Controlling the size and distribution of potential barriers within a medium of interacting particles can unveil unique collective behaviors and innovative functionalities.We introduce a unique superconducting hybrid d...Controlling the size and distribution of potential barriers within a medium of interacting particles can unveil unique collective behaviors and innovative functionalities.We introduce a unique superconducting hybrid device using a novel artificial spin ice structure composed of asymmetric nanomagnets.This structure forms a distinctive superconducting pinning potential that steers unconventional motion of superconducting vortices,thereby inducing a magnetic nonreciprocal effect,in contrast to the electric nonreciprocal effect commonly observed in superconducting diodes.Furthermore,the polarity of the magnetic nonreciprocity is in situ reversible through the tunable magnetic patterns of artificial spin ice.Our findings demonstrate that artificial spin ice not only precisely modulates superconducting characteristics but also opens the door to novel functionalities,offering a groundbreaking paradigm for superconducting electronics.展开更多
Topology played an important role in physics research during the last few decades.In particular,the quantum geometric tensor that provides local information about topological properties has attracted much attention.It...Topology played an important role in physics research during the last few decades.In particular,the quantum geometric tensor that provides local information about topological properties has attracted much attention.It will reveal interesting topological properties but have not been measured in non-Abelian systems.Here,we use a four-qubit quantum system in superconducting circuits to construct a degenerate Hamiltonian with parametric modulation.By manipulating the Hamiltonian with periodic drivings,we simulate the Bernevig-Hughes-Zhang model and obtain the quantum geometric tensor from interference oscillation.In addition,we reveal its topological feature by extracting the topological invariant,demonstrating an effective protocol for quantum simulation of a non-Abelian system.展开更多
In iron-based superconductors,the(0,π) or(π,0) nematicity,which describes an electronic anisotropy with a fourfold symmetry breaking,is well established and believed to be important for understanding the superconduc...In iron-based superconductors,the(0,π) or(π,0) nematicity,which describes an electronic anisotropy with a fourfold symmetry breaking,is well established and believed to be important for understanding the superconducting mechanism.However,how exactly such a nematic order observed in the normal state can be related to the superconducting pairing is still elusive.Here,by performing angular-dependent in-plane magnetoresistivity using ultra-thin flakes in the steep superconducting transition region,we unveil a nematic superconducting order along the(π,π) direction in electron-doped BaFe_(2-x)Ni_(x)As_(2) from under-doped to heavily overdoped regimes with x=0.065- 0.18.It shows superconducting gap maxima along the(π,π) direction rotated by 45° from the nematicity along(0, π) or(π,0) direction observed in the normal state.A similar(π,π)-type nematicity is also observed in the under-doped and optimally doped hole-type Ba1-yKyFe2 As_(2),with y=0.2-0.5.These results suggest that the(π,π) nematic superconducting order is a universal feature that needs to be taken into account in the superconducting pairing mechanism in iron-based superconductors.展开更多
Quantum-inspired imaging techniques have been proven to be effective for LiDAR with the advances of single photon detectors and computational algorithms.However,due to the disturbance of background noise and the varie...Quantum-inspired imaging techniques have been proven to be effective for LiDAR with the advances of single photon detectors and computational algorithms.However,due to the disturbance of background noise and the varies of signal in outdoor environment,the performance of LiDAR is still far from its ultimate limit set by the quantum fluctuations of coherent probe light.In this work,we propose and demonstrate a LiDAR from the detection perspective for approaching the standard quantum-limited performance.The photon numbers of echo signals are recorded by a photon-number-resolving detector and applied to overcome heavy background noise through an active photon number filter in the LiDAR.It can approach the standard quantum limit in intensity estimation in a wide photon-flux range,and achieve a Fisher information of only 0.04 dB less than the quantum Fisher information when the mean signal photon number is 10.Experimentally,a noise-free target reconstruction and imaging is demonstrated in the daytime by the proposed LiDAR.It also performs better in reflectivity resolution when taking only 1/1000 of the measurements based on on/off detection.This work provides a fundamental strategy for constructing a LiDAR to quickly extract targets and identify materials in complex environments,which is important for intelligent agents such as autonomous vehicles.展开更多
Bound states in the continuum(BICs)and exceptional points(EPs),as two distinct physical singularities represented by complex frequencies in non-Hermitian systems,have garnered significant attention and clear definitio...Bound states in the continuum(BICs)and exceptional points(EPs),as two distinct physical singularities represented by complex frequencies in non-Hermitian systems,have garnered significant attention and clear definitions in their respective fields in recent years.They share overlapping applications in areas such as high-sensitivity sensing and laser emission.However,the transition between the two,inspired by these intersections,remains largely unexplored.In this work,we reveal the transition process in a non-Hermitian two-mode system,evolving from one bound singularity to a two-dimensional exceptional ring,where the EP is the coalescent state of the quasi-Friedrich-Wintgen(FW)-BIC.This phenomenon is experimentally validated through pored dielectric metasurfaces in terahertz band.Furthermore,external pumping induced photocarriers as the dissipative perturbation,facilitates the breaking of degeneracy in the complex eigenfrequency and enables dynamic EP switching.Finally,we experimentally demonstrate a switchable terahertz beam deflection driven by the phase singularities of the EP.These findings are instrumental in advancing the development of compact devices for sensing and wavefront control within non-Hermitian systems.展开更多
The sputtering mode diagram(SMD)provides a powerful tool for comprehensive structure engineering of functional films in developing advanced electronic devices,but has not reported due to the complexity of dynamic proc...The sputtering mode diagram(SMD)provides a powerful tool for comprehensive structure engineering of functional films in developing advanced electronic devices,but has not reported due to the complexity of dynamic process and multi-parameters.Here,we report the SMD of superconductor niobium nitride(NbN)films with reactive magnetron sputtering.Poisoned mode,competing mode,and metallic mode are drawn by the boundaries identified by the current‒voltage curves of the sputtering system in the SMD,by which the phase structures and electronic properties of the NbN films can be precisely engineered.Typically,9-nm-thick NbN films grown in the optimal poisoned and competing modes are applied for superconducting nanowire single-photon detectors(SNSPDs).The as-fabricated SNSPDs have flexible performances with saturated quantum efficiency and small kinetic inductance,which enables precise manipulation of the sensitivity and speed from the SMD.This work is also providing guidance for the research of other functional films and electronic devices,which can undoubtedly promote its practical application such as dark matter detection and high-speed quantum communication.展开更多
Mid-infrared(mid-IR)single photon detectors have broad applications in science and technology,such as biomolecular spectrum analysis[1]and astronomical observations[2].Unfortunately,it is much more difficult than dete...Mid-infrared(mid-IR)single photon detectors have broad applications in science and technology,such as biomolecular spectrum analysis[1]and astronomical observations[2].Unfortunately,it is much more difficult than detecting near-infrared photons due to the significantly reduced energy of mid-IR single photon.展开更多
Spatial light modulators(SLM),capable of dynamically and spatially manipulating electromagnetic waves,have reshaped modern life in projection display and remote sensing.The progress of SLM will expedite next-generatio...Spatial light modulators(SLM),capable of dynamically and spatially manipulating electromagnetic waves,have reshaped modern life in projection display and remote sensing.The progress of SLM will expedite next-generation communication and biomedical imaging in the terahertz(THz)range.However,most current THz SLMs are adapted from optical alternatives that still need improvement in terms of uniformity,speed,and bandwidth.Here,we designed,fabricated,and characterized an 8×8THz SLM based on tunable liquid crystal metamaterial absorbers for THz single-pixel compressive imaging.We demonstrated dual-color compressive sensing(CS)imaging for dispersive objects utilizing the large frequency shift controlled by an external electric field.We developed auto-calibrated compressive sensing(ACS)algorithm to mitigate the impact of the spatially nonuniform THz incident beam and pixel modulation,which significantly improves the fidelity of reconstructed images.Furthermore,the complementary modulation at two absorption frequencies enables Hadamard masks with negative element values to be realized by frequency-switching,thereby halving the imaging time.The demonstrated imaging system paves a new route for THz single-pixel multispectral imaging with high reliability and low cost.展开更多
A frequency mixing system including microwave coupling and intermediate frequency (IF) measurement arrangements is designed. In lieu of liquid nitrogen, a pulse tube cryocooler is used to cool the whole system. With Y...A frequency mixing system including microwave coupling and intermediate frequency (IF) measurement arrangements is designed. In lieu of liquid nitrogen, a pulse tube cryocooler is used to cool the whole system. With YBa2Cu3O7/Yttrium stabilized zirconia (YBCO/YSZ) bicry-stal Josephson junction as the mixing element, 36th harmonic frequency mixing at the 8 mm waveband is obtained.展开更多
The optical coupling of superconducting nanowire single-photon detectors （SNSPDs） has always been restricted to a single-mode fiber for a limited detection area. In this study, for enhancing photon coupling, a dual-...The optical coupling of superconducting nanowire single-photon detectors （SNSPDs） has always been restricted to a single-mode fiber for a limited detection area. In this study, for enhancing photon coupling, a dual-lens system operating at 2.2 K was used to compress the beam size on the basis of the Gaussian beam theory and geometric approximation. A magnification of approximately 0.3 was obtained, and a focused spot with diameter of approximately 10 ~m was measured from a multimode fiber. Assisted with the compressed beam, a system efficiency of 55 % （1550 nm） was achieved for a SNSPD with a detection area of 10 μm × 10 μm and 62.5 pm multimode fiber coupling. At the same time, a high speed of 106 MHz was measured with the proposed system. The realization of a highly compressed optical beam reduced the optical coupling requirement and helped maintain a high speed for the SNSPD.展开更多
Dynamic manipulation of electromagnetic(EM)waves with multiple degrees of freedom plays an essential role in enhancing information processing.Currently,an enormous challenge is to realize directional terahertz(THz)hol...Dynamic manipulation of electromagnetic(EM)waves with multiple degrees of freedom plays an essential role in enhancing information processing.Currently,an enormous challenge is to realize directional terahertz(THz)holography.Recently,it was demonstrated that Janus metasurfaces could produce distinct responses to EM waves from two opposite incident directions,making multiplexed dynamic manipulation of THz waves possible.Herein,we show that thermally activated THz Janus metasurfaces integrating with phase change materials on the meta-atoms can produce asymmetric transmission with the designed phase delays.Such reconfigurable Janus metasurfaces can achieve asymmetric focusing of THz wave and directional THz holography with free-space image projections,and particularly the information can be manipulated via temperature and incident THz wave direction.This work not only offers a common strategy for realizing the reconfigurability of Janus metasurfaces,but also shows possible applications in THz optical information encryption,data storage,and smart windows.展开更多
Integrated photonics provides a route to both miniaturization of quantum key distribution(QKD)devices and enhancing their performance.A key element for achieving discrete-variable QKD is a singlephoton detector.It is ...Integrated photonics provides a route to both miniaturization of quantum key distribution(QKD)devices and enhancing their performance.A key element for achieving discrete-variable QKD is a singlephoton detector.It is highly desirable to integrate detectors onto a photonic chip to enable the realization of practical and scalable quantum networks.We realize a heterogeneously integrated,superconducting silicon-photonic chip.Harnessing the unique high-speed feature of our optical waveguide-integrated superconducting detector,we perform the first optimal Bell-state measurement(BSM)of time-bin encoded qubits generated from two independent lasers.The optimal BSM enables an increased key rate of measurement-device-independent QKD(MDI-QKD),which is immune to all attacks against the detection system and hence provides the basis for a QKD network with untrusted relays.Together with the timemultiplexed technique,we have enhanced the sifted key rate by almost one order of magnitude.With a 125-MHz clock rate,we obtain a secure key rate of 6.166 kbps over 24.0 dB loss,which is comparable to the state-of-the-art MDI-QKD experimental results with a GHz clock rate.Combined with integrated QKD transmitters,a scalable,chip-based,and cost-effective QKD network should become realizable in the near future.展开更多
The GaAs material is a major semiconductor material,and it has high electron transfer rate and direct transition energy band structure.The devices and integrated circuits fabricated on the GaAs substrates have a lot o...The GaAs material is a major semiconductor material,and it has high electron transfer rate and direct transition energy band structure.The devices and integrated circuits fabricated on the GaAs substrates have a lot of advantages such as high speed information processing.Small perturbations in the manufacturing of GaAs materials can lead to defects.The defects in the GaAs materials can degrade the performance of materials.A new method is presented in this paper for detecting the micro-defects in GaAs materials by using time resolved emissions.In this method,the micro-defects in GaAs materials are detected by making use of the photon emission features of microdefects.The strength of the emitted photons from the micro-defects is increased by applying the electric current or the periodic pulse signals to GaAs materials.The singlephoton detector is used to detect the photon emissions of the micro-defects.The time resolved photon emissions and single-photon detection are used to record and compare the amounts of the emitted photons that come from the given regions of the normal GaAs materials and the defective GaAs materials.A lot of experimental results show that the micro-defects in the GaAs materials can be detected by using the method proposed in this paper.展开更多
Laser communication using photons should consider not only the transmission environment’s effects,but also the performance of the single-photon detector used and the photon number distribution.Photon communication ba...Laser communication using photons should consider not only the transmission environment’s effects,but also the performance of the single-photon detector used and the photon number distribution.Photon communication based on the superconducting nanowire single-photon detector(SNSPD)is a new technology that addresses the current sensitivity limitations at the level of single photons in deep space communication.The communication’s bit error rate(BER)is limited by dark noise in the space environment and the photon number distribution with a traditional single-pixel SNSPD,which is unable to resolve the photon number distribution.In this work,an enhanced photon communication method was proposed based on the photon number resolving function of four-pixel array SNSPDs.A simulated picture transmission was carried out,and the error rate in this counting mode can be reduced by 2 orders of magnitude when compared with classical optical communication.However,in the communication mode using photon-enhanced counting,the four-pixel response amplitude for counting was found to restrain the communication rate,and this counting mode is extremely dependent on the incident light intensity through experiments,which limits the sensitivity and speed of the SNSPD array’s performance advantage.Therefore,a BER theoretical calculation model for laser communication was presented using the Bayesian estimation algorithm in order to analyze the selection of counting methods for information acquisition under different light intensities and to make better use of the SNSPD array’s high sensitivity and speed and thus to obtain a lower BER.The counting method and theoretical model proposed in this work refer to array SNSPDs in the deep space field.展开更多
Fiber components form the standard not only in modern telecommunication but also for future quantum information technology. For high-performance single-photon detection, superconducting nanowire single-photon detector...Fiber components form the standard not only in modern telecommunication but also for future quantum information technology. For high-performance single-photon detection, superconducting nanowire single-photon detectors (SPDs) are typically fabricated on a silicon chip and fiber-coupled for easy handling and usage. The fiber- to-chip interface hinders the SPD from being an all-fiber device for full utilization of its excellent performance. Here, we report a scheme of SPD that is directly fabricated on the fiber tip. A bury-and-planar fabrication technique is developed to improve the roughness of the substrate for all-fiber detectors’ performance for single-photon detection with amorphous molybdenum silicide (MoSi) nanowires. The low material selectivity and universal planar process enable fabrication and packaging on a large scale. Such a detector responds to a broad wavelength range from 405 nm to 1550 nm at a dark count rate of 100 cps. The relaxation time of the response pulse is ~ 15 ns, which is comparable to that of on-chip SPDs. Therefore, this device is free from fiber-to-chip coupling and easy packaging for all-fiber quantum information systems.展开更多
Superconducting nanowire single-photon detectors(SNSPDs)with low energy gaps exhibit superior single-photon sensitivity at infrared wavelengths[1],and state-of-the-art SNSPDs have the potential to meet the stringent d...Superconducting nanowire single-photon detectors(SNSPDs)with low energy gaps exhibit superior single-photon sensitivity at infrared wavelengths[1],and state-of-the-art SNSPDs have the potential to meet the stringent demands of mid-IR(MIR)detection[2].However,the nanowire thickness(~λ/1000-λ/600)and width(~λ/166-λ/60)are much smaller than those at MIR wavelengths,which results in weak absorption with a low detection efficiency[3].展开更多
Amorphous materials are attractive candidates for fabricating the superconducting nanowire single-photon detectors(SNSPDs) due to their superior tolerance and scalability over crystalline niobium nitride. However, the...Amorphous materials are attractive candidates for fabricating the superconducting nanowire single-photon detectors(SNSPDs) due to their superior tolerance and scalability over crystalline niobium nitride. However, the reduced superconducting transition temperature degenerates both operating temperature and saturation efficiency. Herein, the SNSPD(6.5 nm thickness and 50 nm width) based on the amorphous Mo0.8Si0.2 film with a high optical absorption coefficient demonstrates close-to-unity intrinsic detection efficiency for 1550 nm photons from 75 m K to 2.2 K. Further, a high-performance array SNSPD with optimized 90 nm-width wires is also demonstrated. As-fabricated uniform 4-pixel SNSPD exhibits a saturation plateau for the photon counts at 2.2 K,which overcomes the limitation of operation at low temperature(< 1 K) for traditional amorphous SNSPDs.Coupled with superior intrinsic quantum efficiency, highly efficient photon counts, and low dark count ratio, this detector paves a way for achieving high efficiency and superior yield for large array systems.展开更多
The principles and characteristics of rapid single flux quantum (RSFQ) circ- uits are discussed. According to these theories, we have designed RSFQ inverter, XOR cell and shift registers relative to the pseudo random ...The principles and characteristics of rapid single flux quantum (RSFQ) circ- uits are discussed. According to these theories, we have designed RSFQ inverter, XOR cell and shift registers relative to the pseudo random generator. Based on these cells, the RSFQ pseudo random generator is given. Compared with the simulation result of another mathematical model that is established by MATLAB, the design of the RSFQ pseudo random generator is proved to be reasonable and meets our expectations.展开更多
We demonstrate the effect of different coupling strengths between a microscopic two-level system(TLS)and a microwave field on the dynamics of a qubit—TLS system when the bipartite system is subject to resonant microw...We demonstrate the effect of different coupling strengths between a microscopic two-level system(TLS)and a microwave field on the dynamics of a qubit—TLS system when the bipartite system is subject to resonant microwave driving.Rabi beating with a different TLSmicrowave coupling strength is demonstrated in simulations.Entanglement,quantified by the concurrence between the qubit and TLS,both for pure states and mixed states,is simulated.When decoherence is considered,entanglement of the bipartite system oscillates with damping and exhibits entanglement sudden death and/or entanglement sudden death and revival.展开更多
We measured experimentally the spectrum of a superconducting phase qubit.An avoided energy-level crossing is obviously observed,which is due to the coupling to a microscopic two-level system.With different theoretical...We measured experimentally the spectrum of a superconducting phase qubit.An avoided energy-level crossing is obviously observed,which is due to the coupling to a microscopic two-level system.With different theoretical methods,we simulated the spectrum,from which we can obtain the coupled system’s parameters and the coupling mechanism.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.62288101 and 62274086)the National Key R&D Program of China(Grant No.2021YFA0718802)the Jiangsu Outstanding Postdoctoral Program。
文摘Controlling the size and distribution of potential barriers within a medium of interacting particles can unveil unique collective behaviors and innovative functionalities.We introduce a unique superconducting hybrid device using a novel artificial spin ice structure composed of asymmetric nanomagnets.This structure forms a distinctive superconducting pinning potential that steers unconventional motion of superconducting vortices,thereby inducing a magnetic nonreciprocal effect,in contrast to the electric nonreciprocal effect commonly observed in superconducting diodes.Furthermore,the polarity of the magnetic nonreciprocity is in situ reversible through the tunable magnetic patterns of artificial spin ice.Our findings demonstrate that artificial spin ice not only precisely modulates superconducting characteristics but also opens the door to novel functionalities,offering a groundbreaking paradigm for superconducting electronics.
基金supported by the Key R&D Program of Guangdong Province(Grant No.2018B030326001)the National Natural Science Foundation of China(Grant Nos.11474152,12074179,U21A20436,and 61521001)the Natural Science Foundation of Jiangsu Province(Grant No.BE2021015-1).
文摘Topology played an important role in physics research during the last few decades.In particular,the quantum geometric tensor that provides local information about topological properties has attracted much attention.It will reveal interesting topological properties but have not been measured in non-Abelian systems.Here,we use a four-qubit quantum system in superconducting circuits to construct a degenerate Hamiltonian with parametric modulation.By manipulating the Hamiltonian with periodic drivings,we simulate the Bernevig-Hughes-Zhang model and obtain the quantum geometric tensor from interference oscillation.In addition,we reveal its topological feature by extracting the topological invariant,demonstrating an effective protocol for quantum simulation of a non-Abelian system.
基金Supported by the National Natural Science Foundation of China(Grant Nos.61771234,61727805,11674157,11674158,11774152,11822405,61521001,6157121961501222)+6 种基金the National Key Projects for Research and Development of China(Grant Nos.2016YFA0300401,2017YFB0503302,2017YFA03040022017YFB0503300)the start-up funding from ShanghaiTech University,Innovative Research Team in University(PCSIRT)the Natural Science Foundation of Shanghai Municipality(Grant No.20ZR1436100)the Science and Technology Commission of Shanghai Municipality(Grant No.YDZX20203100001438)Jiangsu Key Laboratory of Advanced Techniques for Manipulating Electromagnetic Waves,Natural Science Foundation of Jiangsu Province(Grant No.BK20180006)the Fundamental Research Funds for the Central Universities(Grant No.020414380117)。
文摘In iron-based superconductors,the(0,π) or(π,0) nematicity,which describes an electronic anisotropy with a fourfold symmetry breaking,is well established and believed to be important for understanding the superconducting mechanism.However,how exactly such a nematic order observed in the normal state can be related to the superconducting pairing is still elusive.Here,by performing angular-dependent in-plane magnetoresistivity using ultra-thin flakes in the steep superconducting transition region,we unveil a nematic superconducting order along the(π,π) direction in electron-doped BaFe_(2-x)Ni_(x)As_(2) from under-doped to heavily overdoped regimes with x=0.065- 0.18.It shows superconducting gap maxima along the(π,π) direction rotated by 45° from the nematicity along(0, π) or(π,0) direction observed in the normal state.A similar(π,π)-type nematicity is also observed in the under-doped and optimally doped hole-type Ba1-yKyFe2 As_(2),with y=0.2-0.5.These results suggest that the(π,π) nematic superconducting order is a universal feature that needs to be taken into account in the superconducting pairing mechanism in iron-based superconductors.
基金supported by Frontier Technologies R&D Program of Jiangsu(No.BF2024058)the National Key Research and Development Program of China(No.2023YFC2205802)+4 种基金the Key-Area Research and Development Program of Guangdong Province(2020B0303020001)National Natural Science Foundation of China(No.12461160276)the Innovation Program for Quantum Science and Technology(No.2021ZD0303401)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)the Jiangsu Provincial Key Laboratory of Advanced Manipulating Technique of Electromagnetic Waves.
文摘Quantum-inspired imaging techniques have been proven to be effective for LiDAR with the advances of single photon detectors and computational algorithms.However,due to the disturbance of background noise and the varies of signal in outdoor environment,the performance of LiDAR is still far from its ultimate limit set by the quantum fluctuations of coherent probe light.In this work,we propose and demonstrate a LiDAR from the detection perspective for approaching the standard quantum-limited performance.The photon numbers of echo signals are recorded by a photon-number-resolving detector and applied to overcome heavy background noise through an active photon number filter in the LiDAR.It can approach the standard quantum limit in intensity estimation in a wide photon-flux range,and achieve a Fisher information of only 0.04 dB less than the quantum Fisher information when the mean signal photon number is 10.Experimentally,a noise-free target reconstruction and imaging is demonstrated in the daytime by the proposed LiDAR.It also performs better in reflectivity resolution when taking only 1/1000 of the measurements based on on/off detection.This work provides a fundamental strategy for constructing a LiDAR to quickly extract targets and identify materials in complex environments,which is important for intelligent agents such as autonomous vehicles.
基金supported by the National Nature Science Foundation of China(NSFC)(Nos.62222106,62288101,62027807,92163216,92463308,62071217,and 62275118)the Fundamental Research Funds for the Central Universities.
文摘Bound states in the continuum(BICs)and exceptional points(EPs),as two distinct physical singularities represented by complex frequencies in non-Hermitian systems,have garnered significant attention and clear definitions in their respective fields in recent years.They share overlapping applications in areas such as high-sensitivity sensing and laser emission.However,the transition between the two,inspired by these intersections,remains largely unexplored.In this work,we reveal the transition process in a non-Hermitian two-mode system,evolving from one bound singularity to a two-dimensional exceptional ring,where the EP is the coalescent state of the quasi-Friedrich-Wintgen(FW)-BIC.This phenomenon is experimentally validated through pored dielectric metasurfaces in terahertz band.Furthermore,external pumping induced photocarriers as the dissipative perturbation,facilitates the breaking of degeneracy in the complex eigenfrequency and enables dynamic EP switching.Finally,we experimentally demonstrate a switchable terahertz beam deflection driven by the phase singularities of the EP.These findings are instrumental in advancing the development of compact devices for sensing and wavefront control within non-Hermitian systems.
基金supported by the National Natural Science Foundation of China(No.12033002)the Civil Aerospace Technology Research Project(Nos.D040305 and D010104)+3 种基金the Natural Science Foundation of Jiangsu Province(No.BK20230777)the Innovation Program for Quantum Science and Technology(No.2021ZD0303401)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)the Jiangsu Provincial Key Laboratory of Advanced Manipulating Technique of Electromagnetic Waves.
文摘The sputtering mode diagram(SMD)provides a powerful tool for comprehensive structure engineering of functional films in developing advanced electronic devices,but has not reported due to the complexity of dynamic process and multi-parameters.Here,we report the SMD of superconductor niobium nitride(NbN)films with reactive magnetron sputtering.Poisoned mode,competing mode,and metallic mode are drawn by the boundaries identified by the current‒voltage curves of the sputtering system in the SMD,by which the phase structures and electronic properties of the NbN films can be precisely engineered.Typically,9-nm-thick NbN films grown in the optimal poisoned and competing modes are applied for superconducting nanowire single-photon detectors(SNSPDs).The as-fabricated SNSPDs have flexible performances with saturated quantum efficiency and small kinetic inductance,which enables precise manipulation of the sensitivity and speed from the SMD.This work is also providing guidance for the research of other functional films and electronic devices,which can undoubtedly promote its practical application such as dark matter detection and high-speed quantum communication.
基金supported by the National Key R&D Program of China (2017YFA0304002)the National Natural Science Foundation of China (12033002, 61571217, 61521001, 61801206 and 11227904)+1 种基金the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)the Jiangsu Provincial Key Laboratory of Advanced Manipulating Technique of Electromagnetic Waves
文摘Mid-infrared(mid-IR)single photon detectors have broad applications in science and technology,such as biomolecular spectrum analysis[1]and astronomical observations[2].Unfortunately,it is much more difficult than detecting near-infrared photons due to the significantly reduced energy of mid-IR single photon.
基金supported by the National Key Research and Development Program of China(2017YFA0700202,2021YFB2800701)National Nature Science Foundation of China(61731010,62071217,61971465,62027807,61871212,62025108,62035014)Fundamental Research Funds for the Central Universities,and Research Fund for Jiangsu Key Laboratory of Advanced Techniques for Manipulatinp Electromagnetic Waves.
文摘Spatial light modulators(SLM),capable of dynamically and spatially manipulating electromagnetic waves,have reshaped modern life in projection display and remote sensing.The progress of SLM will expedite next-generation communication and biomedical imaging in the terahertz(THz)range.However,most current THz SLMs are adapted from optical alternatives that still need improvement in terms of uniformity,speed,and bandwidth.Here,we designed,fabricated,and characterized an 8×8THz SLM based on tunable liquid crystal metamaterial absorbers for THz single-pixel compressive imaging.We demonstrated dual-color compressive sensing(CS)imaging for dispersive objects utilizing the large frequency shift controlled by an external electric field.We developed auto-calibrated compressive sensing(ACS)algorithm to mitigate the impact of the spatially nonuniform THz incident beam and pixel modulation,which significantly improves the fidelity of reconstructed images.Furthermore,the complementary modulation at two absorption frequencies enables Hadamard masks with negative element values to be realized by frequency-switching,thereby halving the imaging time.The demonstrated imaging system paves a new route for THz single-pixel multispectral imaging with high reliability and low cost.
基金This work was supported by the Ministry of Science and Technology of China (Grant No. G19990646).
文摘A frequency mixing system including microwave coupling and intermediate frequency (IF) measurement arrangements is designed. In lieu of liquid nitrogen, a pulse tube cryocooler is used to cool the whole system. With YBa2Cu3O7/Yttrium stabilized zirconia (YBCO/YSZ) bicry-stal Josephson junction as the mixing element, 36th harmonic frequency mixing at the 8 mm waveband is obtained.
基金supported by the National Basic Research Program of China(2011CBA02)the National Natural Science Foundation of China(61471189,11227904 and 61101012)
文摘The optical coupling of superconducting nanowire single-photon detectors （SNSPDs） has always been restricted to a single-mode fiber for a limited detection area. In this study, for enhancing photon coupling, a dual-lens system operating at 2.2 K was used to compress the beam size on the basis of the Gaussian beam theory and geometric approximation. A magnification of approximately 0.3 was obtained, and a focused spot with diameter of approximately 10 ~m was measured from a multimode fiber. Assisted with the compressed beam, a system efficiency of 55 % （1550 nm） was achieved for a SNSPD with a detection area of 10 μm × 10 μm and 62.5 pm multimode fiber coupling. At the same time, a high speed of 106 MHz was measured with the proposed system. The realization of a highly compressed optical beam reduced the optical coupling requirement and helped maintain a high speed for the SNSPD.
基金This study was supported by the National Key Research and Development Program of China(2017YFA0700202,2021YFB2800701)National Nature Science Foundation of China(62288101,91963128,62071215,62071217,62027807,62035014)Fundamental Research Funds for the Central Universities,and Research Fund for Jiangsu Key Laboratory of Advanced Techniques for Manipulating Electromagnetic Waves.J.W.acknowledges the support from Xiaomi Young Scholar Program.
文摘Dynamic manipulation of electromagnetic(EM)waves with multiple degrees of freedom plays an essential role in enhancing information processing.Currently,an enormous challenge is to realize directional terahertz(THz)holography.Recently,it was demonstrated that Janus metasurfaces could produce distinct responses to EM waves from two opposite incident directions,making multiplexed dynamic manipulation of THz waves possible.Herein,we show that thermally activated THz Janus metasurfaces integrating with phase change materials on the meta-atoms can produce asymmetric transmission with the designed phase delays.Such reconfigurable Janus metasurfaces can achieve asymmetric focusing of THz wave and directional THz holography with free-space image projections,and particularly the information can be manipulated via temperature and incident THz wave direction.This work not only offers a common strategy for realizing the reconfigurability of Janus metasurfaces,but also shows possible applications in THz optical information encryption,data storage,and smart windows.
基金supported by the National Key Research and Development Program of China(Nos.2017YFA0303704,2019YFA0308700,and 2017YFA0304002)the National Natural Science Foundation of China(Nos.11690032,11321063,and 12033002)+2 种基金the NSFC-BRICS(No.61961146001)the Leading-Edge Technology Program of Jiangsu Natural Science Foundation(No.BK20192001)the Fundamental Research Funds for the Central Universities.
文摘Integrated photonics provides a route to both miniaturization of quantum key distribution(QKD)devices and enhancing their performance.A key element for achieving discrete-variable QKD is a singlephoton detector.It is highly desirable to integrate detectors onto a photonic chip to enable the realization of practical and scalable quantum networks.We realize a heterogeneously integrated,superconducting silicon-photonic chip.Harnessing the unique high-speed feature of our optical waveguide-integrated superconducting detector,we perform the first optimal Bell-state measurement(BSM)of time-bin encoded qubits generated from two independent lasers.The optimal BSM enables an increased key rate of measurement-device-independent QKD(MDI-QKD),which is immune to all attacks against the detection system and hence provides the basis for a QKD network with untrusted relays.Together with the timemultiplexed technique,we have enhanced the sifted key rate by almost one order of magnitude.With a 125-MHz clock rate,we obtain a secure key rate of 6.166 kbps over 24.0 dB loss,which is comparable to the state-of-the-art MDI-QKD experimental results with a GHz clock rate.Combined with integrated QKD transmitters,a scalable,chip-based,and cost-effective QKD network should become realizable in the near future.
基金supported by the National Natural Science Foundation of China (61072028)the Project of Department of Education of Guangdong Province (2012KJCX0040)Guangdong Province and Chinese Ministry of Education Cooperation Project of Industry,Education and Academy (2009B090300339)
文摘The GaAs material is a major semiconductor material,and it has high electron transfer rate and direct transition energy band structure.The devices and integrated circuits fabricated on the GaAs substrates have a lot of advantages such as high speed information processing.Small perturbations in the manufacturing of GaAs materials can lead to defects.The defects in the GaAs materials can degrade the performance of materials.A new method is presented in this paper for detecting the micro-defects in GaAs materials by using time resolved emissions.In this method,the micro-defects in GaAs materials are detected by making use of the photon emission features of microdefects.The strength of the emitted photons from the micro-defects is increased by applying the electric current or the periodic pulse signals to GaAs materials.The singlephoton detector is used to detect the photon emissions of the micro-defects.The time resolved photon emissions and single-photon detection are used to record and compare the amounts of the emitted photons that come from the given regions of the normal GaAs materials and the defective GaAs materials.A lot of experimental results show that the micro-defects in the GaAs materials can be detected by using the method proposed in this paper.
基金National Key Research and Development Program of China(2017YFA0304002)National Natural Science Foundation of China(61571217,61521001,61801206,11227904)+1 种基金Priority Academic Program Development of Jiangsu Higher Education InstitutionsNanjing University。
文摘Laser communication using photons should consider not only the transmission environment’s effects,but also the performance of the single-photon detector used and the photon number distribution.Photon communication based on the superconducting nanowire single-photon detector(SNSPD)is a new technology that addresses the current sensitivity limitations at the level of single photons in deep space communication.The communication’s bit error rate(BER)is limited by dark noise in the space environment and the photon number distribution with a traditional single-pixel SNSPD,which is unable to resolve the photon number distribution.In this work,an enhanced photon communication method was proposed based on the photon number resolving function of four-pixel array SNSPDs.A simulated picture transmission was carried out,and the error rate in this counting mode can be reduced by 2 orders of magnitude when compared with classical optical communication.However,in the communication mode using photon-enhanced counting,the four-pixel response amplitude for counting was found to restrain the communication rate,and this counting mode is extremely dependent on the incident light intensity through experiments,which limits the sensitivity and speed of the SNSPD array’s performance advantage.Therefore,a BER theoretical calculation model for laser communication was presented using the Bayesian estimation algorithm in order to analyze the selection of counting methods for information acquisition under different light intensities and to make better use of the SNSPD array’s high sensitivity and speed and thus to obtain a lower BER.The counting method and theoretical model proposed in this work refer to array SNSPDs in the deep space field.
基金Innovation Program for Quantum Science and Technology(No.2021ZD0303401)National Key R&D Program of China(2019YFA0705000,2022YFA120018800)+5 种基金National Natural Science Foundation of China(12033002,62071218,62071214,61801206,12161141009,12074175,51890861,62293520,62293523)Key-Area Research and Development Program of Guangdong Province(2020B0303020001)Leading-edge Technology Program of Jiangsu Natural Science Foundation(BK20192001)Zhangjiang Laboratory(ZJSP21A001)Fundamental Research Funds for the Central Universities,the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)Recruitment Program for Young Professionals,the Qing Lan Project and the Jiangsu Provincial Key Laboratory of Advanced Manipulating Technique of Electromagnetic Waves,Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX22_0141),Jiangsu Planned Projects for Postdoctoral Research Funds(2021K259B).
文摘Fiber components form the standard not only in modern telecommunication but also for future quantum information technology. For high-performance single-photon detection, superconducting nanowire single-photon detectors (SPDs) are typically fabricated on a silicon chip and fiber-coupled for easy handling and usage. The fiber- to-chip interface hinders the SPD from being an all-fiber device for full utilization of its excellent performance. Here, we report a scheme of SPD that is directly fabricated on the fiber tip. A bury-and-planar fabrication technique is developed to improve the roughness of the substrate for all-fiber detectors’ performance for single-photon detection with amorphous molybdenum silicide (MoSi) nanowires. The low material selectivity and universal planar process enable fabrication and packaging on a large scale. Such a detector responds to a broad wavelength range from 405 nm to 1550 nm at a dark count rate of 100 cps. The relaxation time of the response pulse is ~ 15 ns, which is comparable to that of on-chip SPDs. Therefore, this device is free from fiber-to-chip coupling and easy packaging for all-fiber quantum information systems.
基金National Natural Science Foundation of China(12033002,62275118,62071218,62101240,62227820,12161141009,and 62288101)Innovation Program for Quantum Science and Technology(2021ZD0303401)+2 种基金Civil Aerospace Technology Research Project(D040305)Fundamental Research Funds for the Central Universities,the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)Postgraduate Research&Practice Innovation Program of Jiangsu Province.
文摘Superconducting nanowire single-photon detectors(SNSPDs)with low energy gaps exhibit superior single-photon sensitivity at infrared wavelengths[1],and state-of-the-art SNSPDs have the potential to meet the stringent demands of mid-IR(MIR)detection[2].However,the nanowire thickness(~λ/1000-λ/600)and width(~λ/166-λ/60)are much smaller than those at MIR wavelengths,which results in weak absorption with a low detection efficiency[3].
基金National Key Research and Development Program of China (2017YFA0304002)National Natural Science Foundation of China (12033002, 62071218, 61521001, 62071214, 61801206, 11227904)+5 种基金Key-Area Research and Development Program of Guangdong Province(2020B0303020001)Fundamental Research Funds for the Central UniversitiesPriority Academic Program Development of Jiangsu Higher Education InstitutionsRecruitment Program for Young ProfessionalsQing Lan ProjectJiangsu Provincial Key Laboratory of Advanced Manipulating Technique of Electromagnetic Waves。
文摘Amorphous materials are attractive candidates for fabricating the superconducting nanowire single-photon detectors(SNSPDs) due to their superior tolerance and scalability over crystalline niobium nitride. However, the reduced superconducting transition temperature degenerates both operating temperature and saturation efficiency. Herein, the SNSPD(6.5 nm thickness and 50 nm width) based on the amorphous Mo0.8Si0.2 film with a high optical absorption coefficient demonstrates close-to-unity intrinsic detection efficiency for 1550 nm photons from 75 m K to 2.2 K. Further, a high-performance array SNSPD with optimized 90 nm-width wires is also demonstrated. As-fabricated uniform 4-pixel SNSPD exhibits a saturation plateau for the photon counts at 2.2 K,which overcomes the limitation of operation at low temperature(< 1 K) for traditional amorphous SNSPDs.Coupled with superior intrinsic quantum efficiency, highly efficient photon counts, and low dark count ratio, this detector paves a way for achieving high efficiency and superior yield for large array systems.
基金The National Center for Research and Development on Superconductivity of China and the National Science Fund for Distinguished Young Scholars (B) (Grant No. 69801004).
文摘The principles and characteristics of rapid single flux quantum (RSFQ) circ- uits are discussed. According to these theories, we have designed RSFQ inverter, XOR cell and shift registers relative to the pseudo random generator. Based on these cells, the RSFQ pseudo random generator is given. Compared with the simulation result of another mathematical model that is established by MATLAB, the design of the RSFQ pseudo random generator is proved to be reasonable and meets our expectations.
基金supported by the National Basic Research Program of China (2011CBA00107 and 2011CBA00202)the National Natural Science Foundation of China (61371036,11074114 and 11227904)+1 种基金the Natural Science Foundation of Jiangsu (BK2012013)the CAEP THz Science and Technology Foundation (CAEPTHZ201206)
文摘We demonstrate the effect of different coupling strengths between a microscopic two-level system(TLS)and a microwave field on the dynamics of a qubit—TLS system when the bipartite system is subject to resonant microwave driving.Rabi beating with a different TLSmicrowave coupling strength is demonstrated in simulations.Entanglement,quantified by the concurrence between the qubit and TLS,both for pure states and mixed states,is simulated.When decoherence is considered,entanglement of the bipartite system oscillates with damping and exhibits entanglement sudden death and/or entanglement sudden death and revival.
文摘We measured experimentally the spectrum of a superconducting phase qubit.An avoided energy-level crossing is obviously observed,which is due to the coupling to a microscopic two-level system.With different theoretical methods,we simulated the spectrum,from which we can obtain the coupled system’s parameters and the coupling mechanism.
