggests complexity in the physical process that many direct detection experiments use to model their primary signal detection mechanism and highlights the need for further studies to clarify underlying systematic effects that have not been well understood up to this point. △ Less

Submitted 27 June, 2022; v1 submitted 14 February, 2022; originally announced February 2022.

Journal ref: Phys. Rev. D 105, 122002 (2022)

Observation of Gigahertz Topological Valley Hall Effect in Nanoelectromechanical Phononic Crystals

Authors: Qicheng Zhang, Daehun Lee, Lu Zheng, Xuejian Ma, Shawn I. Meyer, Li He, Han Ye, Ze Gong, Bo Zhen, Keji Lai, A. T. Charlie Johnson

Abstract: Topological phononics offers numerous opportunities in manipulating elastic waves that can propagate in solids without being backscattered. Due to the lack of nanoscale imaging tools that aid the system design, however, acoustic topological metamaterials have been mostly demonstrated in macroscale systems operating at low (kilohertz to megahertz) frequencies. Here, we report the realization of gig… ▽ More Topological phononics offers numerous opportunities in manipulating elastic waves that can propagate in solids without being backscattered. Due to the lack of nanoscale imaging tools that aid the system design, however, acoustic topological metamaterials have been mostly demonstrated in macroscale systems operating at low (kilohertz to megahertz) frequencies. Here, we report the realization of gigahertz topological valley Hall effect in nanoelectromechanical AlN membranes. Propagation of elastic wave through phononic crystals is directly visualized by microwave microscopy with unprecedented sensitivity and spatial resolution. The valley Hall edge states, protected by band topology, are vividly seen in both real- and momentum-space. The robust valley-polarized transport is evident from the wave transmission across local disorder and around sharp corners, as well as the power distribution into multiple edge channels. Our work paves the way to exploit topological physics in integrated acousto-electronic systems for classical and quantum information processing in the microwave regime. △ Less

Submitted 17 March, 2022; v1 submitted 4 February, 2022; originally announced February 2022.

Comments: 17 pages, 5 figures

Journal ref: Nature Electronics 5 (3), 157-163, 2022

On-demand storage of photonic qubits at telecom wavelengths

Authors: Duan-Cheng Liu, Pei-Yun Li, Tian-Xiang Zhu, Liang Zheng, Jian-Yin Huang, Zong-Quan Zhou, Chuan-Feng Li, Guang-Can Guo

Abstract: Quantum memories at telecom wavelengths are crucial for the construction of large-scale quantum networks based on existing fiber networks. On-demand storage of telecom photonic qubits is a fundamental request for such networking applications but yet to be demonstrated. Here we demonstrate the storage and on-demand retrieval of telecom photonic qubits using a laser-written waveguide fabricated in a… ▽ More Quantum memories at telecom wavelengths are crucial for the construction of large-scale quantum networks based on existing fiber networks. On-demand storage of telecom photonic qubits is a fundamental request for such networking applications but yet to be demonstrated. Here we demonstrate the storage and on-demand retrieval of telecom photonic qubits using a laser-written waveguide fabricated in an $^{167}$Er$^{3+}$:Y$_2$SiO$_5$ crystal. Both ends of the waveguide memory are directly connected with fiber arrays with a fiber-to-fiber efficiency of 51%. Storage fidelity of 98.3(1)% can be obtained for time-bin qubits encoded with single-photon-level coherent pulses, which is far beyond the maximal fidelity that can be achieved with a classical measure and prepare strategy. This device features high reliability, easy scalability and can be directly integrated into fiber networks, which could play an essential role in fiber-based quantum networks. △ Less

Submitted 16 November, 2022; v1 submitted 10 January, 2022; originally announced January 2022.

Comments: 13 pages, 10 figures

Journal ref: Phys. Rev. Lett. 129, 210501 (2022)

Spin wave propagation in uniform waveguide: effects, modulation and its application

Authors: Lei Zheng, Lichuan Jin, Tianlong Wen, Yulong Liao, Xiaoli Tang, Huaiwu Zhang, Zhiyong Zhong

Abstract: With the advent of the post-Moore era, researches on beyond-Complementary Metal Oxide Semiconductor (CMOS) approaches have been attracted more and more attention. Magnonics, or spin wave is one of the most promising technology beyond CMOS, which magnons-quanta for spin waves-process the information analogous to electronic charges in electronics. Information transmission by spin waves, which uses t… ▽ More With the advent of the post-Moore era, researches on beyond-Complementary Metal Oxide Semiconductor (CMOS) approaches have been attracted more and more attention. Magnonics, or spin wave is one of the most promising technology beyond CMOS, which magnons-quanta for spin waves-process the information analogous to electronic charges in electronics. Information transmission by spin waves, which uses the frequency, amplitude and (or) phase to encode information, has a great many of advantages such as extremely low energy loss and wide-band frequency. Moreover, using the nonlinear characteristics of spin waves for information transmission can increase the extra degree of freedom of information. This review provides a tutorial overview over the effects of spin wave propagation and recent research progress in uniform spin wave waveguide. The propagation characteristics of spin waves in uniform waveguides and some special propagation phenomena such as spin wave beam splitting and self-focusing are described by combining experimental phenomena and theoretical formulas. Furthermore, we summarize methods for modulating propagation of spin wave in uniform waveguide, and comment on the advantages and limitations of these methods. The review may promote the development of information transmission technology based on spin waves. △ Less

Submitted 27 September, 2021; originally announced September 2021.

Effect of density control in partially observable asymmetric-exit evacuation under guidance: Strategic suggestion under time delay

Authors: Fengqiang Gao, Yuyue Yan, Zhihao Chen, Linxiao Zheng, Huan Ren

Abstract: To enhance the evacuation efficiency in partially observable asymmetric-exit evacuation under guidance, a general framework of the dynamic guiding assistant system is presented to investigate the effect of density control. In this framework, several evacuation assistants are established to observe the partial information of pedestrians' location and adjust the guiding signals of the dynamic guidin… ▽ More To enhance the evacuation efficiency in partially observable asymmetric-exit evacuation under guidance, a general framework of the dynamic guiding assistant system is presented to investigate the effect of density control. In this framework, several evacuation assistants are established to observe the partial information of pedestrians' location and adjust the guiding signals of the dynamic guiding assistant systems. A simple on-off-based density control algorithm is proposed for the evacuation assistants according to the delayed data of the observed information (i.e., pedestrian densities in the observed regions near the corresponding exits). This paper provides strategic suggestions on how to set the observed region and the target density by involving a force-driven cellular automaton model. It is observed that the proposed density control algorithm can control (positively affect) the global distribution of the pedestrians' locations and suppress arching phenomena in the evacuation process even using the observed partial information under time delays. By imposing a moderate target density, the dynamic guiding assistant system also suppresses the triggers of collisions around the exits and avoids inefficiently separating the pedestrians. To enhance evacuation efficiency, we reveal an interesting fact without loss of generality that we only need to observe the pedestrians' location from a small region near the exit instead of a large region when the time delay of the observed information is slight enough. Our numerical findings are expected to provide new insights into designing computer-aided guiding strategies in real evacuations. △ Less

Submitted 13 November, 2021; v1 submitted 21 July, 2021; originally announced July 2021.

Comments: 15 pages, 11 figures

MSC Class: 91C20; 91-10 ACM Class: I.6.6; J.4

Nonreciprocal high-order sidebands induced by magnon Kerr nonlinearity

Authors: Mei Wang, Cui Kong, Zhao-Yu Sun, Duo Zhang, Yu-Ying Wu, Li-Li Zheng

Abstract: We propose an effective approach for creating robust nonreciprocity of high-order sidebands, including the first-, second- and third-order sidebands, at microwave frequencies. This approach relies on magnon Kerr nonlinearity in a cavity magnonics system composed of two microwave cavities and one yttrium iron garnet (YIG) sphere. By manipulating the driving power applied on YIG and the frequency de… ▽ More We propose an effective approach for creating robust nonreciprocity of high-order sidebands, including the first-, second- and third-order sidebands, at microwave frequencies. This approach relies on magnon Kerr nonlinearity in a cavity magnonics system composed of two microwave cavities and one yttrium iron garnet (YIG) sphere. By manipulating the driving power applied on YIG and the frequency detuning between the magnon mode in YIG and the driving field, the effective Kerr nonlinearity can be strengthened, thereby inducing strong transmission non-reciprocity. More interestingly, we find the higher the sideband order, the stronger the transmission nonreciprocity marked by the higher isolation ratio in the optimal detuning regime. Such a series of equally-spaced high-order sidebands have potential applications in frequency comb-like precision measurement, besides structuring high-performance on-chip nonreciprocal devices. △ Less

Submitted 14 June, 2021; originally announced June 2021.

Eliminating uncertainty of thermal emittance measurement in solenoid scans due to rf and solenoid fields overlap

Authors: Lianmin Zheng, Yingchao Du, Pengwei Huang

Abstract: The solenoid scan is one of the most common methods for the in-situ measurement of the thermal emittance of a photocathode in an rf photoinjector. The fringe field of the solenoid overlaps with the gun rf field in quite a number of photoinjectors, which makes accurate knowledge of the transfer matrix challenging, thus increases the measurement uncertainty of the thermal emittance. This paper summa… ▽ More The solenoid scan is one of the most common methods for the in-situ measurement of the thermal emittance of a photocathode in an rf photoinjector. The fringe field of the solenoid overlaps with the gun rf field in quite a number of photoinjectors, which makes accurate knowledge of the transfer matrix challenging, thus increases the measurement uncertainty of the thermal emittance. This paper summarizes two methods that have been used to solve the overlap issue and explains their deficiencies. Furthermore, we provide a new method to eliminate the measurement error due to the overlap issue in solenoid scans. The new method is systematically demonstrated using theoretical derivations, beam dynamics simulations, and experimental data based on the photoinjector configurations from three different groups, proving that the measurement error with the new method is very small and can be ignored in most of the photoinjector configurations. △ Less

Submitted 7 June, 2021; v1 submitted 4 June, 2021; originally announced June 2021.