Entanglement serves as a fundamental resource for quantum information protocols,and hyperentanglement has received an increasing amount of attention for its high-capacity characteristic.Increasing the scale of hyperen...Entanglement serves as a fundamental resource for quantum information protocols,and hyperentanglement has received an increasing amount of attention for its high-capacity characteristic.Increasing the scale of hyperentanglement,i.e.,the number of modes in a hyperentangled system,is crucial for enhancing its capability in quantum information processing.Here,we demonstrate the generation of large-scale continuous-variable(CV)hyperentanglement in three degrees of freedom(DOFs),including azimuthal and radial indices of Laguerre–Gaussian(LG)modes and frequency.In our experiment,216 pairs of hyperentangled modes are deterministically generated from the four-wave mixing process in an atomic vapor.In addition,we show that the entanglement between coherent LG superposition modes denoted by both azimuthal and radial quantum numbers can also be generated from this system.Such large-scale CV hyperentanglement in three DOFs presents an efficient scheme to significantly increase the information capacity of the CV system.Our results provide a new platform for studying CV quantum information and open the avenue for constructing high-capacity parallel and multiple-DOF CV quantum information protocols.展开更多
We experimentally demonstrate a low-noise phase-sensitive amplifier(PSA)scheme that is able to amplify bright entangled beams at a high level intensity gain of up to 4.4.Moreover,we demonstrate that the PSA scheme int...We experimentally demonstrate a low-noise phase-sensitive amplifier(PSA)scheme that is able to amplify bright entangled beams at a high level intensity gain of up to 4.4.Moreover,we demonstrate that the PSA scheme introduces much less uncorrelated extra noise to the entangled state than the phase-insensitive amplifier scheme with the same intensity gain.This PSA scheme has potential applications for quantum communication in continuous variable regimes.展开更多
The reliable detection of entanglement plays a crucial role in the construction of quantum networks.The conventional entanglement witness(EW)method has high requirements for measurement device and relies on reliable i...The reliable detection of entanglement plays a crucial role in the construction of quantum networks.The conventional entanglement witness(EW)method has high requirements for measurement device and relies on reliable implementation of the measurement.With unreliable measurement device,EW process can be easily attacked by eavesdroppers,which can lead to incorrect entanglement detection results.Therefore,a feasible and secure measurement device independent entanglement witness(MDIEW)method is desired for constructing quantum networks.Here,we detect the continuous variable entanglement by a MDIEW in a quantum network.It is demonstrated that the conventional EW method can be affected when the local oscillator intensity is changed,while the MDIEW method can detect entanglement between users without being affected.Our results provide a trustworthy method to detect entanglement,which is an important step for constructing secure quantum networks.展开更多
We experimentally generate 9 sets of orbital angular momentum(OAM)multiplexed four-beam quadrature squeezing by utilizing four-wave mixing processes in a rubidium vapor.The degree of four-beam quadrature squeezing dec...We experimentally generate 9 sets of orbital angular momentum(OAM)multiplexed four-beam quadrature squeezing by utilizing four-wave mixing processes in a rubidium vapor.The degree of four-beam quadrature squeezing decreases with the increase of topological charge|l|.In addition,we investigate the four-beam quadrature squeezing with OAM superposition modes.Our results provide an efficient way to generate OAM multiplexed multi-beam quadrature squeezing and may find potential applications in multi-parameter estimation.展开更多
Quantum state sharing,an important protocol in quantum information,can enable secure state distribution and reconstruction when part of the information is lost.In(k,n)threshold quantum state sharing,the secret state i...Quantum state sharing,an important protocol in quantum information,can enable secure state distribution and reconstruction when part of the information is lost.In(k,n)threshold quantum state sharing,the secret state is encoded into n shares and then distributed to n players.The secret state can be reconstructed by any k players(k>n∕2),while the rest of the players get nothing.In the continuous variable regime,the implementation of quantum state sharing needs the feedforward technique,which involves opticelectro and electro-optic conversions.These conversions limit the bandwidth of the quantum state sharing.Here,to avoid the optic-electro and electro-optic conversions,we experimentally demonstrate(2,3)threshold deterministic all-optical quantum state sharing.A low-noise phase-insensitive amplifier based on the four-wave mixing process is utilized to replace the feedforward technique.We experimentally demonstrate that any two of three players can cooperate to implement the reconstruction of the secret state,while the rest of the players cannot get any information.Our results provide an all-optical platform to implement arbitrary(k,n)threshold deterministic all-optical quantum state sharing and pave the way to construct the all-optical broadband quantum network.展开更多
Quantum stochastic phase estimation has many applications in the precise measurement of various physical parameters.Similar to the estimation of a constant phase,there is a standard quantum limit for stochastic phase ...Quantum stochastic phase estimation has many applications in the precise measurement of various physical parameters.Similar to the estimation of a constant phase,there is a standard quantum limit for stochastic phase estimation,which can be obtained with the Mach-Zehnder interferometer and coherent input state.Recently,it has been shown that the stochastic standard quantum limit can be surpassed with nonclassical resources such as squcezed light.However,practical methods to achieve quantum enhancement in the stochastic phase estimation remain largely unexplored.Here we propose a method utilizing the SU(1,1)interferometer and coherent input states to cstimate a stochastic optical phase.As an example,we investigate the Ornstcin-Uhlenback stochastic phase.We analyze the performance of this method for three key estimation problems:prediction,tracking,and smoothing.The results show significant reduction of the mean square error compared with the Mach-Zehnder interferometer under the same photon number flux inside the interferometers.In particular,we show that the method with the SU(1,1)interferometer can achieve fundamental quantum scaling,achieve stochastic Heisenberg scalinga and surpass the precision of the canonical measurement.展开更多
The four-wave mixing process in atomic ensembles has many important applications in quantum information.We review recent progress on the generation of optical quantum states from the four-wave mixing process in hot at...The four-wave mixing process in atomic ensembles has many important applications in quantum information.We review recent progress on the generation of optical quantum states from the four-wave mixing process in hot atomic ensembles,including the production of two-beam,multi-beam,and multiplexed quantum correlated or entangled states.We also review the applications of these optical quantum states in implementing quantum information protocols,constructing SU(1,1)quantum interferometers,and realizing quantum plasmonic sensing.These applications indicate that the four-wave mixing process in hot atomic ensembles is a promising platform for quantum information processing,especially for implementing alloptical quantum information protocols,constructing SU(1,1)interferometers,and realizing quantum sensing.展开更多
Quantum squeezing is an important quantum resource for quantum metrology as it can improve the measurement precision.By enhancing the quantum squeezing level,the measurement precision can be further improved.Here,we e...Quantum squeezing is an important quantum resource for quantum metrology as it can improve the measurement precision.By enhancing the quantum squeezing level,the measurement precision can be further improved.Here,we experimentally implement quantum squeezing enhancement based on phase-sensitive cascaded four-wave mixing(CFWM)processes.The intensitydifference squeezing(IDS)between the two outputs of the phase-sensitive CFWM processes is enhanced to about 7.42 dB compared with IDS generated by the single four-wave mixing(FWM)process(about 3.31 or 4.01 dB).Such enhancement is enabled by both the intrinsic interference nature of phase-sensitive CFWM processes and the contribution of more gain from the two FWM processes.In addition,we measure IDS levels generated by phase-sensitive CFWM processes at different internalphase-locking points,which shows that the internal phase plays an important role in IDS enhancement.Our scheme provides a new method for improving the degree of IDS and may find potential applications in enhancing the measurement precision in quantum metrology.展开更多
基金the Innovation Program of Shanghai Municipal Education Commission(Grant No.2021-01-07-00-08-E00100)the National Natural Science Foundation of China(Grant Nos.11874155,91436211,11374104,and 12174110)+7 种基金the Basic Research Project of Shanghai Science and Technology Commission(Grant No.20JC1416100)the Natural Science Foundation of Shanghai(17ZR1442900)the Minhang Leading Talents(Grant No.201971)the Program of Scientific and Technological Innovation of Shanghai(Grant No.17JC1400401)the Shanghai Sailing Program(Grant No.21YF1410800)the National Basic Research Program of China(Grant No.2016YFA0302103)the Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01)the 111 Project(Grant No.B12024).
文摘Entanglement serves as a fundamental resource for quantum information protocols,and hyperentanglement has received an increasing amount of attention for its high-capacity characteristic.Increasing the scale of hyperentanglement,i.e.,the number of modes in a hyperentangled system,is crucial for enhancing its capability in quantum information processing.Here,we demonstrate the generation of large-scale continuous-variable(CV)hyperentanglement in three degrees of freedom(DOFs),including azimuthal and radial indices of Laguerre–Gaussian(LG)modes and frequency.In our experiment,216 pairs of hyperentangled modes are deterministically generated from the four-wave mixing process in an atomic vapor.In addition,we show that the entanglement between coherent LG superposition modes denoted by both azimuthal and radial quantum numbers can also be generated from this system.Such large-scale CV hyperentanglement in three DOFs presents an efficient scheme to significantly increase the information capacity of the CV system.Our results provide a new platform for studying CV quantum information and open the avenue for constructing high-capacity parallel and multiple-DOF CV quantum information protocols.
基金Supported by the Innovation Program of Shanghai Municipal Education Commission(Grant No.2021-01-07-00-08-E00100)the National Natural Science Foundation of China(Grant Nos.11874155,91436211,11374104)+6 种基金the Basic Research Project of Shanghai Science and Technology Commission(20JC1416100)the Natural Science Foundation of Shanghai(Grant No.17ZR1442900)Minhang Leading Talents(Grant No.201971),the Program of Scientific and Technological Innovation of Shanghai(Grant No.17JC1400401)the Shanghai Sailing Program(Grant No.21YF1410800)the National Basic Research Program of China(Grant No.2016YFA0302103)the Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01)the 111 Project(Grant No.B12024).
文摘We experimentally demonstrate a low-noise phase-sensitive amplifier(PSA)scheme that is able to amplify bright entangled beams at a high level intensity gain of up to 4.4.Moreover,we demonstrate that the PSA scheme introduces much less uncorrelated extra noise to the entangled state than the phase-insensitive amplifier scheme with the same intensity gain.This PSA scheme has potential applications for quantum communication in continuous variable regimes.
基金funded by the National Natural Science Foundation of China(NSFC,No.12225404,No.12434014,No.11874155,No.91436211,No.11374104,No.12174110,No.12574390,and No.12474357)Innovation Program for Quantum Science and Technology(No.2024ZD0302402)+10 种基金Innovation Program of Shanghai Municipal Education Commission(No.2021-01-07-00-08-E00100)Program of Shanghai Academic Research Leader(No.22XD1400700)Basic Research Project in Quantum Science of Shanghai Action Plan for Science Technology and Innovation(No.24LZ1400700)Fundamental Research Funds for the Central UniversitiesBasic Research Project of Shanghai Science and Technology Commission(No.20JC1416100)Natural Science Foundation of Shanghai(No.17ZR1442900,No.24ZR1418700)Minhang Leading Talents(No.201971)Shanghai Sailing Program(No.21YF1410800)Natural Science Foundation of Chongqing(No.CSTB2022NSCQ-MSX0893)Shanghai Municipal Science and Technology Major Project(No.2019SHZDZX01)and the 111 project(B12024).
文摘The reliable detection of entanglement plays a crucial role in the construction of quantum networks.The conventional entanglement witness(EW)method has high requirements for measurement device and relies on reliable implementation of the measurement.With unreliable measurement device,EW process can be easily attacked by eavesdroppers,which can lead to incorrect entanglement detection results.Therefore,a feasible and secure measurement device independent entanglement witness(MDIEW)method is desired for constructing quantum networks.Here,we detect the continuous variable entanglement by a MDIEW in a quantum network.It is demonstrated that the conventional EW method can be affected when the local oscillator intensity is changed,while the MDIEW method can detect entanglement between users without being affected.Our results provide a trustworthy method to detect entanglement,which is an important step for constructing secure quantum networks.
基金funded by the National Natural Science Foun-dation of China(11874155,91436211,11374104,12174110)Innovation Program of Shanghai Municipal Education Commission(2021-01-07-00-08-E00100)+7 种基金Program of Shanghai Academic Research Leader(22XD1400700)Basic Research Project of Shanghai Science and Technology Commission(20JC1416100)Natural Science Foundation of Shanghai(17ZR1442900)Minhang Leading Talents(201971)Shanghai Sailing Program(21YF1410800)Natural Science Foundation of Chongqing(CSTB2022NSCQ-MSX0893)Shanghai Municipal Science and Technology Major Project(2019SHZDZX01)the 111 project(B12024).
文摘We experimentally generate 9 sets of orbital angular momentum(OAM)multiplexed four-beam quadrature squeezing by utilizing four-wave mixing processes in a rubidium vapor.The degree of four-beam quadrature squeezing decreases with the increase of topological charge|l|.In addition,we investigate the four-beam quadrature squeezing with OAM superposition modes.Our results provide an efficient way to generate OAM multiplexed multi-beam quadrature squeezing and may find potential applications in multi-parameter estimation.
基金the National Natural Science Foundation of China(Grant Nos.12225404,11874155,91436211,11374104,and 12174110)the Innovation Program of Shanghai Municipal Education Commission(Grant No.2021-01-07-00-08-E00100)+7 种基金the Program of Shanghai Academic Research Leader(Grant No.22XD1400700)the Basic Research Project of Shanghai Science and Technology Commission(Grant No.20JC1416100)the Natural Science Foundation of Shanghai(Grant No.17ZR1442900)the Minhang Leading Talents(Grant No.201971)the Shanghai Sailing Program(Grant No.21YF1410800)the Natural Science Foundation of Chongqing(Grant No.CSTB2022NSCQ-MSX0893)the Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01)the 111 Project(Grant No.B12024).
文摘Quantum state sharing,an important protocol in quantum information,can enable secure state distribution and reconstruction when part of the information is lost.In(k,n)threshold quantum state sharing,the secret state is encoded into n shares and then distributed to n players.The secret state can be reconstructed by any k players(k>n∕2),while the rest of the players get nothing.In the continuous variable regime,the implementation of quantum state sharing needs the feedforward technique,which involves opticelectro and electro-optic conversions.These conversions limit the bandwidth of the quantum state sharing.Here,to avoid the optic-electro and electro-optic conversions,we experimentally demonstrate(2,3)threshold deterministic all-optical quantum state sharing.A low-noise phase-insensitive amplifier based on the four-wave mixing process is utilized to replace the feedforward technique.We experimentally demonstrate that any two of three players can cooperate to implement the reconstruction of the secret state,while the rest of the players cannot get any information.Our results provide an all-optical platform to implement arbitrary(k,n)threshold deterministic all-optical quantum state sharing and pave the way to construct the all-optical broadband quantum network.
基金National Key Research and Development Program of China(2017YFA0303703,2019YFA0308704)National Natural Science Foundation of China(11664017,11590052,11574155,51490711,61973077,91436211,91836303)+3 种基金Fundamental Research Funds for the Central Universitics(No.020214380068)Natural Science Foundjarion of Shanghai(17ZR1442900)Nanjing Universiry Innovation and Creative Program for PhD candidatc(2016017)Basic Research Project of Shanghai Science and Technology Commission(20JC1416100).
文摘Quantum stochastic phase estimation has many applications in the precise measurement of various physical parameters.Similar to the estimation of a constant phase,there is a standard quantum limit for stochastic phase estimation,which can be obtained with the Mach-Zehnder interferometer and coherent input state.Recently,it has been shown that the stochastic standard quantum limit can be surpassed with nonclassical resources such as squcezed light.However,practical methods to achieve quantum enhancement in the stochastic phase estimation remain largely unexplored.Here we propose a method utilizing the SU(1,1)interferometer and coherent input states to cstimate a stochastic optical phase.As an example,we investigate the Ornstcin-Uhlenback stochastic phase.We analyze the performance of this method for three key estimation problems:prediction,tracking,and smoothing.The results show significant reduction of the mean square error compared with the Mach-Zehnder interferometer under the same photon number flux inside the interferometers.In particular,we show that the method with the SU(1,1)interferometer can achieve fundamental quantum scaling,achieve stochastic Heisenberg scalinga and surpass the precision of the canonical measurement.
基金the Innovation Program of Shanghai Municipal Education Commission(2021-01-07-00-08-E00100)National Natural Science Foundation of China(11874155,91436211,11374104,12174110)+8 种基金Basic Research Project of Shanghai Science and Technology Commission(20JC1416100)Natural Science Foundation of Shanghai(17ZR1442900)Minhang Leading Talents(201971)Program of Scientific and Technological Innovation of Shanghai(17JC1400401)Shanghai Sailing Program(21YF1410800)China Post-doctoral Science Foundation(2020M681224)National Basic Research Program of China(2016YFA0302103)Shanghai Municipal Science and Technology Major Project(2019SHZDZX01)111 Project(B12024).
文摘The four-wave mixing process in atomic ensembles has many important applications in quantum information.We review recent progress on the generation of optical quantum states from the four-wave mixing process in hot atomic ensembles,including the production of two-beam,multi-beam,and multiplexed quantum correlated or entangled states.We also review the applications of these optical quantum states in implementing quantum information protocols,constructing SU(1,1)quantum interferometers,and realizing quantum plasmonic sensing.These applications indicate that the four-wave mixing process in hot atomic ensembles is a promising platform for quantum information processing,especially for implementing alloptical quantum information protocols,constructing SU(1,1)interferometers,and realizing quantum sensing.
基金supported by the National Natural Science Foundation of China(Grant Nos.12225404,11874155,91436211,11374104,and 12174110)the Innovation Program of Shanghai Municipal Education Commission(Grant No.2021-01-07-00-08-E00100)+7 种基金the Program of Shanghai Academic Research Leader(Grant No.22XD1400700)the Basic Research Project of Shanghai Science and Technology Commission(Grant No.20JC1416100)the Natural Science Foundation of Shanghai(Grant No.17ZR1442900)the Minhang Leading Talents(Grant No.201971)the Shanghai Sailing Program(Grant No.21YF1410800)the Natural Science Foundation of Chongqing(Grant No.CSTB2022NSCQ-MSX0893)the Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01)the 111 Project(Grant No.B12024).
文摘Quantum squeezing is an important quantum resource for quantum metrology as it can improve the measurement precision.By enhancing the quantum squeezing level,the measurement precision can be further improved.Here,we experimentally implement quantum squeezing enhancement based on phase-sensitive cascaded four-wave mixing(CFWM)processes.The intensitydifference squeezing(IDS)between the two outputs of the phase-sensitive CFWM processes is enhanced to about 7.42 dB compared with IDS generated by the single four-wave mixing(FWM)process(about 3.31 or 4.01 dB).Such enhancement is enabled by both the intrinsic interference nature of phase-sensitive CFWM processes and the contribution of more gain from the two FWM processes.In addition,we measure IDS levels generated by phase-sensitive CFWM processes at different internalphase-locking points,which shows that the internal phase plays an important role in IDS enhancement.Our scheme provides a new method for improving the degree of IDS and may find potential applications in enhancing the measurement precision in quantum metrology.
