Machine learning has revolutionized many fields,including materials science.However,predicting the properties of crystalline materials using machine learning faces challenges in input encoding,output versatility,and i...Machine learning has revolutionized many fields,including materials science.However,predicting the properties of crystalline materials using machine learning faces challenges in input encoding,output versatility,and interpretability.We introduce Crystal BERT,an adaptable transformer-based framework integrating space group,elemental,and unit cell information.This novel structure can seamlessly combine diverse features and accurately predict various physical properties,including topological properties,superconducting transition temperatures,dielectric constants,and more.Crystal BERT provides insightful interpretations of features influencing target properties.Our results indicate that space group and elemental information are crucial for predicting topological and superconducting properties,underscoring their intricate nature.By incorporating these features,we achieve91%accuracy in topological classification,surpassing prior studies and identifying previously misclassified materials.This research demonstrates that integrating diverse material information enhances the prediction of complex material properties,paving the way for more accurate and interpretable machine learning models in materials science.展开更多
One important issue in current condensed matter physics is the search of quantum spin liquid(QSL),an exotic magnetic state with strongly-fluctuating and highly-entangled spins down to zero temperature without static o...One important issue in current condensed matter physics is the search of quantum spin liquid(QSL),an exotic magnetic state with strongly-fluctuating and highly-entangled spins down to zero temperature without static order.However,there is no consensus on the existence of a QSL state in any real material so far,due to inevitable disorder and intricate competing exchange interactions on frustrated spin lattices.Here we report systematic heat transport measurements on a honeycomb-lattice compound BaCo_(2)(AsO_(4))_(2),which manifests magnetic order in zero field.In a narrow in-plane field range after the magnetic order is nearly suppressed,in both perpendicular and parallel to the zigzag direction,a finite residual linear term of thermal conductivity is clearly observed,which is attributed to mobile fermionic excitations.In addition,the spin-phonon scattering rate exhibits a T-linear behavior when the order disappears.These observations suggest a partial QSL state with gapless spinon excitations in BaCo_(2)(AsO_(4))_(2),that emerges when a portion of the spins remains ordered,and vanishes as the spins become progressively polarized.展开更多
Recently,charged solitons have been found in a two-dimensional CoCl_(2)/HOPG system,whose microscopic nature remains to be elusive.In this work,we investigate the charged solitons in monolayer CoCl_(2) using scanning ...Recently,charged solitons have been found in a two-dimensional CoCl_(2)/HOPG system,whose microscopic nature remains to be elusive.In this work,we investigate the charged solitons in monolayer CoCl_(2) using scanning tunneling microscopy(STM)and atomic force microscopy(AFM).Moreover,we study the electrical properties of the charged solitons at zero electric field by measuring local contact potential difference(LCPD)via Kelvin probe force microscopy(KPFM)using the Δf(V)method.The compensation voltage corresponding to the vertex of the parabola is obtained by fitting the quadratic relationship between Δf and sample bias.The results show that,without an external electric field,the solitons behave as negatively charged entities.Meanwhile,the LCPD mapping characterizes the spatial distribution of the potential at the charged solitons,which agrees well with those obtained from STM band bending measurements.展开更多
We demonstrate a reinforcement learning(RL)-based control framework for optimizing evaporative cooling in the preparation of strongly interacting degenerate Fermi gases of 6Li.Using a Soft Actor-Critic(SAC)algorithm,t...We demonstrate a reinforcement learning(RL)-based control framework for optimizing evaporative cooling in the preparation of strongly interacting degenerate Fermi gases of 6Li.Using a Soft Actor-Critic(SAC)algorithm,the system autonomously explores a high-dimensional parameter space to learn optimal cooling trajectories.Compared to conventional exponential ramps,our method achieves up to 130%improvement in atomic density within 0.5 second,revealing non-trivial control strategies that balance fast evaporation and thermalization.While our current optimization focuses on the evaporation stage,future integration of other cooling stages,such as gray molasses cooling,could further extend RL to the full preparation pipeline.Our result highlights the promise of RL as a general tool for closed-loop quantum control and automated calibration in complex atomic physics experiments.展开更多
Photonic neural networks(PNNs)of sufficiently large physical dimensions and high operation accuracies are envisaged as ideal candidates for breaking the major bottlenecks in the current artificial intelligence archite...Photonic neural networks(PNNs)of sufficiently large physical dimensions and high operation accuracies are envisaged as ideal candidates for breaking the major bottlenecks in the current artificial intelligence architectures in terms of latency,energy efficiency,and computational power.To achieve this vision,it is of vital importance to scale up the PNNs while simultaneously reducing the high demand on the dimensions required by them.The underlying cause of this strategy is the enormous gap between the scales of photonic and electronic integrated circuits.Here,we demonstrate monolithically integrated optical convolutional processors on thin film lithium niobate(TFLN)that harness inherent parallelism in photonics to enable large-scale programmable convolution kernels and,in turn,greatly reduce the dimensions required by subsequent fully connected layers.Experimental validation achieves high classification accuracies of 96%(86%)on the MNIST(Fashion-MNIST)dataset and 84.6%on the AG News dataset while dramatically reducing the required subsequent fully connected layer dimensions to 196×10(from 784×10)and 175×4(from 800×4),respectively.Furthermore,our devices can be driven by commercial field-programmable gate array systems;a unique advantage in addition to their scalable channel number and kernel size.Our architecture provides a solution to build practical machine learning photonic devices.展开更多
Optical two-way time-frequency transfer(O-TWTFT),utilizing optical frequency comb carriers and linear optical sampling,effectively enables space-to-ground optical frequency standard comparisons.Previously reported det...Optical two-way time-frequency transfer(O-TWTFT),utilizing optical frequency comb carriers and linear optical sampling,effectively enables space-to-ground optical frequency standard comparisons.Previously reported detection sensitivities of O-TWTFTs were typically in the nanoWatt level,necessitating high-power optical frequency combs to compensate for significant losses in high-orbit satellite-to-ground passes.Such hardware-based solutions,while effective,tend to be costly.This paper presents a novel data post-processing algorithm to enhance sensitivity.Unlike previous timing methods,which depend solely on optical phase data and discard intensity information—resulting in elevated errors,especially under low-reception power,our approach employs complex least squares(CLS)estimation in the complex frequency domain.By preserving all intermediate data and avoiding noise from phase unwrapping,it achieves superior sensitivity and accuracy.Experiments over a 113-kilometer free-space link validate the algorithm's robustness,delivering a detection sensitivity of0.1 nanoWatts—over tenfold better than prior techniques—despite a 100-decibel link loss,comparable to Earth-Moon optical links.展开更多
We here report a high system detection efficiency(SDE)superconducting single-photon detector(SSPD)at 2μm wavelength.The device integrates a SiO_(2)/Ta_(2)O_(5)distributed Bragg reflector(DBR)and a sandwich-structured...We here report a high system detection efficiency(SDE)superconducting single-photon detector(SSPD)at 2μm wavelength.The device integrates a SiO_(2)/Ta_(2)O_(5)distributed Bragg reflector(DBR)and a sandwich-structured double-layer NbN nanowire to enhance the optical absorption efficiency.A cold development technique is implemented to optimize the superconducting nanowires with sub-40-nm linewidths,thus enhancing the intrinsic detection efficiency(IDE).The fabricated SSPD shows an SDE exceeding 90% at 2μm wavelength.Moreover,the detector allows an operational working temperature of 2.2 K provided by a compact GM cryo-cooler.This detector delivers excellent performance at the 2μm wavelength,and its optimized structural design implies promising potential for extending detection toward longer infrared bands.It thus holds value for advancing high-sensitivity quantum technologies,mid-infrared optical communications,and dark matter detection research.展开更多
For an atomic gravimeter,the measured value of the Earth’s gravity acceleration g is the projection of the local gravity on the direction of Raman laser beams.To accurately measure the g,the Raman laser beams should ...For an atomic gravimeter,the measured value of the Earth’s gravity acceleration g is the projection of the local gravity on the direction of Raman laser beams.To accurately measure the g,the Raman laser beams should be parallel to the g direction.We analyze the tilt effect of the Raman beams on g measurement and present a general method for the tilt adjustment.The systematic error caused by the tilt angle is evaluated as 0(+0,0.8)µGal(1µGal=10 nm/s^2)and the drift is also compensated in real time.Our method is especially suitable for the portable atomic gravimeter which focuses on the mobility and field applications.展开更多
Temperature is a fundamental thermodynamic variable for matter.Physical observables are often found to either increase or decrease with it,or show a non-monotonic dependence with peaks signaling underlying phase trans...Temperature is a fundamental thermodynamic variable for matter.Physical observables are often found to either increase or decrease with it,or show a non-monotonic dependence with peaks signaling underlying phase transitions or anomalies.Statistical Held theory has established connection between temperature and time:a quantum ensemble with inverse temperatureβis formally equivalent to a dynamic system evolving along an imaginary time from 0 to iβin the space one dimension higher.Here we report that a gas of hard-core bosons interacting with a thermal bath manifests an unexpected temperature-periodic oscillation of its macroscopic observables,arising from the microscopic origin of space-time locked translational symmetry breaking and crystalline ordering.Such a temperature crystal,supported by quantum Monte Carlo simulation,generalizes the concept of purely spatial density-wave order to the imaginary time axis for Euclidean action.展开更多
The physical concept of synthetic dimensions has recently been introduced into optics.The fundamental physics and applications are not yet fully understood,and this report explores an approach to optical neural networ...The physical concept of synthetic dimensions has recently been introduced into optics.The fundamental physics and applications are not yet fully understood,and this report explores an approach to optical neural networks using synthetic dimension in time domain,by theoretically proposing to utilize a single resonator network,where the arrival times of optical pulses are interconnected to construct a temporal synthetic dimension.The set of pulses in each roundtrip therefore provides the sites in each layer in the optical neural network,and can be linearly transformed with splitters and delay lines,including the phase modulators,when pulses circulate inside the network.Such linear transformation can be arbitrarily controlled by applied modulation phases,which serve as the building block of the neural network together with a nonlinear component for pulses.We validate the functionality of the proposed optical neural network for the deep learning purpose with examples handwritten digit recognition and optical pulse train distribution classification problems.This proof of principle computational work explores the new concept of developing a photonics-based machine learning in a single ring network using synthetic dimensions,which allows flexibility and easiness of reconfiguration with complex functionality in achieving desired optical tasks.展开更多
V-based kagome superconductors AV_(3)Sb_(5)(A=K,Rb,and Cs)host a charge density wave(CDW)and a topological nontrivial band structure,thereby providing a great platform to study the interplay of superconductivity(SC),C...V-based kagome superconductors AV_(3)Sb_(5)(A=K,Rb,and Cs)host a charge density wave(CDW)and a topological nontrivial band structure,thereby providing a great platform to study the interplay of superconductivity(SC),CDW,frustration,and topology.Here,we report ultralow-temperature thermal conductivity measurements of CsV_(3)Sb_(5 ) and Ta-doped Cs((V_(0.86)Ta_(0.14)))_(3)Sb_(5) and scanning tunneling microscopy(STM)measurements of CsV_(3)Sb_(5 ).The finite residual linear term of thermal conductivity at zero magnetic field suggests the existence of a residual density of states(DOS)in the superconducting state of CsV_(3)Sb_(5 ).This is supported by the observation of non-zero conductance at zero bias in STM spectrum at an electronic temperature of 90 mK.However,in Cs(V_(0.86)Ta_(0.14))_(3)Sb_(5),which does not have CDW order,there is no evidence for the residual DOS.These results show the importance of CDW order for the residual DOS,and that a nodal s-wave gap or residual Fermi arc may be the origin of the residual DOS in such an unusual multiband kagome superconductor,CsV_(3)Sb_(5 ).展开更多
The ability to control nonclassical light emission from a single quantum emitter by an integrated cavity may unleash new perspectives for integrated photonic quantum applications.However,coupling a single quantum emit...The ability to control nonclassical light emission from a single quantum emitter by an integrated cavity may unleash new perspectives for integrated photonic quantum applications.However,coupling a single quantum emitter to cavity within photonic circuitry towards creation of the Purcell-enhanced single-photon emission is elusive due to the complexity of integrating active devices in low-loss photonic circuits.Here we demonstrate a hybrid micro-ring resonator(HMRR)coupled with self-assembled quantum dots(QDs)for cavity-enhanced deterministic single-photon emission.The HMRR cavity supports whispering-gallery modes with quality factors up to 7.8×103.By further introducing a micro-heater,we show that the photon emission of QDs can be locally and dynamically tuned over one free spectral ranges of the HMRR(~4 nm).This allows precise tuning of individual QDs in resonance with the cavity modes,thereby enhancing single-photon emission with a Purcell factor of about 4.9.Our results on the hybrid integrated cavities coupled with two-level quantum emitters emerge as promising devices for chip-based scalable photonic quantum applications.展开更多
In this work,Ga-doped Ce RhIn_(5) single crystals are grown by In/Ga flux method.Single-crystal X-ray diffraction,magnetic susceptibility,specific heat,and neutron diffraction measurements are utilized to characterize...In this work,Ga-doped Ce RhIn_(5) single crystals are grown by In/Ga flux method.Single-crystal X-ray diffraction,magnetic susceptibility,specific heat,and neutron diffraction measurements are utilized to characterize the sample quality and the antiferromagnetic transition temperature T_(N).By substituting In with Ga,T_(N) is slightly decreased,but the antiferromagnetic transition peaks in magnetic susceptibility and specific heat measurements are obviously broadened by external field along c-axis.By comparing with Zn-doped Ce RhIn_(5),it can be concluded that T_(N) is dominated by electron density,and the stiffness of antiferromagnetic transition is obviously reduced by Ga substitution.The substitution effects of Ga are possibly caused by forming heterogeneous local structures,which avoids quantum critical point,superconductivity,and non-Fermi liquid states.Investigations on Gadoped Ce RhIn_(5) help to comprehend the chemical substitution effects in Ce RhIn_(5),and the interaction between heterogeneous structure and long-range antiferromagnetic states.展开更多
Reliable detection of weak phase signals under significant channel loss and complex noise environments is a crucial step for practical applications of optical integrated communication and sensing systems. In this lett...Reliable detection of weak phase signals under significant channel loss and complex noise environments is a crucial step for practical applications of optical integrated communication and sensing systems. In this letter, we propose and experimentally demonstrate an enhanced long-distance weak signal transmission method assisted by weak measurement. Performing heterodyne detection and light intensity compensation on two nearly symmetric post-selected paths, the method enables real-time estimation of a time-varying phase while maintaining robustness against technical noises proportional to light intensity or photon number, detector common-mode noise, and significant attenuation over long-distance transmission. Experimental results indicate a potential phase sensitivity at the level of 10-8rad even with a signal light intensity attenuation of 48.1 d B. Potentially, combining the adaptive adjustment strategy, the method may provide a viable solution in remote weak signal detection and extraction,thereby contributing to optical integrated communication and sensing.展开更多
LiV_(2)O_(4)is a spinel-structured compound that stands out as the first known 3d-electron system exhibiting typical heavy fermion behavior.A central question is how such strong mass renormalization emerges in the abs...LiV_(2)O_(4)is a spinel-structured compound that stands out as the first known 3d-electron system exhibiting typical heavy fermion behavior.A central question is how such strong mass renormalization emerges in the absence of f-electrons.In this work,we investigate the three-dimensional electronic structure of LiV_(2)O_(4)thin films using angle-resolved photoemission spectroscopy.We identify that an electron-like flat band is derived from a_(1g)orbitals,along with a highly dispersive e′_(g)band strongly coupled with phonons.The overall agreement with dynamical mean-field theory calculations highlights the essential role of inter-orbital Hund’s coupling in reducing the a_(1g)bandwidth to 25 meV,approaching a Mott state.Notably,we find that heavy-fermion behavior arises from additional renormalization at the a_(1g)band near the Fermi level,likely driven by many-body interactions at energy scales down to a few meV and potentially linked to geometric frustration inherent to the spinel lattice.These results provide crucial insights into the origin of the heavy fermion behavior in 3d-electron systems.展开更多
We present a compact optical delay line(ODL)with wide-range continuous tunability on thin-film lithium niobate platform.The proposed device integrates an unbalanced Mach-Zehnder interferometer(MZI)architecture with du...We present a compact optical delay line(ODL)with wide-range continuous tunability on thin-film lithium niobate platform.The proposed device integrates an unbalanced Mach-Zehnder interferometer(MZI)architecture with dual tunable couplers,where each coupler comprises two 2×2 multimode interferometers and a MZI phase-tuning section.Experimental results demonstrate continuous delay tuning from 0 to 293 ps through synchronized control of coupling coefficients,corresponding to a 4 cm path difference between interferometer arms.The measured delay range exhibits excellent agreement with theoretical predictions derived from ODL waveguide parameters.This result addresses critical challenges in integrated photonic systems that require precise temporal control,particularly for applications in optical communications and quantum information processing,where a wide tuning range is paramount.展开更多
The crossover between short-range and long-range(LR)universal behaviors remains a central theme in the physics of LR interacting systems.The competition between LR coupling and the Berezinskii-Kosterlitz-Thouless mech...The crossover between short-range and long-range(LR)universal behaviors remains a central theme in the physics of LR interacting systems.The competition between LR coupling and the Berezinskii-Kosterlitz-Thouless mechanism makes the problem more subtle and less understood in the two-dimensional(2D)XY model,a cornerstone for investigating low-dimensional phenomena and their implications in quantum computation.We study the 2D XY model with algebraically decaying interaction~1/r^(2+σ).Utilizing an advanced update strategy,we conduct LR Monte Carlo simulations of the model up to a linear size of L=8192.Our results demonstrate continuous phase transitions into a ferromagnetic phase forσ<2,which exhibit the simultaneous emergence of a long-ranged order and a power-law decaying correlation function due to the Goldstone mode.Furthermore,we fnd logarithmic scaling behaviors in the low-temperature phase atσ=2.The observed scaling behaviors in the low-temperature phase forσ≤2 agree with our theoretical analysis.Our fndings request further theoretical understanding and can be of practical application in cutting-edge experiments like Rydberg atom arrays.展开更多
Optical phase transfer via fiber optics is the most effective method for optical frequency standard comparison on the scale below thousands of kilometers.However,the monotonic phase discrimination range of conventiona...Optical phase transfer via fiber optics is the most effective method for optical frequency standard comparison on the scale below thousands of kilometers.However,the monotonic phase discrimination range of conventional optical phase-locked loops is limited,and link delays restrict the control bandwidth,which makes it a challenge to achieve a continuously reliable optical link.This paper presents an event-timing-based phase detection method that overcomes the monotonic phase discrimination range limitation of conventional phase-locked loops through dual-edge timestamp recording,achieving an optical phase measurement resolution on the order of 10 attoseconds.With such a technique,we established a 7-segment-cascaded optical link over 1402km of commercial fiber while sharing dense wavelength division multiplexing(DWDM)channels with live telecom traffic.The system maintained continuous operation for 11.7 days without phase cycle slips despite encountering 15 km aerial fiber noise up to 21000 rad^(2)·Hz^(−1)·km^(−1)at 1 Hz.Relative instabilities of the link are 3.7×10^(−15)at 1 s and 3.9×10^(−20)at 100000 s.展开更多
In antiferromagnets,dipolar coupling is often disregarded due to the cancellation of magnetic moments between the two sublattices,so that the spin-wave dispersion is predominantly determined by exchange interactions.H...In antiferromagnets,dipolar coupling is often disregarded due to the cancellation of magnetic moments between the two sublattices,so that the spin-wave dispersion is predominantly determined by exchange interactions.However,antiferromagnetic spin waves typically involve a slight misalignment of the magnetic moments on the sublattices,which gives rise to a small net magnetization enabling long-range dipolar coupling.In this paper,we investigate the role of dipolar coupling in spin-wave excitations and its influence on the resulting dispersion.Our findings show that:(i)when the Néel vector is perpendicular to the film plane or lies within the film plane and parallel to the wave vector,the dispersion branches can be divided into two groups:those unaffected by the dipolar field and those influenced by it.In these cases,the total magnetic moment remains linearly polarized,but the polarization directions differ between the two types of branches;(ii)when the Néel vector lies in the film plane and is perpendicular to the wave vector,the dipolar interactions affect both types of dispersion branches,leading to their hybridization.This hybridization alters the polarization of the magnetic moment,resulting in elliptical polarization.展开更多
Moirésystems have emerged as an ideal platform for exploring interaction effects and correlated states.However,most of the experimental systems are based on either triangular or honeycomb lattices.In this study,b...Moirésystems have emerged as an ideal platform for exploring interaction effects and correlated states.However,most of the experimental systems are based on either triangular or honeycomb lattices.In this study,based on the self-consistent Hartree–Fock calculation,we investigate the phase diagram of the kagomélattice in a recently discovered system with two degenerateΓvalley orbitals and strong spin–orbit coupling.By focusing on the filling factors of 1/2,1/3 and 2/3,we identify various symmetry-breaking states by adjusting the screening length and dielectric constant.At the half filling,we discover that the spin–orbit coupling induces Dzyaloshinskii–Moriya interaction and stabilizes a classical magnetic state with 120°ordering.Additionally,we observe a transition to a ferromagnetic state with out-of-plane ordering.In the case of 1/3 filling,the system is ferromagnetically ordered due to the lattice frustration.Furthermore,for 2/3 filling,the system exhibits a pinned droplet state and a 120°magnetic ordered state at weak and immediate coupling strengths,respectively.For the strong coupling case,when dealing with non-integer filling,the system is always charge ordered with sublattice polarization.Our study serves as a starting point for exploring the effects of correlation in moirékagomésystems.展开更多
基金supported by the Natural Science Foundation of China(Grant Nos.12350404 and 12174066)the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0302600)+2 种基金the Science and Technology Commission of Shanghai Municipality(Grant Nos.23JC1400600,24LZ1400100,and 2019SHZDZX01)sponsored by“Shuguang Program”supported by Shanghai Education Development FoundationShanghai Municipal Education Commission。
文摘Machine learning has revolutionized many fields,including materials science.However,predicting the properties of crystalline materials using machine learning faces challenges in input encoding,output versatility,and interpretability.We introduce Crystal BERT,an adaptable transformer-based framework integrating space group,elemental,and unit cell information.This novel structure can seamlessly combine diverse features and accurately predict various physical properties,including topological properties,superconducting transition temperatures,dielectric constants,and more.Crystal BERT provides insightful interpretations of features influencing target properties.Our results indicate that space group and elemental information are crucial for predicting topological and superconducting properties,underscoring their intricate nature.By incorporating these features,we achieve91%accuracy in topological classification,surpassing prior studies and identifying previously misclassified materials.This research demonstrates that integrating diverse material information enhances the prediction of complex material properties,paving the way for more accurate and interpretable machine learning models in materials science.
基金funded by the National Natural Science Foundations of China(Grant Nos.12034004 and 12174064)the Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01)+2 种基金the Innovation Program for Quantum Science and Technology(Grant No.2024ZD0300104)supported by U.S.DOE BES DE-SC0012311the Robert A.Welch Foundation under Grant No.C-1839,respectively(P.D.)。
文摘One important issue in current condensed matter physics is the search of quantum spin liquid(QSL),an exotic magnetic state with strongly-fluctuating and highly-entangled spins down to zero temperature without static order.However,there is no consensus on the existence of a QSL state in any real material so far,due to inevitable disorder and intricate competing exchange interactions on frustrated spin lattices.Here we report systematic heat transport measurements on a honeycomb-lattice compound BaCo_(2)(AsO_(4))_(2),which manifests magnetic order in zero field.In a narrow in-plane field range after the magnetic order is nearly suppressed,in both perpendicular and parallel to the zigzag direction,a finite residual linear term of thermal conductivity is clearly observed,which is attributed to mobile fermionic excitations.In addition,the spin-phonon scattering rate exhibits a T-linear behavior when the order disappears.These observations suggest a partial QSL state with gapless spinon excitations in BaCo_(2)(AsO_(4))_(2),that emerges when a portion of the spins remains ordered,and vanishes as the spins become progressively polarized.
基金supported by the National Key Research and Development Program of China(Grant Nos.2022YFA1403300 and 2019YFA0308404)the National Natural Science Foundation of China(Grant Nos.11427902,11991060,12074075,12474165,12274084,and 12241402)+5 种基金Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01)Shanghai Municipal Natural Science Foundation(Grant No.22ZR1407400)Innovation Program for Quantum Science and Technology(Grant No.2024ZD0300104)Innovation Program of Shanghai Municipal Education Commission(Grant No.2023ZKZD03)Science and Technology Commission of Shanghai Municipality(Grant No.20JC1415900)China Postdoctoral Science Foundation(Grant No.KLH1512149).
文摘Recently,charged solitons have been found in a two-dimensional CoCl_(2)/HOPG system,whose microscopic nature remains to be elusive.In this work,we investigate the charged solitons in monolayer CoCl_(2) using scanning tunneling microscopy(STM)and atomic force microscopy(AFM).Moreover,we study the electrical properties of the charged solitons at zero electric field by measuring local contact potential difference(LCPD)via Kelvin probe force microscopy(KPFM)using the Δf(V)method.The compensation voltage corresponding to the vertex of the parabola is obtained by fitting the quadratic relationship between Δf and sample bias.The results show that,without an external electric field,the solitons behave as negatively charged entities.Meanwhile,the LCPD mapping characterizes the spatial distribution of the potential at the charged solitons,which agrees well with those obtained from STM band bending measurements.
基金supported by the Innovation Program for Quantum Science and Technology of China(Grant No.2024ZD0300100)the National Basic Research Program of China(Grant No.2021YFA1400900)+1 种基金Shanghai Municipal Science and Technology(Grant Nos.25TQ003,2019SHZDZX01,and 24DP2600100)the National Natural Science Foundation of China(Grant No.12304555).
文摘We demonstrate a reinforcement learning(RL)-based control framework for optimizing evaporative cooling in the preparation of strongly interacting degenerate Fermi gases of 6Li.Using a Soft Actor-Critic(SAC)algorithm,the system autonomously explores a high-dimensional parameter space to learn optimal cooling trajectories.Compared to conventional exponential ramps,our method achieves up to 130%improvement in atomic density within 0.5 second,revealing non-trivial control strategies that balance fast evaporation and thermalization.While our current optimization focuses on the evaporation stage,future integration of other cooling stages,such as gray molasses cooling,could further extend RL to the full preparation pipeline.Our result highlights the promise of RL as a general tool for closed-loop quantum control and automated calibration in complex atomic physics experiments.
基金supported by the National Natural Science Foundation of China (Grant Nos.12192251,12334014,62335019,12134001,1230441812474378)+1 种基金the Quantum Science and Technology National Science and Technology Major Project(Grant No.2021ZD0301403)the Shanghai Municipal Science and Technology Major Project (Grant No.2019SHZDZX01)。
文摘Photonic neural networks(PNNs)of sufficiently large physical dimensions and high operation accuracies are envisaged as ideal candidates for breaking the major bottlenecks in the current artificial intelligence architectures in terms of latency,energy efficiency,and computational power.To achieve this vision,it is of vital importance to scale up the PNNs while simultaneously reducing the high demand on the dimensions required by them.The underlying cause of this strategy is the enormous gap between the scales of photonic and electronic integrated circuits.Here,we demonstrate monolithically integrated optical convolutional processors on thin film lithium niobate(TFLN)that harness inherent parallelism in photonics to enable large-scale programmable convolution kernels and,in turn,greatly reduce the dimensions required by subsequent fully connected layers.Experimental validation achieves high classification accuracies of 96%(86%)on the MNIST(Fashion-MNIST)dataset and 84.6%on the AG News dataset while dramatically reducing the required subsequent fully connected layer dimensions to 196×10(from 784×10)and 175×4(from 800×4),respectively.Furthermore,our devices can be driven by commercial field-programmable gate array systems;a unique advantage in addition to their scalable channel number and kernel size.Our architecture provides a solution to build practical machine learning photonic devices.
基金supported by the National Key Research and Development Programme of China(Grant Nos.2020YFC2200103 and 2020YFA0309800)the National Natural Science Foundation of China(Grant No.T2125010)+4 种基金Strategic Priority Research Programme of Chinese Academy of Sciences(Grant No.XDB35030000)Anhui Initiative in Quantum Information Technologies(Grant No.AHY010100)Key R&D Plan of Shandong Province(Grant No.2021ZDPT01)Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01)Innovation Programme for Quantum Science and Technology(Grant Nos.2021ZD0300100,2021ZD0300300,and2021ZD0300903)。
文摘Optical two-way time-frequency transfer(O-TWTFT),utilizing optical frequency comb carriers and linear optical sampling,effectively enables space-to-ground optical frequency standard comparisons.Previously reported detection sensitivities of O-TWTFTs were typically in the nanoWatt level,necessitating high-power optical frequency combs to compensate for significant losses in high-orbit satellite-to-ground passes.Such hardware-based solutions,while effective,tend to be costly.This paper presents a novel data post-processing algorithm to enhance sensitivity.Unlike previous timing methods,which depend solely on optical phase data and discard intensity information—resulting in elevated errors,especially under low-reception power,our approach employs complex least squares(CLS)estimation in the complex frequency domain.By preserving all intermediate data and avoiding noise from phase unwrapping,it achieves superior sensitivity and accuracy.Experiments over a 113-kilometer free-space link validate the algorithm's robustness,delivering a detection sensitivity of0.1 nanoWatts—over tenfold better than prior techniques—despite a 100-decibel link loss,comparable to Earth-Moon optical links.
基金supported by the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDA0520403)Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01))+1 种基金Innovation Program for Quantum Science and Technology(Grant No.2023ZD0300100)the National Natural Science Foundation of China(Grant Nos.U24A20320 and 62401554)。
文摘We here report a high system detection efficiency(SDE)superconducting single-photon detector(SSPD)at 2μm wavelength.The device integrates a SiO_(2)/Ta_(2)O_(5)distributed Bragg reflector(DBR)and a sandwich-structured double-layer NbN nanowire to enhance the optical absorption efficiency.A cold development technique is implemented to optimize the superconducting nanowires with sub-40-nm linewidths,thus enhancing the intrinsic detection efficiency(IDE).The fabricated SSPD shows an SDE exceeding 90% at 2μm wavelength.Moreover,the detector allows an operational working temperature of 2.2 K provided by a compact GM cryo-cooler.This detector delivers excellent performance at the 2μm wavelength,and its optimized structural design implies promising potential for extending detection toward longer infrared bands.It thus holds value for advancing high-sensitivity quantum technologies,mid-infrared optical communications,and dark matter detection research.
基金Project supported by the National Key R&D Program of China(Grant No.2016YFA0301601)the National Natural Science Foundation of China(Grant No.11674301)+1 种基金Anhui Initiative in Quantum Information Technologies,China(Grant No.AHY120000)Shanghai Municipal Science and Technology Major Project,China(Grant No.2019SHZDZX01).
文摘For an atomic gravimeter,the measured value of the Earth’s gravity acceleration g is the projection of the local gravity on the direction of Raman laser beams.To accurately measure the g,the Raman laser beams should be parallel to the g direction.We analyze the tilt effect of the Raman beams on g measurement and present a general method for the tilt adjustment.The systematic error caused by the tilt angle is evaluated as 0(+0,0.8)µGal(1µGal=10 nm/s^2)and the drift is also compensated in real time.Our method is especially suitable for the portable atomic gravimeter which focuses on the mobility and field applications.
基金National Key Research and Development Program of China(Grant No.2016YFA0302001)National Natural Science Foundation of China(Grant Nos.11674221 and 11745006)+5 种基金Shanghai Rising-Star ProgramEastern Scholar Professor of Distinguished Appointment Programthe AFOSR(Grant No.FA9550-16-1-0006)MURI-ARO(Grant No.W911NF-17-1-0323)through UC Santa Barbara,the NSF China Overseas Scholar Collaborative Program(Grant No.11429402)Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01)。
文摘Temperature is a fundamental thermodynamic variable for matter.Physical observables are often found to either increase or decrease with it,or show a non-monotonic dependence with peaks signaling underlying phase transitions or anomalies.Statistical Held theory has established connection between temperature and time:a quantum ensemble with inverse temperatureβis formally equivalent to a dynamic system evolving along an imaginary time from 0 to iβin the space one dimension higher.Here we report that a gas of hard-core bosons interacting with a thermal bath manifests an unexpected temperature-periodic oscillation of its macroscopic observables,arising from the microscopic origin of space-time locked translational symmetry breaking and crystalline ordering.Such a temperature crystal,supported by quantum Monte Carlo simulation,generalizes the concept of purely spatial density-wave order to the imaginary time axis for Euclidean action.
基金the National Natural Science Foundation of China(Grant Nos.12122407,11974245,and 12192252)the Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01-ZX06)+6 种基金partial funding from NSF(Grant Nos.DBI-1455671,ECCS-1509268,and CMMI-1826078)AFOSR(Grant Nos.FA9550-15-1-0517,FA9550-18-1-0141,FA9550-201-0366,and FA9550-20-1-0367)DOD Army Medical Research(Grant No.W81XWH2010777)NIH(Grant Nos.1R01GM127696-01 and 1R21GM142107-01)the Cancer Prevention and Research Institute of Texas(Grant No.RP180588)the sponsorship from Yangyang Development Fundthe support from the Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learning。
文摘The physical concept of synthetic dimensions has recently been introduced into optics.The fundamental physics and applications are not yet fully understood,and this report explores an approach to optical neural networks using synthetic dimension in time domain,by theoretically proposing to utilize a single resonator network,where the arrival times of optical pulses are interconnected to construct a temporal synthetic dimension.The set of pulses in each roundtrip therefore provides the sites in each layer in the optical neural network,and can be linearly transformed with splitters and delay lines,including the phase modulators,when pulses circulate inside the network.Such linear transformation can be arbitrarily controlled by applied modulation phases,which serve as the building block of the neural network together with a nonlinear component for pulses.We validate the functionality of the proposed optical neural network for the deep learning purpose with examples handwritten digit recognition and optical pulse train distribution classification problems.This proof of principle computational work explores the new concept of developing a photonics-based machine learning in a single ring network using synthetic dimensions,which allows flexibility and easiness of reconfiguration with complex functionality in achieving desired optical tasks.
文摘V-based kagome superconductors AV_(3)Sb_(5)(A=K,Rb,and Cs)host a charge density wave(CDW)and a topological nontrivial band structure,thereby providing a great platform to study the interplay of superconductivity(SC),CDW,frustration,and topology.Here,we report ultralow-temperature thermal conductivity measurements of CsV_(3)Sb_(5 ) and Ta-doped Cs((V_(0.86)Ta_(0.14)))_(3)Sb_(5) and scanning tunneling microscopy(STM)measurements of CsV_(3)Sb_(5 ).The finite residual linear term of thermal conductivity at zero magnetic field suggests the existence of a residual density of states(DOS)in the superconducting state of CsV_(3)Sb_(5 ).This is supported by the observation of non-zero conductance at zero bias in STM spectrum at an electronic temperature of 90 mK.However,in Cs(V_(0.86)Ta_(0.14))_(3)Sb_(5),which does not have CDW order,there is no evidence for the residual DOS.These results show the importance of CDW order for the residual DOS,and that a nodal s-wave gap or residual Fermi arc may be the origin of the residual DOS in such an unusual multiband kagome superconductor,CsV_(3)Sb_(5 ).
基金support from National Key R&D Program of China(2022YFA1404604)Chinese Academy of Sciences Project for Young Scientists in Basic Research(No.YSBR-112),Science and Technology Commission of Shanghai Municipality(16ZR1442600,20JC1416200)+6 种基金National Natural Science Foundation of China(Nos.12074400,U1732268,62293521,61874128,61851406,11774326 and 11705262)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB0670303)Shanghai Science and Technology Innovation Action Plan Program(20JC1416200,22JC1403300)Frontier Science Key Program of Chinese Academy of Sciences(No.QYZDY-SSW-JSC032),Innovation Program for Quantum Science and Technology(No.2021ZD0300204)Shanghai Municipal Science and Technology Major Project(No.2019SHZDZX01)Autonomous deployment project of State Key Laboratory of Materials for Integrated Circuits(No.SKLJCZ2024-B03)State Key Laboratory of Advanced Optical Communication Systems and Networks(No.2024GZKF11).
文摘The ability to control nonclassical light emission from a single quantum emitter by an integrated cavity may unleash new perspectives for integrated photonic quantum applications.However,coupling a single quantum emitter to cavity within photonic circuitry towards creation of the Purcell-enhanced single-photon emission is elusive due to the complexity of integrating active devices in low-loss photonic circuits.Here we demonstrate a hybrid micro-ring resonator(HMRR)coupled with self-assembled quantum dots(QDs)for cavity-enhanced deterministic single-photon emission.The HMRR cavity supports whispering-gallery modes with quality factors up to 7.8×103.By further introducing a micro-heater,we show that the photon emission of QDs can be locally and dynamically tuned over one free spectral ranges of the HMRR(~4 nm).This allows precise tuning of individual QDs in resonance with the cavity modes,thereby enhancing single-photon emission with a Purcell factor of about 4.9.Our results on the hybrid integrated cavities coupled with two-level quantum emitters emerge as promising devices for chip-based scalable photonic quantum applications.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFA1402203)the National Natural Science Foundations of China(Grant Nos.12174065 and 12104424)the Shanghai Municipal Science and Technology(Grant No.2019SHZDZX01)。
文摘In this work,Ga-doped Ce RhIn_(5) single crystals are grown by In/Ga flux method.Single-crystal X-ray diffraction,magnetic susceptibility,specific heat,and neutron diffraction measurements are utilized to characterize the sample quality and the antiferromagnetic transition temperature T_(N).By substituting In with Ga,T_(N) is slightly decreased,but the antiferromagnetic transition peaks in magnetic susceptibility and specific heat measurements are obviously broadened by external field along c-axis.By comparing with Zn-doped Ce RhIn_(5),it can be concluded that T_(N) is dominated by electron density,and the stiffness of antiferromagnetic transition is obviously reduced by Ga substitution.The substitution effects of Ga are possibly caused by forming heterogeneous local structures,which avoids quantum critical point,superconductivity,and non-Fermi liquid states.Investigations on Gadoped Ce RhIn_(5) help to comprehend the chemical substitution effects in Ce RhIn_(5),and the interaction between heterogeneous structure and long-range antiferromagnetic states.
基金supported by the National Natural Science Foundation of China(Grant No.62471289)the Natural Science Foundation of Shanghai (Grant No.24ZR1432900)+1 种基金the Innovation Program for Quantum Science and Technology (Grant No.2021ZD0300703)Shanghai Municipal Science and Technology Major Project (Grant No.2019SHZDZX01)。
文摘Reliable detection of weak phase signals under significant channel loss and complex noise environments is a crucial step for practical applications of optical integrated communication and sensing systems. In this letter, we propose and experimentally demonstrate an enhanced long-distance weak signal transmission method assisted by weak measurement. Performing heterodyne detection and light intensity compensation on two nearly symmetric post-selected paths, the method enables real-time estimation of a time-varying phase while maintaining robustness against technical noises proportional to light intensity or photon number, detector common-mode noise, and significant attenuation over long-distance transmission. Experimental results indicate a potential phase sensitivity at the level of 10-8rad even with a signal light intensity attenuation of 48.1 d B. Potentially, combining the adaptive adjustment strategy, the method may provide a viable solution in remote weak signal detection and extraction,thereby contributing to optical integrated communication and sensing.
基金support of Dr.Z.T.Liu,Dr.Z.C.Jiang,Dr.Marta Zonno,and Dr.Sergey Gorovikovsupported in part by the National Key R&D Program of the MOST of China(Grant No.2023YFA1406300)+4 种基金the National Natural Science Foundation of China(Grant Nos.12274085,12422404,and 92477206)the New Cornerstone Science Foundation,the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0302803)Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01)The ARPES measurements used Beamlines 09U and 03U of the SSRF and Beamline QMSC of Canadian Light sourcesupported by the ME2 project from the National Natural Science Foundation of China(Contract No.11227902).
文摘LiV_(2)O_(4)is a spinel-structured compound that stands out as the first known 3d-electron system exhibiting typical heavy fermion behavior.A central question is how such strong mass renormalization emerges in the absence of f-electrons.In this work,we investigate the three-dimensional electronic structure of LiV_(2)O_(4)thin films using angle-resolved photoemission spectroscopy.We identify that an electron-like flat band is derived from a_(1g)orbitals,along with a highly dispersive e′_(g)band strongly coupled with phonons.The overall agreement with dynamical mean-field theory calculations highlights the essential role of inter-orbital Hund’s coupling in reducing the a_(1g)bandwidth to 25 meV,approaching a Mott state.Notably,we find that heavy-fermion behavior arises from additional renormalization at the a_(1g)band near the Fermi level,likely driven by many-body interactions at energy scales down to a few meV and potentially linked to geometric frustration inherent to the spinel lattice.These results provide crucial insights into the origin of the heavy fermion behavior in 3d-electron systems.
基金supported by the National Natural Science Foundation of China(Grant Nos.12192251,12334014,12404378,92480001,12134001,12174113,12174107,12474325,12404379,and 12474378)the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0301403)+1 种基金Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01)Fundamental Research Funds for the Central Universities,the Engineering Research Center for Nanophotonics&Advanced Instrument,Ministry of Education,East China Normal University(Grant No.2023nmc005).
文摘We present a compact optical delay line(ODL)with wide-range continuous tunability on thin-film lithium niobate platform.The proposed device integrates an unbalanced Mach-Zehnder interferometer(MZI)architecture with dual tunable couplers,where each coupler comprises two 2×2 multimode interferometers and a MZI phase-tuning section.Experimental results demonstrate continuous delay tuning from 0 to 293 ps through synchronized control of coupling coefficients,corresponding to a 4 cm path difference between interferometer arms.The measured delay range exhibits excellent agreement with theoretical predictions derived from ODL waveguide parameters.This result addresses critical challenges in integrated photonic systems that require precise temporal control,particularly for applications in optical communications and quantum information processing,where a wide tuning range is paramount.
基金supported by the National Natural Science Foundation of China(Grant Nos.12204173 and 12275263)the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0301900)supported by the Natural Science Foundation of Fujian Province 802 of China(Grant No.2023J02032)。
文摘The crossover between short-range and long-range(LR)universal behaviors remains a central theme in the physics of LR interacting systems.The competition between LR coupling and the Berezinskii-Kosterlitz-Thouless mechanism makes the problem more subtle and less understood in the two-dimensional(2D)XY model,a cornerstone for investigating low-dimensional phenomena and their implications in quantum computation.We study the 2D XY model with algebraically decaying interaction~1/r^(2+σ).Utilizing an advanced update strategy,we conduct LR Monte Carlo simulations of the model up to a linear size of L=8192.Our results demonstrate continuous phase transitions into a ferromagnetic phase forσ<2,which exhibit the simultaneous emergence of a long-ranged order and a power-law decaying correlation function due to the Goldstone mode.Furthermore,we fnd logarithmic scaling behaviors in the low-temperature phase atσ=2.The observed scaling behaviors in the low-temperature phase forσ≤2 agree with our theoretical analysis.Our fndings request further theoretical understanding and can be of practical application in cutting-edge experiments like Rydberg atom arrays.
基金supported by the National Key Research and Development Program of China(Grant No.2020YFC2200103)the Shandong Provincial Natural Science Foundation(Grant Nos.ZR2022LLZ006 and ZR2022LLZ011)+1 种基金the Innovation Program for Quantum Science and Technology(Grant Nos.2021ZD0300904 and 2021ZD0300903)the Key R&D Plan of Shandong Province(Grant No.2023CXPT105)。
文摘Optical phase transfer via fiber optics is the most effective method for optical frequency standard comparison on the scale below thousands of kilometers.However,the monotonic phase discrimination range of conventional optical phase-locked loops is limited,and link delays restrict the control bandwidth,which makes it a challenge to achieve a continuously reliable optical link.This paper presents an event-timing-based phase detection method that overcomes the monotonic phase discrimination range limitation of conventional phase-locked loops through dual-edge timestamp recording,achieving an optical phase measurement resolution on the order of 10 attoseconds.With such a technique,we established a 7-segment-cascaded optical link over 1402km of commercial fiber while sharing dense wavelength division multiplexing(DWDM)channels with live telecom traffic.The system maintained continuous operation for 11.7 days without phase cycle slips despite encountering 15 km aerial fiber noise up to 21000 rad^(2)·Hz^(−1)·km^(−1)at 1 Hz.Relative instabilities of the link are 3.7×10^(−15)at 1 s and 3.9×10^(−20)at 100000 s.
基金supported by the National Natural Science Foundation of China(Grant No.12474110)the National Key Research and Development Program of China(Grant No.2022YFA1403300)+1 种基金the Innovation Program for Quantum Science and Technology(Grant No.2024ZD0300103)the Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01)。
文摘In antiferromagnets,dipolar coupling is often disregarded due to the cancellation of magnetic moments between the two sublattices,so that the spin-wave dispersion is predominantly determined by exchange interactions.However,antiferromagnetic spin waves typically involve a slight misalignment of the magnetic moments on the sublattices,which gives rise to a small net magnetization enabling long-range dipolar coupling.In this paper,we investigate the role of dipolar coupling in spin-wave excitations and its influence on the resulting dispersion.Our findings show that:(i)when the Néel vector is perpendicular to the film plane or lies within the film plane and parallel to the wave vector,the dispersion branches can be divided into two groups:those unaffected by the dipolar field and those influenced by it.In these cases,the total magnetic moment remains linearly polarized,but the polarization directions differ between the two types of branches;(ii)when the Néel vector lies in the film plane and is perpendicular to the wave vector,the dipolar interactions affect both types of dispersion branches,leading to their hybridization.This hybridization alters the polarization of the magnetic moment,resulting in elliptical polarization.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12350404 and 12174066)the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0302600)+1 种基金the National Key Research and Development Program of China(Grant No.2019YFA0308404)the Science and Technology Commission of Shanghai Municipality(Grant Nos.23JC1400600 and 2019SHZDZX01)。
文摘Moirésystems have emerged as an ideal platform for exploring interaction effects and correlated states.However,most of the experimental systems are based on either triangular or honeycomb lattices.In this study,based on the self-consistent Hartree–Fock calculation,we investigate the phase diagram of the kagomélattice in a recently discovered system with two degenerateΓvalley orbitals and strong spin–orbit coupling.By focusing on the filling factors of 1/2,1/3 and 2/3,we identify various symmetry-breaking states by adjusting the screening length and dielectric constant.At the half filling,we discover that the spin–orbit coupling induces Dzyaloshinskii–Moriya interaction and stabilizes a classical magnetic state with 120°ordering.Additionally,we observe a transition to a ferromagnetic state with out-of-plane ordering.In the case of 1/3 filling,the system is ferromagnetically ordered due to the lattice frustration.Furthermore,for 2/3 filling,the system exhibits a pinned droplet state and a 120°magnetic ordered state at weak and immediate coupling strengths,respectively.For the strong coupling case,when dealing with non-integer filling,the system is always charge ordered with sublattice polarization.Our study serves as a starting point for exploring the effects of correlation in moirékagomésystems.
