By using one-dimensional tight-binding model modified to include electron-electric field interaction and electron-electron interaction,we theoretically explore the polarization process of exciton and biexciton in cis-...By using one-dimensional tight-binding model modified to include electron-electric field interaction and electron-electron interaction,we theoretically explore the polarization process of exciton and biexciton in cis-polyacetylene.The dynamical simulation is performed by adopting the non-adiabatic evolution approach.The results show that under the effect of moderate electric field,when the strength of electron-electron interaction is weak,the singlet exciton is stable but its polarization presents obvious oscillation.With the enhancement of interaction,it is dissociated into polaron pairs,the spin-flip of which can be observed through modulating the interaction strength.For the triplet exciton,the strong electron-electron interaction restrains its normal polarization,but it is still stable.In the case of biexciton,the strong electron-electron interaction not only dissociate it,but also flip its charge distribution.The yield of the possible states formed after the dissociation of exciton and biexciton is also calculated.展开更多
Nyquist pulses have wide applications in many areas,from electronics to optics.Mode-locked lasers are ideal platforms to generate such pulses.However,how to generate high-quality Nyquist pulses in mode-locked lasers r...Nyquist pulses have wide applications in many areas,from electronics to optics.Mode-locked lasers are ideal platforms to generate such pulses.However,how to generate high-quality Nyquist pulses in mode-locked lasers remains elusive.We address this problem by managing different physical effects in mode-locked fiber lasers through extensive numerical simulations.We find that net dispersion,linear loss,gain and filter shaping can affect the quality of Nyquist pulses significantly.We also demonstrate that Nyquist pulses experience similariton shaping due to the nonlinear attractor effect in the gain medium.Our work may contribute to the design of Nyquist pulse sources and enrich the understanding of pulse shaping dynamics in mode-locked lasers.展开更多
Perfect vector beams are a class of special vector beams with invariant radius and intensity profiles under changing topological charges.However,with the limitation of current devices,the generation of these vector be...Perfect vector beams are a class of special vector beams with invariant radius and intensity profiles under changing topological charges.However,with the limitation of current devices,the generation of these vector beams is limited in the visible and infrared wavebands.Herein,we generate perfect vector beams in the ultraviolet region assisted by nonlinear frequency conversion.Experimental and simulation results show that the radius of the generated ultraviolet perfect vector beams remains invariant and is thus independent of the topological charge.Furthermore,we measure the power of the generated ultraviolet perfect vector beams with the change of their topological charges.This study provides an alternative approach to generating perfect vector beams for ultraviolet wavebands and may promote their application to optical trapping and optical communication.展开更多
Breakdown spectroscopy is a valuable tool for determining elements in solids,liquids,and gases.All materials in the breakdown region can be ionized and dissociated into highly excited fragments and emit characteristic...Breakdown spectroscopy is a valuable tool for determining elements in solids,liquids,and gases.All materials in the breakdown region can be ionized and dissociated into highly excited fragments and emit characteristic fluorescence spectra.In this sense,the elemental composition of materials can be evaluated by detecting the fluorescence spectrum.This paper reviews the recent developments in laser-induced breakdown spectroscopy.The traditional laser-induced breakdown spectroscopy,filament-induced breakdown spectroscopy,plasma grating,and multidimensional plasma grating-induced breakdown spectroscopy are introduced.There are also some proposals for applications of plasma gratings,such as laser ablation,laser deposition,and laser catalysis of chemical reactions in conjunction with research on the properties of plasma gratings.展开更多
Recently,integrated photonics has attracted considerable interest owing to its wide application in optical communication and quantum technologies.Among the numerous photonic materials,lithium niobate film on insulator...Recently,integrated photonics has attracted considerable interest owing to its wide application in optical communication and quantum technologies.Among the numerous photonic materials,lithium niobate film on insulator(LNOI)has become a promising photonic platform owing to its electro-optic and nonlinear optical properties along with ultralow-loss and high-confinement nanophotonic lithium niobate waveguides fabricated by the complementary metal-oxide-semiconductor(CMOS)-compatible microstructure engineering of LNOI.Furthermore,ferroelectric domain engineering in combination with nanophotonic waveguides on LNOI is gradually accelerating the development of integrated nonlinear photonics,which will play an important role in quantum technologies because of its ability to be integrated with the generation,processing,and auxiliary detection of the quantum states of light.Herein,we review the recent progress in CMOS-compatible microstructure engineering and domain engineering of LNOI for integrated lithium niobate photonics involving photonic modulation and nonlinear photonics.We believe that the great progress in integrated photonics on LNOI will lead to a new generation of techniques.Thus,there remains an urgent need for efficient methods for the preparation of LNOI that are suitable for large-scale and low-cost manufacturing of integrated photonic devices and systems.展开更多
In this paper, we demonstrated a series of short-living mode-locking(ML) states(each lasting a few to a hundred microseconds) that happened before a fiber laser reached a steady ML state.With time-stretched dispersion...In this paper, we demonstrated a series of short-living mode-locking(ML) states(each lasting a few to a hundred microseconds) that happened before a fiber laser reached a steady ML state.With time-stretched dispersion Fourier transform spectroscopy, a rich diversity of transient multi-pulse dynamics were revealed spectrally and temporally.As a result, we found that the formation of the short-living ML states was related to abundant pump power, and their decaying evolution dynamics were possibly governed by gain depletion and recovery.Our results revealed unexpected transient lasing behaviors of a soliton laser and thus might be useful to understand the complex dynamics of mode-locked lasers.展开更多
Orbital angular momentum(OAM)is a fundamental physical characteristic to describe laser fields with a spiral phase structure.Vortex beams carrying OAMs have attracted more and more attention in recent years.However,th...Orbital angular momentum(OAM)is a fundamental physical characteristic to describe laser fields with a spiral phase structure.Vortex beams carrying OAMs have attracted more and more attention in recent years.However,the wavefront of OAM light would be destroyed when it passes through scattering media.Here,based on the feedback-based wavefront shaping method,we reconstitute OAM wavefronts behind strongly scattering media.The intensity of light with desired OAM states is enhanced to 150 times.This study provides a method to manipulate OAMs of scattered light and is of great significance for OAM optical communication and imaging to overcome complex environment interference.展开更多
In the quest to realize a scalable quantum network,semiconductor quantum dots(QDs)offer distinct advantages,including high single-photon efficiency and indistinguishability,high repetition rate(tens of gigahertz with ...In the quest to realize a scalable quantum network,semiconductor quantum dots(QDs)offer distinct advantages,including high single-photon efficiency and indistinguishability,high repetition rate(tens of gigahertz with Purcell enhancement),interconnectivity with spin qubits,and a scalable on-chip platform.However,in the past two decades,the visibility of quantum interference between independent QDs rarely went beyond the classical limit of 50%,and the distances were limited from a few meters to kilometers.Here,we report quantum interference between two single photons from independent QDs separated by a 302 km optical fiber.The single photons are generated from resonantly driven single QDs deterministically coupled to microcavities.Quantum frequency conversions are used to eliminate the QD inhomogeneity and shift the emission wavelength to the telecommunication band.The observed interference visibility is 0.670.02(0.930.04)without(with)temporal filtering.Feasible improvements can further extend the distance to∼600 km.Our work represents a key step to long-distance solid-state quantum networks.展开更多
Atherosclerotic cardio-cerebral vascular disease is the most common disease that threatens human health.Many researches indicated that oxidatively modified low-density lipoprotein[ox-LDL]is a key pathogenic factor of ...Atherosclerotic cardio-cerebral vascular disease is the most common disease that threatens human health.Many researches indicated that oxidatively modified low-density lipoprotein[ox-LDL]is a key pathogenic factor of atherosclero-sis.Here,we report the change of the secondary structure of ox-LDL caused by photoirradiation in an optofluidic resonator.The content ratios of amphipathic o-helices and β-sheets of ox-LDL are changed under laser beam ilumination,resulting in an increasing binding rate of ox-LDL and ox-LDL antibodies.Our findings may provide a potential way for clinical athero-sclerosis treatment and prompt recovery rate of atherosclerotic cardio-cerebral vascular disease by optical technology and immunotherapy.展开更多
Measurement-device-independent quantum key distribution(MDI-QKD)protocol can remove all the loopholes of the detection devices and,thus,has attracted much attention.Based on the technique of single-photon interference...Measurement-device-independent quantum key distribution(MDI-QKD)protocol can remove all the loopholes of the detection devices and,thus,has attracted much attention.Based on the technique of single-photon interference,we propose a modified MDI-QKD protocol with phase post-selection.We prove the security of the announcement of the private phases in the X basis and show how to apply the phase post-selection method to the double-scanning four-intensity MDI-QKD protocol.The numerical results show that the phase postselection method can significantly improve the key rates at all distances.In the double-scanning method,two parameters need to be scanned in the calculation of the final key rate,and the global parameter optimization is pretty time-consuming.We propose an accelerated method that can greatly reduce the running time of the global parameter optimization program.This makes the method practically useful in an unstable channel.展开更多
Active mid-infrared(MIR)imagers capable of retrieving three-dimensional(3D)structure and reflectivity information are highly attractive in a wide range of biomedical and industrial applications.However,infrared 3D ima...Active mid-infrared(MIR)imagers capable of retrieving three-dimensional(3D)structure and reflectivity information are highly attractive in a wide range of biomedical and industrial applications.However,infrared 3D imaging at lowlight levels is still challenging due to the deficiency of sensitive and fast MiR sensors.Here we propose and implement a MiR time-of-flight imaging system that operates at single-photon sensitivity and femtosecond timing resolution.Specifically,back-scattered infrared photons from a scene are optically gated by delay-controlled ultrashort pump pulses through nonlinear frequency upconversion.The upconverted images with time stamps are then recorded by a silicon camera to facilitate the 3D reconstruction with high lateral and depth resolutions.Moreover,an effective numerical denoiser based on spatiotemporal correlation allows us to reveal the object profle and reflectivity under photon-starving conditions with a detected flux below 0.05 photons/pixel/second.The presented MIR 3D imager features high detection sensitivity,precise timing resolution,and wide-field operation,which may open new possibilities in life and material sciences.展开更多
.Laser-induced breakdown spectroscopy(LIBS)is a useful tool for determination of elements in solids,liquids,and gases.For nanosecond LIBS(ns-LIBS),the plasma shielding effect limits its reproducibility,repeatability,a....Laser-induced breakdown spectroscopy(LIBS)is a useful tool for determination of elements in solids,liquids,and gases.For nanosecond LIBS(ns-LIBS),the plasma shielding effect limits its reproducibility,repeatability,and signal-to-noise ratios.Although femtosecond laser filament induced breakdown spectroscopy(FIBS)has no plasma shielding effects,the power density clamping inside the filaments limits the measurement sensitivity.We propose and demonstrate plasma-grating-induced breakdown spectroscopy(GIBS).The technique relies on a plasma excitation source-a plasma grating generated by the interference of two noncollinear femtosecond filaments.We demonstrate that GIBS can overcome the limitations of standard techniques such as ns-LIBS and FIBS.Signal intensity enhancement with GIBS is observed to be greater than 3 times that of FIBS.The matrix effect is also significantly reduced with GIBS,by virtue of the high power and electron density of the plasma grating,demonstrating great potential for analyzing samples with complex matrix.展开更多
We have proposed and experimentally demonstrated a novel scheme for efficient mid-infrared difference-frequency generation based on passively synchronized fiber lasers. The adoption of coincident seeding pulses in the...We have proposed and experimentally demonstrated a novel scheme for efficient mid-infrared difference-frequency generation based on passively synchronized fiber lasers. The adoption of coincident seeding pulses in the nonlinear conversion process could substantially lower the pumping threshold for mid-infrared parametric emission. Consequently,a picosecond mid-infrared source at 3.1 μm was prepared with watt-level average power, and a maximum power conversion efficiency of 77% was realized from pump to down-converted light. Additionally, the long-term stability of generated power was manifested with a relative fluctuation as low as 0.17% over one hour. Thanks to the all-optical passive synchronization and all-polarization-maintaining fiber architecture, the implemented laser system was also featured with simplicity, compactness and robustness, which would favor subsequent applications beyond laboratory operation.展开更多
Optical detectors with single-photon sensitivity and large dynamic range would facilitate a variety of applications.Specifically,the capability of extending operation wavelengths into the mid-infrared region is highly...Optical detectors with single-photon sensitivity and large dynamic range would facilitate a variety of applications.Specifically,the capability of extending operation wavelengths into the mid-infrared region is highly attractive.Here we implement a mid-infrared frequency upconversion detector for counting and resolving photons at 3μm.Thanks to the spectrotemporal engineering of the involved optical fields,the mid-infrared photons could be spectrally translated into the visible band with a conversion efficiency of 80%.In combination with a silicon avalanche photodiode,we obtained unprecedented performance with a high overall detection efficiency of 37%and a low noise equivalent power of 1.8×10^(-17) W∕Hz1∕2.Furthermore,photon-number-resolving detection at mid-infrared wavelengths was demonstrated,for the first time to our knowledge,with a multipixel photon counter.The implemented upconversion detector exhibited a maximal resolving photon number up to 9 with a noise probability per pulse of 0.14%at the peak detection efficiency.The achieved photon counting and resolving performance might open up new possibilities in trace molecule spectroscopy,sensitive biochemical sensing,and free-space communications,among others.展开更多
The notion of topological phases extended to dynamical systems stimulates extensive studies,of which the characterization of nonequilibrium topological invariants is a central issue and usually necessitates the inform...The notion of topological phases extended to dynamical systems stimulates extensive studies,of which the characterization of nonequilibrium topological invariants is a central issue and usually necessitates the information of quantum dynamics in both the time and momentum dimensions.Here,we propose the topological holographic quench dynamics in synthetic dimension,and also show it provides a highly efficient scheme to characterize photonic topological phases.A pseudospin model is constructed with ring resonators in a synthetic lattice formed by frequencies of light,and the quench dynamics is induced by initializing a trivial state,which evolves under a topological Hamiltonian.Our key prediction is that the complete topological information of the Hamiltonian is encoded in quench dynamics solely in the time dimension,and is further mapped to lower-dimensional space,manifesting the holographic features of the dynamics.In particular,two fundamental time scales emerge in the dynamical evolution,with one mimicking the topological band on the momentum dimension and the other characterizing the residue time evolution of the state after the quench.For this,a universal duality between the quench dynamics and the equilibrium topological phase of the spin model is obtained in the time dimension by extracting information from the field evolution dynamics in modulated ring systems in simulations.This work also shows that the photonic synthetic frequency dimension provides an efficient and powerful way to explore the topological nonequilibrium dynamics.展开更多
基金Project supported by the Natural Science Foundation of Shandong Province,China(Grant No.ZR2020MA070).
文摘By using one-dimensional tight-binding model modified to include electron-electric field interaction and electron-electron interaction,we theoretically explore the polarization process of exciton and biexciton in cis-polyacetylene.The dynamical simulation is performed by adopting the non-adiabatic evolution approach.The results show that under the effect of moderate electric field,when the strength of electron-electron interaction is weak,the singlet exciton is stable but its polarization presents obvious oscillation.With the enhancement of interaction,it is dissociated into polaron pairs,the spin-flip of which can be observed through modulating the interaction strength.For the triplet exciton,the strong electron-electron interaction restrains its normal polarization,but it is still stable.In the case of biexciton,the strong electron-electron interaction not only dissociate it,but also flip its charge distribution.The yield of the possible states formed after the dissociation of exciton and biexciton is also calculated.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11621404,11561121003,11727812,61775059,12074122,62022033,and 11704123)Shanghai Rising-Star Program,the Sustainedly Supported Foundation by the National Key Laboratory of Science and Technology on Space Microwave(Grant No.HTKT2022KL504008)+1 种基金Shanghai Natural Science Foundation(Grant No.23ZR1419000)the National Key Laboratory Foundation of China(Grant No.6142411196307).
文摘Nyquist pulses have wide applications in many areas,from electronics to optics.Mode-locked lasers are ideal platforms to generate such pulses.However,how to generate high-quality Nyquist pulses in mode-locked lasers remains elusive.We address this problem by managing different physical effects in mode-locked fiber lasers through extensive numerical simulations.We find that net dispersion,linear loss,gain and filter shaping can affect the quality of Nyquist pulses significantly.We also demonstrate that Nyquist pulses experience similariton shaping due to the nonlinear attractor effect in the gain medium.Our work may contribute to the design of Nyquist pulse sources and enrich the understanding of pulse shaping dynamics in mode-locked lasers.
基金supported by the National Key Research and Development Program of China(Grant Nos.2017YFA0303700 and 2018YFA0306301)the National Natural Science Foundation of China(Grant Nos.11734011,12004245,and 62105154)+3 种基金the Foundation for Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01-ZX06)the Shandong Quancheng Scholarship(Grant No.00242019024)the China Postdoctoral Science Foundation(Grant No.2021M691601)the Natural Science Foundation of Jiangsu Province(Grant No.BK20210324)。
文摘Perfect vector beams are a class of special vector beams with invariant radius and intensity profiles under changing topological charges.However,with the limitation of current devices,the generation of these vector beams is limited in the visible and infrared wavebands.Herein,we generate perfect vector beams in the ultraviolet region assisted by nonlinear frequency conversion.Experimental and simulation results show that the radius of the generated ultraviolet perfect vector beams remains invariant and is thus independent of the topological charge.Furthermore,we measure the power of the generated ultraviolet perfect vector beams with the change of their topological charges.This study provides an alternative approach to generating perfect vector beams for ultraviolet wavebands and may promote their application to optical trapping and optical communication.
基金sponsored by Shanghai Rising-Star Program(22QC1401000)National Defense Administration of Science,Technology and Industry(HTKJ2021KL504014)+2 种基金National Key Research and Development Program(2018YFB0504400)National Natural Science Foundation ofChina(11621404,11727812,and 62035005)Shanghai Municipal Science and Technology Major Project(2019SHZDZX01-ZX05).
文摘Breakdown spectroscopy is a valuable tool for determining elements in solids,liquids,and gases.All materials in the breakdown region can be ionized and dissociated into highly excited fragments and emit characteristic fluorescence spectra.In this sense,the elemental composition of materials can be evaluated by detecting the fluorescence spectrum.This paper reviews the recent developments in laser-induced breakdown spectroscopy.The traditional laser-induced breakdown spectroscopy,filament-induced breakdown spectroscopy,plasma grating,and multidimensional plasma grating-induced breakdown spectroscopy are introduced.There are also some proposals for applications of plasma gratings,such as laser ablation,laser deposition,and laser catalysis of chemical reactions in conjunction with research on the properties of plasma gratings.
基金the funding from the National Natural Science Foundation of China(Grant nos.51802113 and 51802116)High Technology Research and Development Program of Shandong Province(Grant no.2018****0209)the Natural Science Foundation of Shandong Province(Grant nos.ZR2018BEM015 and ZR2019LLZ003).
文摘Recently,integrated photonics has attracted considerable interest owing to its wide application in optical communication and quantum technologies.Among the numerous photonic materials,lithium niobate film on insulator(LNOI)has become a promising photonic platform owing to its electro-optic and nonlinear optical properties along with ultralow-loss and high-confinement nanophotonic lithium niobate waveguides fabricated by the complementary metal-oxide-semiconductor(CMOS)-compatible microstructure engineering of LNOI.Furthermore,ferroelectric domain engineering in combination with nanophotonic waveguides on LNOI is gradually accelerating the development of integrated nonlinear photonics,which will play an important role in quantum technologies because of its ability to be integrated with the generation,processing,and auxiliary detection of the quantum states of light.Herein,we review the recent progress in CMOS-compatible microstructure engineering and domain engineering of LNOI for integrated lithium niobate photonics involving photonic modulation and nonlinear photonics.We believe that the great progress in integrated photonics on LNOI will lead to a new generation of techniques.Thus,there remains an urgent need for efficient methods for the preparation of LNOI that are suitable for large-scale and low-cost manufacturing of integrated photonic devices and systems.
基金supported by the National Key Research and Development Program (No.2018YFB0504400)National Natural Science Foundation of China (NSFC)(Nos.61875243and 11804100)+1 种基金Shanghai Municipal Science and Technology Major Project (No.2019SHZDZX01)Science and Technology Innovation Program of Basic Science Foundation of Shanghai (No.18JC1412000)。
文摘In this paper, we demonstrated a series of short-living mode-locking(ML) states(each lasting a few to a hundred microseconds) that happened before a fiber laser reached a steady ML state.With time-stretched dispersion Fourier transform spectroscopy, a rich diversity of transient multi-pulse dynamics were revealed spectrally and temporally.As a result, we found that the formation of the short-living ML states was related to abundant pump power, and their decaying evolution dynamics were possibly governed by gain depletion and recovery.Our results revealed unexpected transient lasing behaviors of a soliton laser and thus might be useful to understand the complex dynamics of mode-locked lasers.
基金supported in part by the National Natural Science Foundation of China(NSFC)(Nos.11734011,62022058,12074252,and 12004245)the National Key R&D Program of China(Nos.2017YFA0303701 and 2018YFA0306301)+2 种基金the Shanghai Municipal Science and Technology Major Project(No.2019SHZDZX01)the Shanghai Rising-Star Program(No.20QA1405400)the Shandong Quancheng Scholarship(No.00242019024)。
文摘Orbital angular momentum(OAM)is a fundamental physical characteristic to describe laser fields with a spiral phase structure.Vortex beams carrying OAMs have attracted more and more attention in recent years.However,the wavefront of OAM light would be destroyed when it passes through scattering media.Here,based on the feedback-based wavefront shaping method,we reconstitute OAM wavefronts behind strongly scattering media.The intensity of light with desired OAM states is enhanced to 150 times.This study provides a method to manipulate OAMs of scattered light and is of great significance for OAM optical communication and imaging to overcome complex environment interference.
基金the National Natural Science Foundation of China(91836303)the National Key R&D Program of China(2019YFA0308700)+1 种基金the Chinese Academy of Sciences,the Anhui Initiative in Quantum Information Technologies,the Natural Science Foundation of Shandong Province(ZR2020LLZ007)the ShanghaiMunicipal Science and Technology Major Project(2019SHZDZX01).
文摘In the quest to realize a scalable quantum network,semiconductor quantum dots(QDs)offer distinct advantages,including high single-photon efficiency and indistinguishability,high repetition rate(tens of gigahertz with Purcell enhancement),interconnectivity with spin qubits,and a scalable on-chip platform.However,in the past two decades,the visibility of quantum interference between independent QDs rarely went beyond the classical limit of 50%,and the distances were limited from a few meters to kilometers.Here,we report quantum interference between two single photons from independent QDs separated by a 302 km optical fiber.The single photons are generated from resonantly driven single QDs deterministically coupled to microcavities.Quantum frequency conversions are used to eliminate the QD inhomogeneity and shift the emission wavelength to the telecommunication band.The observed interference visibility is 0.670.02(0.930.04)without(with)temporal filtering.Feasible improvements can further extend the distance to∼600 km.Our work represents a key step to long-distance solid-state quantum networks.
基金This work was supported by the National Key R&D Program of China(No.2018YFA0306301)the National Natural Science Foundation of China(NSFC)(Nos.11734011,11764020,and 12104298)+1 种基金the China Postdoctoral Science Foundation(Nos.2020M681275 and 2021T140452)the Foundation for Shanghai Municipal Science and Technology Major Project(No.2019SHZDZX01-ZX06).
文摘Atherosclerotic cardio-cerebral vascular disease is the most common disease that threatens human health.Many researches indicated that oxidatively modified low-density lipoprotein[ox-LDL]is a key pathogenic factor of atherosclero-sis.Here,we report the change of the secondary structure of ox-LDL caused by photoirradiation in an optofluidic resonator.The content ratios of amphipathic o-helices and β-sheets of ox-LDL are changed under laser beam ilumination,resulting in an increasing binding rate of ox-LDL and ox-LDL antibodies.Our findings may provide a potential way for clinical athero-sclerosis treatment and prompt recovery rate of atherosclerotic cardio-cerebral vascular disease by optical technology and immunotherapy.
基金Ministry of Science and Technology of China through the National Key Research and Development Program of China(2020YFA0309701)National Natural Science Foundation of China(12104184,12174215,11974204,12147107)+3 种基金Shandong Provincial Natural Science Foundation(ZR2021LLZ007)Key R&D Plan of Shandong Province(2021ZDPT01)Open Research Fund Program of the State Key Laboratory of Low-Dimensional Quantum Physics(KF202110)Leading Talents of Quancheng Industry。
文摘Measurement-device-independent quantum key distribution(MDI-QKD)protocol can remove all the loopholes of the detection devices and,thus,has attracted much attention.Based on the technique of single-photon interference,we propose a modified MDI-QKD protocol with phase post-selection.We prove the security of the announcement of the private phases in the X basis and show how to apply the phase post-selection method to the double-scanning four-intensity MDI-QKD protocol.The numerical results show that the phase postselection method can significantly improve the key rates at all distances.In the double-scanning method,two parameters need to be scanned in the calculation of the final key rate,and the global parameter optimization is pretty time-consuming.We propose an accelerated method that can greatly reduce the running time of the global parameter optimization program.This makes the method practically useful in an unstable channel.
基金supported by the National Natural Science Foundation of China(Nos.62175064,62235019,62035005)Shanghai Pilot Program for Basic Research(TQ20220104)+1 种基金Shanghai Municipal Science and Technology Major Project(2019SHZDZX01)Fundamental Research Funds for the Central Universities.
文摘Active mid-infrared(MIR)imagers capable of retrieving three-dimensional(3D)structure and reflectivity information are highly attractive in a wide range of biomedical and industrial applications.However,infrared 3D imaging at lowlight levels is still challenging due to the deficiency of sensitive and fast MiR sensors.Here we propose and implement a MiR time-of-flight imaging system that operates at single-photon sensitivity and femtosecond timing resolution.Specifically,back-scattered infrared photons from a scene are optically gated by delay-controlled ultrashort pump pulses through nonlinear frequency upconversion.The upconverted images with time stamps are then recorded by a silicon camera to facilitate the 3D reconstruction with high lateral and depth resolutions.Moreover,an effective numerical denoiser based on spatiotemporal correlation allows us to reveal the object profle and reflectivity under photon-starving conditions with a detected flux below 0.05 photons/pixel/second.The presented MIR 3D imager features high detection sensitivity,precise timing resolution,and wide-field operation,which may open new possibilities in life and material sciences.
基金We acknowledge the support fromthe National Key Research and Development Program(No.2018YFB0407100)the National Natural Science Foundation of China(No.11621404)the Key Project of Shanghai Education Commission(No.2017-01-07-00-05-E00021).
文摘.Laser-induced breakdown spectroscopy(LIBS)is a useful tool for determination of elements in solids,liquids,and gases.For nanosecond LIBS(ns-LIBS),the plasma shielding effect limits its reproducibility,repeatability,and signal-to-noise ratios.Although femtosecond laser filament induced breakdown spectroscopy(FIBS)has no plasma shielding effects,the power density clamping inside the filaments limits the measurement sensitivity.We propose and demonstrate plasma-grating-induced breakdown spectroscopy(GIBS).The technique relies on a plasma excitation source-a plasma grating generated by the interference of two noncollinear femtosecond filaments.We demonstrate that GIBS can overcome the limitations of standard techniques such as ns-LIBS and FIBS.Signal intensity enhancement with GIBS is observed to be greater than 3 times that of FIBS.The matrix effect is also significantly reduced with GIBS,by virtue of the high power and electron density of the plasma grating,demonstrating great potential for analyzing samples with complex matrix.
基金supported in part by the National Key Research and Development Program(No.2018YFB0407100)Science and Technology Innovation Program of Basic Science Foundation of Shanghai(No.18JC1412000)+1 种基金Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learning,National Natural Science Foundation of China(Nos.11621404 and 11727812)Shanghai Municipal Science and Technology Major Project(No.2019SHZDZX01)。
文摘We have proposed and experimentally demonstrated a novel scheme for efficient mid-infrared difference-frequency generation based on passively synchronized fiber lasers. The adoption of coincident seeding pulses in the nonlinear conversion process could substantially lower the pumping threshold for mid-infrared parametric emission. Consequently,a picosecond mid-infrared source at 3.1 μm was prepared with watt-level average power, and a maximum power conversion efficiency of 77% was realized from pump to down-converted light. Additionally, the long-term stability of generated power was manifested with a relative fluctuation as low as 0.17% over one hour. Thanks to the all-optical passive synchronization and all-polarization-maintaining fiber architecture, the implemented laser system was also featured with simplicity, compactness and robustness, which would favor subsequent applications beyond laboratory operation.
基金National Key Research and Development Program of China(2018YFB0407100)Science and Technology Innovation Program of Basic Science Foundation of Shanghai(18JC1412000)+2 种基金Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher LearningNational Natural Science Foundation of China(11621404,11727812)Shanghai Municipal Science and Technology Major Project(2019SHZDZX01)。
文摘Optical detectors with single-photon sensitivity and large dynamic range would facilitate a variety of applications.Specifically,the capability of extending operation wavelengths into the mid-infrared region is highly attractive.Here we implement a mid-infrared frequency upconversion detector for counting and resolving photons at 3μm.Thanks to the spectrotemporal engineering of the involved optical fields,the mid-infrared photons could be spectrally translated into the visible band with a conversion efficiency of 80%.In combination with a silicon avalanche photodiode,we obtained unprecedented performance with a high overall detection efficiency of 37%and a low noise equivalent power of 1.8×10^(-17) W∕Hz1∕2.Furthermore,photon-number-resolving detection at mid-infrared wavelengths was demonstrated,for the first time to our knowledge,with a multipixel photon counter.The implemented upconversion detector exhibited a maximal resolving photon number up to 9 with a noise probability per pulse of 0.14%at the peak detection efficiency.The achieved photon counting and resolving performance might open up new possibilities in trace molecule spectroscopy,sensitive biochemical sensing,and free-space communications,among others.
基金the National Natural Science Foundation of China(11822410,12034013,11734009,and 11974245)the National Key R&D Program of China(2017YFA0303701 and 2019YFA0705000)+10 种基金the Shanghai Municipal Science and Technology Major Project(2019SHZDZX01)the Program of Shanghai Academic Research Leader(20XD1424200)the Natural Science Foundation of Shanghai(19ZR1475700)the Strategic Priority Research Program of Chinese Academy of Sciences(XDB16030300)the Key Research Program of Frontier Sciences of Chinese Academy of Sciences(QYZDJ-SSW-SLH010)the Youth Innovation Promotion Association of Chinese Academy of Sciences(2018284)NSF(ECCS-1509268,and CMMI-1826078)AFOSR(FA9550-20-1-0366)partially supported by the Fundamental Research Funds for the Central Universitiesthe support from the Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learningthe support from Shandong Quancheng Scholarship(00242019024)。
基金This paper was supported by the National Natural Science Foundation of China(11974245,11825401,and 11761161003)National Key R&D Program of China(2017YFA0303701)+3 种基金Shanghai Municipal Science and Technology Major Project(2019SHZDZX01)Natural Science Foundation of Shanghai(19ZR1475700)by the Open Project of Shenzhen Institute of Quantum Science and Engineering(Grant No.SIQSE202003)L.Y.acknowledges support from the Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learning.X.C.also acknowledges the support from Shandong Quancheng Scholarship(00242019024).
文摘The notion of topological phases extended to dynamical systems stimulates extensive studies,of which the characterization of nonequilibrium topological invariants is a central issue and usually necessitates the information of quantum dynamics in both the time and momentum dimensions.Here,we propose the topological holographic quench dynamics in synthetic dimension,and also show it provides a highly efficient scheme to characterize photonic topological phases.A pseudospin model is constructed with ring resonators in a synthetic lattice formed by frequencies of light,and the quench dynamics is induced by initializing a trivial state,which evolves under a topological Hamiltonian.Our key prediction is that the complete topological information of the Hamiltonian is encoded in quench dynamics solely in the time dimension,and is further mapped to lower-dimensional space,manifesting the holographic features of the dynamics.In particular,two fundamental time scales emerge in the dynamical evolution,with one mimicking the topological band on the momentum dimension and the other characterizing the residue time evolution of the state after the quench.For this,a universal duality between the quench dynamics and the equilibrium topological phase of the spin model is obtained in the time dimension by extracting information from the field evolution dynamics in modulated ring systems in simulations.This work also shows that the photonic synthetic frequency dimension provides an efficient and powerful way to explore the topological nonequilibrium dynamics.
