Cavity magnomechanics,exhibiting remarkable experimental tunability,rich magnonic nonlinearities,and compatibility with various quantum systems,has witnessed considerable advances in recent years.However,the potential...Cavity magnomechanics,exhibiting remarkable experimental tunability,rich magnonic nonlinearities,and compatibility with various quantum systems,has witnessed considerable advances in recent years.However,the potential benefits of using cavity magnomechanical(CMM)systems in further improving the performance of quantum-enhanced sensing for weak forces remain largely unexplored.Here we show that,by squeezing the magnons,the performance of a quantum CMM sensor can be significantly enhanced beyond the standard quantum limit(SQL).We find that,for comparable parameters,two orders of magnitude enhancement in the force sensitivity can be achieved in comparison with the case without magnon squeezing.Moreover,we obtain the optimal parameter regimes of homodyne angle for minimizing the added quantum noise.Our findings provide a promising approach for highly tunable and compatible quantum force sensing using hybrid CMM devices,with potential applications ranging from quantum precision measurements to quantum information processing.展开更多
This work presents a theoretical simulation of the infrared spectra of strong hydrogen bond in alpha-phase 2-pyridone dimers, as well as in their deuterium derivatives at room temperature. The theory takes into accoun...This work presents a theoretical simulation of the infrared spectra of strong hydrogen bond in alpha-phase 2-pyridone dimers, as well as in their deuterium derivatives at room temperature. The theory takes into account an adiabatic anharmonic coupling between the high-frequency N-H(D) stretching and the low-frequency intermolecular N...O stretching modes by considering that the effective angular frequency of the fast mode N-H(D) is assumed to be strongly dependent on the slow mode stretching coordinate N...O, the intrinsic anharmonicity of the low-frequency N...O mode through a Morse potential, Davydov coupling triggered by resonance exchange between the excited states of the fast modes of the two hydrogen bonds involved in the cyclic dimer, multiple Fermi resonances between the N-H(D) stretching and the overtone of the N-H(D) bending vibrations and the direct and indirect damping of the fast stretching modes of the hydrogen bonds and of the bending modes. The IR spectral density is computed within the linear response theory by Fourier transform of the autocorrelation function of the transition dipole moment operator of the N-H(D) bond. The theoretical line shapes of the υN-H(D) band of alpha-phase 2-pyridone dimers are compared to the experimental ones. The effect of deuteration is successfully reproduced.展开更多
The Loschmidt echo is a useful diagnostic for the perfection of quantum time-reversal process and the sensitivity of quantum evolution to small perturbations. The main challenge for measuring the Loschmidt echo is the...The Loschmidt echo is a useful diagnostic for the perfection of quantum time-reversal process and the sensitivity of quantum evolution to small perturbations. The main challenge for measuring the Loschmidt echo is the time reversal of a quantum evolution. In this work, we demonstrate the measurement of the Loschmidt echo in a superconducting 10-qubit system using Floquet engineering and discuss the imperfection of an initial Bell-state recovery arising from the next-nearestneighbor(NNN) coupling present in the qubit device. Our results show that the Loschmidt echo is very sensitive to small perturbations during quantum-state evolution, in contrast to the quantities like qubit population that is often considered in the time-reversal experiment. These properties may be employed for the investigation of multiqubit system concerning many-body decoherence and entanglement, etc., especially when devices with reduced or vanishing NNN coupling are used.展开更多
Quantum magnonics has recently attracted considerable interest not only in fundamental physics but also in applications,ranging from quantum information processing to quantum metrology[1].A unique merit of magnons,the...Quantum magnonics has recently attracted considerable interest not only in fundamental physics but also in applications,ranging from quantum information processing to quantum metrology[1].A unique merit of magnons,the quasiparticles or quantized unit of magnetic excitations in solids,is their ability to be effectively coupled with almost all different quantum information carriers,such as optical photons,mechanical phonons,superconducting qubits,and solid-state spins,which are otherwise difficult to be efficiently integrated together.展开更多
The recently developed hybrid magnonics provides new opportunities for advances in both the study of magnetism and the development of quantum information processing.However,engineering coherent quantum state transfer ...The recently developed hybrid magnonics provides new opportunities for advances in both the study of magnetism and the development of quantum information processing.However,engineering coherent quantum state transfer between magnons and specific information carriers,in particular,mechanical oscillators and solid-state spins,remains challenging due to the intrinsically weak interactions and the frequency mismatch between different components.Here,we show how to strongly couple the magnon modes in a nanomagnet to the quantized mechanical motion(phonons)of a micromechanical cantilever in a hybrid tripartite system.The coherent and enhanced magnon-phonon coupling is engineered by introducing the quantum parametric amplification of the mechanical motion.With experimentally feasible parameters,we show that the mechanical parametric drive can be adjusted to drive the system into the strong-coupling regime and even the ultrastrong-coupling regime.Furthermore,we show the coherent state transfer between the nanomagnet and a nitrogen-vacancy center in the dispersive-coupling regime,with the magnon-spin interaction mediated by the virtually-excited squeezed phonons.The amplified mechanical noise can hardly interrupt the coherent dynamics of the system even for low mechanical quality factors,which removes the requirement of applying additional engineered-reservoir techniques.Our work opens up prospects for developing novel quantum transducers,quantum memories and high-precision measurements.展开更多
Simulation of open quantum dynamics for various Hamiltonians and spectral densities are ubiquitous for studying various quantum systems.On a quantum computer,only log2N qubits are required for the simulation of an N-d...Simulation of open quantum dynamics for various Hamiltonians and spectral densities are ubiquitous for studying various quantum systems.On a quantum computer,only log2N qubits are required for the simulation of an N-dimensional quantum system,hence simulation in a quantum computer can greatly reduce the computational complexity compared with classical methods.Recently,a quantum simulation approach was proposed for studying photosynthetic light harvesting[npj Quantum Inf.4,52(2018)].In this paper,we apply the approach to simulate the open quantum dynamics of various photosynthetic systems.We show that for Drude—Lorentz spectral density,the dimerized geometries with strong couplings within the donor and acceptor clusters respectively exhibit significantly improved efficiency.We also demonstrate that the overall energy transfer can be optimized when the energy gap between the donor and acceptor clusters matches the optimum of the spectral density.The effects of different types of baths,e.g.,Ohmic,sub-Ohmic,and super-Ohmic spectral densities are also studied.The present investigations demonstrate that the proposed approach is universal for simulating the exact quantum dynamics of photosynthetic systems.展开更多
Micro-LEDs are one of the most promising candidates for next-generation displays,yet they are inconvenienced by the efficiency reduction induced by the sidewall defects when pursuing further scaled-down device dimensi...Micro-LEDs are one of the most promising candidates for next-generation displays,yet they are inconvenienced by the efficiency reduction induced by the sidewall defects when pursuing further scaled-down device dimensions.We have systematically investigated both the size and temporal dependence of micro-LEDs.Micro-LED arrays with a mesa size ranging from 7 to 100μm were prepared for display purposes.The luminance and external quantum efficiency(EQE)were measured and discussed.Surprisingly,micro-LED arrays with a smaller mesa size exhibit a higher EQE under 100 ns pulse duration operation when compared with longer pulse duration operations.Under certain short-pulsed excitation,a 7×7μm^(2)micro-LED array even exhibits a>20%higher EQE as compared to the direct current(DC)or the long duration pulse operation condition.We thus concluded that the notorious efficiency reduction induced by sidewall defects in small-sized micro-LED arrays could be significantly reduced by applying short-pulse voltages.展开更多
Noether’s theorem is one of the fundamental laws in physics,relating the symmetry of a physical system to its constant of motion and conservation law.On the other hand,there exist a variety of non-Hermitian parity-ti...Noether’s theorem is one of the fundamental laws in physics,relating the symmetry of a physical system to its constant of motion and conservation law.On the other hand,there exist a variety of non-Hermitian parity-time(PT)-symmetric systems,which exhibit novel quantum properties and have attracted increasing interest.In this work,we extend Noether’s theorem to a class of significant PT-symmetry systems for which the eigenvalues of the PT-symmetry Hamiltonian HPTchange from purely real numbers to purely imaginary numbers,and introduce a generalized expectation value of an operator based on biorthogonal quantum mechanics.We find that the generalized expectation value of a time-independent operator is a constant of motion when the operator presents a standard symmetry in the PT-symmetry unbroken regime,or a chiral symmetry in the PT-symmetry broken regime.In addition,we experimentally investigate the extended Noether’s theorem in PT-symmetry single-qubit and two-qubit systems using an optical setup.Our experiment demonstrates the existence of the constant of motion and reveals how this constant of motion can be used to judge whether the PT-symmetry of a system is broken.Furthermore,a novel phenomenon of masking quantum information is first observed in a PT-symmetry two-qubit system.This study not only contributes to full understanding of the relation between symmetry and conservation law in PT-symmetry physics,but also has potential applications in quantum information theory and quantum communication protocols.展开更多
Schrödinger cat states,consisting of superpositions of macroscopically distinct states,provide key resources for a large number of emerging quantum technologies in quantum information processing.Here we propose h...Schrödinger cat states,consisting of superpositions of macroscopically distinct states,provide key resources for a large number of emerging quantum technologies in quantum information processing.Here we propose how to generate and manipulate mechanical and optical Schrödinger cat states with distinguishable superposition components by exploiting the unique properties of cavity optomechanical systems based on Bose-Einstein condensate.Specifically,we show that in comparison with its solid-state counterparts,almost a 3 order of magnitude enhancement in the size of the mechanical Schrödinger cat state could be achieved,characterizing a much smaller overlap between its two superposed coherent-state components.By exploiting this generated cat state,we further show how to engineer the quadrature squeezing of the mechanical mode.Besides,we also provide an efficient method to create multicomponent optical Schrödinger cat states in our proposed scheme.Our work opens up a new way to achieve nonclassical states of massive objects,facilitating the development of fault-tolerant quantum processors and sensors.展开更多
We propose how to achieve quantum nonreciprocity via unconventional photon blockade(UPB) in a compound device consisting of an optical harmonic resonator and a spinning optomechanical resonator. We show that, even wit...We propose how to achieve quantum nonreciprocity via unconventional photon blockade(UPB) in a compound device consisting of an optical harmonic resonator and a spinning optomechanical resonator. We show that, even with very weak single-photon nonlinearity, nonreciprocal UPB can emerge in this system, i.e., strong photon antibunching can emerge only by driving the device from one side but not from the other side. This nonreciprocity results from the Fizeau drag, leading to different splitting of the resonance frequencies for the optical counter-circulating modes. Such quantum nonreciprocal devices can be particularly useful in achieving backaction-free quantum sensing or chiral photonic communications.展开更多
Three fiber Bragg grating （FBG） sensors systems for hydrogen detection are presented using the classic Pd （palladium） coating technique （500nm） as the hydrogen sensitive film and titanium （Ti） as the adhesive ...Three fiber Bragg grating （FBG） sensors systems for hydrogen detection are presented using the classic Pd （palladium） coating technique （500nm） as the hydrogen sensitive film and titanium （Ti） as the adhesive layer with the etched cladding. These systems are compared and used for disaster environment prevention in hydrogen leakage environment where higher values than the normal are presented which increase the risk of explosion. With these systems, 0. 1% - 4% of the hydrogen volume concentration range in the volume ratio was detected and monitored experimentally in the test room with the very sensitive and stable value which reached 60pm/1% HE. In addition, a fast response time, about 6 s, was obtained with an advanced sensor.展开更多
Photodynamic therapy (PDT) is a very effective treatment for port wine stains (PWS). To guide and assess PDT treatment, a handheld optical coherence tomography (OCT) probe was designed for real-time imaging of the PWS...Photodynamic therapy (PDT) is a very effective treatment for port wine stains (PWS). To guide and assess PDT treatment, a handheld optical coherence tomography (OCT) probe was designed for real-time imaging of the PWS patient. The system uses a light source with a center wavelength of 1310 nm, -3 dB bandwidth of 90 nm and an optical power of 9 mW. The system also has a spatial resolution of 8 μm (lateral) × 7 μm (axial), an imaging rate of 4 frames per second, and a 102 dB sensitivity. We then demonstrate that the OCT imaging system can clearly distinguish between normal and PWS tissues. Therefore, the system can provide valuable guidance for PDT treatment.展开更多
The high efficiency hydrogen fiber Bragg grating （FBG） sensor is presented. The sensitive film was a new alliance of palladium-silver （Pd-Ag）. In addition, the titanium （Ti） layer was used as the adhesive layer....The high efficiency hydrogen fiber Bragg grating （FBG） sensor is presented. The sensitive film was a new alliance of palladium-silver （Pd-Ag）. In addition, the titanium （Ti） layer was used as the adhesive layer. The presented sensor showed the resolution of more than 60pm/1%H2, and a fast response time of4s - 5s was guaranteed in the 0.1%H2 - 4%H2 range. Moreover, the life time of the sensor was investigated. The obtained results showed that the sensor had an enhanced life time. Furthermore, the sensor was applied in the propulsion system fuel tank model of the aerospace vehicle. The obtained results indicated that it is a prevention system against the disaster aerospace due to hydrogen leakage.展开更多
We propose a protocol for detecting a single atom in a cavity with the help of the χ^((2)) nonlinear medium.When the χ^((2)) nonlinear medium is driven by an external laser field,the cavity mode will be squeezed,and...We propose a protocol for detecting a single atom in a cavity with the help of the χ^((2)) nonlinear medium.When the χ^((2)) nonlinear medium is driven by an external laser field,the cavity mode will be squeezed,and thus one can obtain an exponentially enhanced light-matter coupling.Such a strong coupling between the atom and the cavity field can significantly change the output photon flux,the quantum fluctuations,the quantum statistical property,and the photon number distributions of the cavity field.This provides practical strategies to determine the presence or absence of an atom in a cavity.The proposed protocol exhibits some advantages,such as controllable squeezing strength and exponential increase of atom-cavity coupling strength,which make the experimental phenomenon more obvious.We hope that this protocol can supplement the existing intracavity single-atom detection protocols and provide a promise for quantum sensing in different quantum systems.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.11935006)supported by the National Natural Science Foundation of China(Grant No.12205054)+7 种基金the Science and Technology Innovation Program of Hunan Province(Grant No.2020RC4047)National Key R&D Program of China(Grant No.2024YFE0102400)Hunan Provincial Major Scitech Program(Grant No.2023ZJ1010)Ph.D.Research Foundation(BSJJ202122)supported by the Japan Society for the Promotion of Science(JSPS)Postdoctoral Fellowships for Research in Japan(No.P22018)Nippon Telegraph and Telephone Corporation(NTT)Research,the Japan Science and Technology Agency(JST)(via the Quantum Leap Flagship Program(Q-LEAP),and the Moonshot R&D(Grant No.JPMJMS2061))the Asian Office of Aerospace Research and Development(AOARD)(Grant No.FA2386-20-1-4069)the Office of Naval Research(ONR)Global(Grant No.N62909-23-1-2074)。
文摘Cavity magnomechanics,exhibiting remarkable experimental tunability,rich magnonic nonlinearities,and compatibility with various quantum systems,has witnessed considerable advances in recent years.However,the potential benefits of using cavity magnomechanical(CMM)systems in further improving the performance of quantum-enhanced sensing for weak forces remain largely unexplored.Here we show that,by squeezing the magnons,the performance of a quantum CMM sensor can be significantly enhanced beyond the standard quantum limit(SQL).We find that,for comparable parameters,two orders of magnitude enhancement in the force sensitivity can be achieved in comparison with the case without magnon squeezing.Moreover,we obtain the optimal parameter regimes of homodyne angle for minimizing the added quantum noise.Our findings provide a promising approach for highly tunable and compatible quantum force sensing using hybrid CMM devices,with potential applications ranging from quantum precision measurements to quantum information processing.
文摘This work presents a theoretical simulation of the infrared spectra of strong hydrogen bond in alpha-phase 2-pyridone dimers, as well as in their deuterium derivatives at room temperature. The theory takes into account an adiabatic anharmonic coupling between the high-frequency N-H(D) stretching and the low-frequency intermolecular N...O stretching modes by considering that the effective angular frequency of the fast mode N-H(D) is assumed to be strongly dependent on the slow mode stretching coordinate N...O, the intrinsic anharmonicity of the low-frequency N...O mode through a Morse potential, Davydov coupling triggered by resonance exchange between the excited states of the fast modes of the two hydrogen bonds involved in the cyclic dimer, multiple Fermi resonances between the N-H(D) stretching and the overtone of the N-H(D) bending vibrations and the direct and indirect damping of the fast stretching modes of the hydrogen bonds and of the bending modes. The IR spectral density is computed within the linear response theory by Fourier transform of the autocorrelation function of the transition dipole moment operator of the N-H(D) bond. The theoretical line shapes of the υN-H(D) band of alpha-phase 2-pyridone dimers are compared to the experimental ones. The effect of deuteration is successfully reproduced.
基金supported in part by the Key-Area Research and Development Program of Guang-Dong Province, China (Grant No. 2018B030326001)the National Key R&D Program of China (Grant No. 2017YFA0304300)+5 种基金supported by the Japan Society for the Promotion of Science (JSPS) (Postdoctoral Fellowship via Grant No. P19326, and KAKENHI via Grant No. JP19F19326)support from the Natural Science Foundation of Beijing, China (Grant No. Z190012)the National Natural Science Foundation of of China (Grant No. 11890704)support from the National Natural Science Foundation of China (Grant No. T2121001)Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDB28000000)Beijing Natural Science Foundation, China (Grant No. Z200009)。
文摘The Loschmidt echo is a useful diagnostic for the perfection of quantum time-reversal process and the sensitivity of quantum evolution to small perturbations. The main challenge for measuring the Loschmidt echo is the time reversal of a quantum evolution. In this work, we demonstrate the measurement of the Loschmidt echo in a superconducting 10-qubit system using Floquet engineering and discuss the imperfection of an initial Bell-state recovery arising from the next-nearestneighbor(NNN) coupling present in the qubit device. Our results show that the Loschmidt echo is very sensitive to small perturbations during quantum-state evolution, in contrast to the quantities like qubit population that is often considered in the time-reversal experiment. These properties may be employed for the investigation of multiqubit system concerning many-body decoherence and entanglement, etc., especially when devices with reduced or vanishing NNN coupling are used.
文摘Quantum magnonics has recently attracted considerable interest not only in fundamental physics but also in applications,ranging from quantum information processing to quantum metrology[1].A unique merit of magnons,the quasiparticles or quantized unit of magnetic excitations in solids,is their ability to be effectively coupled with almost all different quantum information carriers,such as optical photons,mechanical phonons,superconducting qubits,and solid-state spins,which are otherwise difficult to be efficiently integrated together.
基金supported by the National Natural Science Foundation of China(Grant Nos.12205256,12304407,11935006,11774086,122471051217050862)+3 种基金the Henan Provincial Science and Technology Research Project(Grant Nos.232102221001,and 232102210175)the HNQSTIT project(Grant No.2022112)the Fundamental Research Funds for the Central Universities(Grant No.2023FRFK06012)the China Postdoctoral Science Foundation(Grant No.2023TQ0310)。
文摘The recently developed hybrid magnonics provides new opportunities for advances in both the study of magnetism and the development of quantum information processing.However,engineering coherent quantum state transfer between magnons and specific information carriers,in particular,mechanical oscillators and solid-state spins,remains challenging due to the intrinsically weak interactions and the frequency mismatch between different components.Here,we show how to strongly couple the magnon modes in a nanomagnet to the quantized mechanical motion(phonons)of a micromechanical cantilever in a hybrid tripartite system.The coherent and enhanced magnon-phonon coupling is engineered by introducing the quantum parametric amplification of the mechanical motion.With experimentally feasible parameters,we show that the mechanical parametric drive can be adjusted to drive the system into the strong-coupling regime and even the ultrastrong-coupling regime.Furthermore,we show the coherent state transfer between the nanomagnet and a nitrogen-vacancy center in the dispersive-coupling regime,with the magnon-spin interaction mediated by the virtually-excited squeezed phonons.The amplified mechanical noise can hardly interrupt the coherent dynamics of the system even for low mechanical quality factors,which removes the requirement of applying additional engineered-reservoir techniques.Our work opens up prospects for developing novel quantum transducers,quantum memories and high-precision measurements.
基金This work was supported by the National Natural Science Foundation of China under Grant Nos.11674033,11474026,and 11505007Beijing Natural Science Foundation under Grant No.1202017N.L.acknowledges partial support from JST PRESTO through Grant No.JPMJPR18GC.
文摘Simulation of open quantum dynamics for various Hamiltonians and spectral densities are ubiquitous for studying various quantum systems.On a quantum computer,only log2N qubits are required for the simulation of an N-dimensional quantum system,hence simulation in a quantum computer can greatly reduce the computational complexity compared with classical methods.Recently,a quantum simulation approach was proposed for studying photosynthetic light harvesting[npj Quantum Inf.4,52(2018)].In this paper,we apply the approach to simulate the open quantum dynamics of various photosynthetic systems.We show that for Drude—Lorentz spectral density,the dimerized geometries with strong couplings within the donor and acceptor clusters respectively exhibit significantly improved efficiency.We also demonstrate that the overall energy transfer can be optimized when the energy gap between the donor and acceptor clusters matches the optimum of the spectral density.The effects of different types of baths,e.g.,Ohmic,sub-Ohmic,and super-Ohmic spectral densities are also studied.The present investigations demonstrate that the proposed approach is universal for simulating the exact quantum dynamics of photosynthetic systems.
基金Fujian Provincial Projects(2021HZ0114,2021J01583,2021L3004)Fujian Science Technology Innovation Laboratory for Optoelectronic Information of China(2020ZZ110,2021ZZ122)National Key Research and Development Program of China(2021YFB3600104)。
文摘Micro-LEDs are one of the most promising candidates for next-generation displays,yet they are inconvenienced by the efficiency reduction induced by the sidewall defects when pursuing further scaled-down device dimensions.We have systematically investigated both the size and temporal dependence of micro-LEDs.Micro-LED arrays with a mesa size ranging from 7 to 100μm were prepared for display purposes.The luminance and external quantum efficiency(EQE)were measured and discussed.Surprisingly,micro-LED arrays with a smaller mesa size exhibit a higher EQE under 100 ns pulse duration operation when compared with longer pulse duration operations.Under certain short-pulsed excitation,a 7×7μm^(2)micro-LED array even exhibits a>20%higher EQE as compared to the direct current(DC)or the long duration pulse operation condition.We thus concluded that the notorious efficiency reduction induced by sidewall defects in small-sized micro-LED arrays could be significantly reduced by applying short-pulse voltages.
基金supported by the National Natural Science Foundation of China(Grant Nos.12264040,12204311,11804228,11865013,and U21A20436)the Jiangxi Natural Science Foundation(Grant Nos.20212BAB211018,20192ACBL20051)+8 种基金the Project of Jiangxi Province Higher Educational Science and Technology Program(Grant Nos.GJJ190891,and GJJ211735)the Key-Area Research and Development Program of Guangdong Province(Grant No.2018B03-0326001)supported in part by the Nippon Telegraph and Telephone(NTT)Corporation Researchthe Japan Science and Technology(JST)Agency[via the Quantum Leap Flagship Program(Q-LEAP)Moonshot R&D Grant Number JPMJMS2061]the Japan Society for the Promotion of Science(JSPS)[via the Grants-in-Aid for Scientific Research(KAKENHI)Grant No.JP20H00134]the Army Research Office(ARO)(Grant No.W911NF-18-1-0358)the Asian Office of Aerospace Research and Development(AOARD)(Grant No.FA2386-20-1-4069)the Foundational Questions Institute Fund(FQXi)(Grant No.FQXi-IAF19-06)。
文摘Noether’s theorem is one of the fundamental laws in physics,relating the symmetry of a physical system to its constant of motion and conservation law.On the other hand,there exist a variety of non-Hermitian parity-time(PT)-symmetric systems,which exhibit novel quantum properties and have attracted increasing interest.In this work,we extend Noether’s theorem to a class of significant PT-symmetry systems for which the eigenvalues of the PT-symmetry Hamiltonian HPTchange from purely real numbers to purely imaginary numbers,and introduce a generalized expectation value of an operator based on biorthogonal quantum mechanics.We find that the generalized expectation value of a time-independent operator is a constant of motion when the operator presents a standard symmetry in the PT-symmetry unbroken regime,or a chiral symmetry in the PT-symmetry broken regime.In addition,we experimentally investigate the extended Noether’s theorem in PT-symmetry single-qubit and two-qubit systems using an optical setup.Our experiment demonstrates the existence of the constant of motion and reveals how this constant of motion can be used to judge whether the PT-symmetry of a system is broken.Furthermore,a novel phenomenon of masking quantum information is first observed in a PT-symmetry two-qubit system.This study not only contributes to full understanding of the relation between symmetry and conservation law in PT-symmetry physics,but also has potential applications in quantum information theory and quantum communication protocols.
基金supported by the National Natural Science Foundation of China(NSFC)(11935006 and 11774086)the Science and Technology Innovation Program of Hunan Province(2020RC4047)+6 种基金L.-M.K.was supported by the NSFC(1217050862,11935006 and 11775075)X.-W.X.was supported by the NSFC(12064010)Natural Science Foundation of Hunan Province of China(2021JJ20036)Y.-F.J.was supported by the NSFC(12147156)the China Postdoctoral Science Foundation(2021M701176)the Science and Technology Innovation Program of Hunan Province(2021RC2078)B.J.L.was supported by Postgraduate Scientific Research Innovation Project of Hunan Province(CX20210471).
文摘Schrödinger cat states,consisting of superpositions of macroscopically distinct states,provide key resources for a large number of emerging quantum technologies in quantum information processing.Here we propose how to generate and manipulate mechanical and optical Schrödinger cat states with distinguishable superposition components by exploiting the unique properties of cavity optomechanical systems based on Bose-Einstein condensate.Specifically,we show that in comparison with its solid-state counterparts,almost a 3 order of magnitude enhancement in the size of the mechanical Schrödinger cat state could be achieved,characterizing a much smaller overlap between its two superposed coherent-state components.By exploiting this generated cat state,we further show how to engineer the quadrature squeezing of the mechanical mode.Besides,we also provide an efficient method to create multicomponent optical Schrödinger cat states in our proposed scheme.Our work opens up a new way to achieve nonclassical states of massive objects,facilitating the development of fault-tolerant quantum processors and sensors.
基金National Natural Science Foundation of China(NSFC)(11474087,11774086)
文摘We propose how to achieve quantum nonreciprocity via unconventional photon blockade(UPB) in a compound device consisting of an optical harmonic resonator and a spinning optomechanical resonator. We show that, even with very weak single-photon nonlinearity, nonreciprocal UPB can emerge in this system, i.e., strong photon antibunching can emerge only by driving the device from one side but not from the other side. This nonreciprocity results from the Fizeau drag, leading to different splitting of the resonance frequencies for the optical counter-circulating modes. Such quantum nonreciprocal devices can be particularly useful in achieving backaction-free quantum sensing or chiral photonic communications.
文摘Three fiber Bragg grating （FBG） sensors systems for hydrogen detection are presented using the classic Pd （palladium） coating technique （500nm） as the hydrogen sensitive film and titanium （Ti） as the adhesive layer with the etched cladding. These systems are compared and used for disaster environment prevention in hydrogen leakage environment where higher values than the normal are presented which increase the risk of explosion. With these systems, 0. 1% - 4% of the hydrogen volume concentration range in the volume ratio was detected and monitored experimentally in the test room with the very sensitive and stable value which reached 60pm/1% HE. In addition, a fast response time, about 6 s, was obtained with an advanced sensor.
基金supported in part by the National High-Tech Research and Development Program of China (2006AA02Z472)National Basic Research Program of China (001CB510307 and 2009CB929400)+1 种基金National Natural Science Foundation of China (90508001, 10676014 and 10574081)Tsinghua University Initiative Scientific Research Program
文摘Photodynamic therapy (PDT) is a very effective treatment for port wine stains (PWS). To guide and assess PDT treatment, a handheld optical coherence tomography (OCT) probe was designed for real-time imaging of the PWS patient. The system uses a light source with a center wavelength of 1310 nm, -3 dB bandwidth of 90 nm and an optical power of 9 mW. The system also has a spatial resolution of 8 μm (lateral) × 7 μm (axial), an imaging rate of 4 frames per second, and a 102 dB sensitivity. We then demonstrate that the OCT imaging system can clearly distinguish between normal and PWS tissues. Therefore, the system can provide valuable guidance for PDT treatment.
文摘The high efficiency hydrogen fiber Bragg grating （FBG） sensor is presented. The sensitive film was a new alliance of palladium-silver （Pd-Ag）. In addition, the titanium （Ti） layer was used as the adhesive layer. The presented sensor showed the resolution of more than 60pm/1%H2, and a fast response time of4s - 5s was guaranteed in the 0.1%H2 - 4%H2 range. Moreover, the life time of the sensor was investigated. The obtained results showed that the sensor had an enhanced life time. Furthermore, the sensor was applied in the propulsion system fuel tank model of the aerospace vehicle. The obtained results indicated that it is a prevention system against the disaster aerospace due to hydrogen leakage.
基金This work was supported by the National Natural Science Foundation of China under Grant Nos.11575045,11874114,and 11674060the Natural Science Funds for Distinguished Young Scholar of Fujian Province under Grant 2020J06011Project from Fuzhou University under Grant JG202001-2.Y.-H.C.is supported by the Japan Society for the Promotion of Science(JSPS)KAKENHI Grant No.JP19F19028.
文摘We propose a protocol for detecting a single atom in a cavity with the help of the χ^((2)) nonlinear medium.When the χ^((2)) nonlinear medium is driven by an external laser field,the cavity mode will be squeezed,and thus one can obtain an exponentially enhanced light-matter coupling.Such a strong coupling between the atom and the cavity field can significantly change the output photon flux,the quantum fluctuations,the quantum statistical property,and the photon number distributions of the cavity field.This provides practical strategies to determine the presence or absence of an atom in a cavity.The proposed protocol exhibits some advantages,such as controllable squeezing strength and exponential increase of atom-cavity coupling strength,which make the experimental phenomenon more obvious.We hope that this protocol can supplement the existing intracavity single-atom detection protocols and provide a promise for quantum sensing in different quantum systems.
