Quantum dialogue(QD)enables two communication parties to directly exchange secret messages simultaneously.In conventional QD protocols,photons need to transmit in the quantum channel for two rounds.In this paper,we pr...Quantum dialogue(QD)enables two communication parties to directly exchange secret messages simultaneously.In conventional QD protocols,photons need to transmit in the quantum channel for two rounds.In this paper,we propose a one-step QD protocol based on the hyperentanglement.With the help of the non-local hyperentanglement-assisted Bell state measurement(BSM),the photons only need to transmit in the quantum channel once.We prove that our one-step QD protocol is secure in theory and numerically simulate its secret message capacity under practical experimental condition.Compared with previous QD protocols,the one-step QD protocol can effectively simplify the experiment operations and reduce the message loss caused by the photon transmission loss.Meanwhile,the non-local hyperentanglement-assisted BSM has a success probability of 100%and is feasible with linear optical elements.Moreover,combined with the hyperentanglement heralded amplification and purification,our protocol is possible to realize long-distance one-step QD.展开更多
A quantum steering ellipsoid(QSE)is a visual characterization for bipartite qubit systems,and it is also a novel avenue for describing and detecting quantum correlations.Herein,by using a QSE,we visualize and witness ...A quantum steering ellipsoid(QSE)is a visual characterization for bipartite qubit systems,and it is also a novel avenue for describing and detecting quantum correlations.Herein,by using a QSE,we visualize and witness the first-order coherence(FOC),Bell nonlocality(BN)and purity under non-inertial frames.Also,the collective influences of the depolarizing channel and the non-coherence-generating channel(NCGC)on the FOC,BN and purity are investigated in the QSE formalism.The results reveal that the distance from the center of the QSE to the center of the Bloch sphere visualizes the FOC of a bipartite system,the lengths of the QSE semiaxis visualize the BN,and the QSE's shape and position dominate the purity of the system.One can capture the FOC,BN and purity via the shape and position of the QSE in the non-inertial frame.The depolarizing channel(the NCGC)gives rise to the shrinking and degradation(the periodical oscillation)of the QSE.One can use these traits to visually characterize and detect the FOC,BN and purity under the influence of external noise.Of particular note is that the condition for the QSE to achieve the center of the Bloch sphere cannot be influenced by the depolarizing channel and the NCGC.The characterization shows that the conditions for the disappearance of the FOC are invariant under the additional influences of the depolarizing channel and NCGC.展开更多
The past two decades have witnessed a surge of interest in exploring correlation and coherence measures to investigate quantum phase transitions(QPTs). Here, motivated by the continued push along this direction, we pr...The past two decades have witnessed a surge of interest in exploring correlation and coherence measures to investigate quantum phase transitions(QPTs). Here, motivated by the continued push along this direction, we propose a measure which is built upon the so-called degree of coherence, and advocate using the susceptibility of our measure to detect QPTs. We show that our measure can capture both the notions of coherence and correlations exhibited in bipartite states and therefore represents a hybrid of these two notions. Through examining the XXZ model and the Kitaev honeycomb model, we demonstrate that our measure is favorable for detecting QPTs in comparison to many previous proposals.展开更多
Quantum secure direct communication(QSDC)can transmit the secret message directly.Single-photon-based QSDC protocol requires the active modulation of the quantum state of the source,potentially introducing various sid...Quantum secure direct communication(QSDC)can transmit the secret message directly.Single-photon-based QSDC protocol requires the active modulation of the quantum state of the source,potentially introducing various side-channel vulnerabilities.In this paper,we propose a passive-state preparation QSDC protocol.By utilizing a passive-state preparation method,we remove the need for active modulation,thus eliminating the side-channel risks associated with the source encoder.To evaluate the performance of the protocol,we develop a system model and improve the decoy state method.Through parameter optimization,we identify the optimal secrecy message capacity for various communication distances and compare it with active modulation QSDC.At a communication distance of 10(15)km,the secrecy message capacity of passive-state preparation QSDC reaches3.894×10^(-4)(3.715×10^(-5))bit/pulse,achieving 95.3%(91.5%)of the active case’s performance.Meanwhile,we consider the resource consumption and optimize the secrecy message transmission rate of passive-state preparation QSDC.Using a coherent light source with a frequency of 10^(6)Hz,at communication distances of 5,10,and 15 km,the secrecy message transmission rates for passive-state preparation QSDC reach 2.370×10^(2),4.218×10,and 2.504 bit/s,respectively.展开更多
Quantum secure direct communication(QSDC)can directly transmit secret messages through quantum channel without keys.Device-independent(DI)QSDC guarantees the message security relying only on the observation of the Bel...Quantum secure direct communication(QSDC)can directly transmit secret messages through quantum channel without keys.Device-independent(DI)QSDC guarantees the message security relying only on the observation of the Bell-inequality violation,but not on any detailed description or trust of the devices'inner workings.Compared with conventional QSDC,DI-QSDC has relatively low secret message capacity.To increase DI-QSDC's secret messages capacity,we propose a high-capacity DI-QSDC protocol based on the hyper-encoding technique.The total message leakage rate of our DI-QSDC protocol only relies on the most robust degree of freedom.We provide the numerical simulation of its secret message capacity altered with the communication distance.Our work serves as an important step toward thefurther development of DI-QSDC systems.展开更多
Hyperentanglement, the simultaneous entanglement in more than one degree of freedom(DOF), plays an important role in quantum communication and quantum information processing for it can effectively increase the channel...Hyperentanglement, the simultaneous entanglement in more than one degree of freedom(DOF), plays an important role in quantum communication and quantum information processing for it can effectively increase the channel capacity. Existing hyperentanglement sources mainly focus on the generation of the hyperentanglement in two DOFs. In this paper, we design the generation protocols for three kinds of hyperentanglement encoded in three DOFs with the practical coherent pulses sources, including the polarization-frequency-space hyperentanglement, the polarization-frequency-time-bin hyperentanglement, and the polarizationspace-time-bin hyperentanglement. These protocols exploit the spontaneous parametric down-conversion(SPDC) process and the Sagnac interferometer. The three protocols are all based on feasible experimental condition and may have potential applications in future hyperentanglement-based quantum communication and quantum information processing protocols.展开更多
Quantum secure direct communication(QSDC)can transmit secret messages without keys,making it an important branch of quantum communication.We present a hybrid entanglement-based quantum secure direct communication(HE-Q...Quantum secure direct communication(QSDC)can transmit secret messages without keys,making it an important branch of quantum communication.We present a hybrid entanglement-based quantum secure direct communication(HE-QSDC)protocol with simple linear optical elements,combining the benefits of both continuous variables(CV)and discrete variables(DV)encoding.We analyze the security and find that the QSDC protocol has a positive security capacity when the bit error rate is less than 0.073.Compared with previous DV QSDC protocols,our protocol has higher communication efficiency due to performing nearly deterministic Bell-state measurement.On the other hand,compared with CV QSDC protocol,this protocol has higher fidelity with largeα.Based on these advantages,our protocol may provide an alternative approach to realize secure communication.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12175106 and 92365110).
文摘Quantum dialogue(QD)enables two communication parties to directly exchange secret messages simultaneously.In conventional QD protocols,photons need to transmit in the quantum channel for two rounds.In this paper,we propose a one-step QD protocol based on the hyperentanglement.With the help of the non-local hyperentanglement-assisted Bell state measurement(BSM),the photons only need to transmit in the quantum channel once.We prove that our one-step QD protocol is secure in theory and numerically simulate its secret message capacity under practical experimental condition.Compared with previous QD protocols,the one-step QD protocol can effectively simplify the experiment operations and reduce the message loss caused by the photon transmission loss.Meanwhile,the non-local hyperentanglement-assisted BSM has a success probability of 100%and is feasible with linear optical elements.Moreover,combined with the hyperentanglement heralded amplification and purification,our protocol is possible to realize long-distance one-step QD.
基金Project supported by the National Natural Science Foundation of China(Grant No.12175001)the Natural Science Research Key Project of the Education Department of Anhui Province of China(Grant No.KJ2021A0943)+3 种基金the Research Start-up Funding Project of High Level Talent of West Anhui University(Grant No.WGKQ2021048)an Open Project of the Key Laboratory of Functional Materials and Devices for Informatics of Anhui Higher Education Institutes(Grant No.FMDI202106)the University Synergy Innovation Program of Anhui Province(Grant No.GXXT-2021-026)the Anhui Provincial Natural Science Foundation(Grant Nos.2108085MA18 and 2008085MA20)。
文摘A quantum steering ellipsoid(QSE)is a visual characterization for bipartite qubit systems,and it is also a novel avenue for describing and detecting quantum correlations.Herein,by using a QSE,we visualize and witness the first-order coherence(FOC),Bell nonlocality(BN)and purity under non-inertial frames.Also,the collective influences of the depolarizing channel and the non-coherence-generating channel(NCGC)on the FOC,BN and purity are investigated in the QSE formalism.The results reveal that the distance from the center of the QSE to the center of the Bloch sphere visualizes the FOC of a bipartite system,the lengths of the QSE semiaxis visualize the BN,and the QSE's shape and position dominate the purity of the system.One can capture the FOC,BN and purity via the shape and position of the QSE in the non-inertial frame.The depolarizing channel(the NCGC)gives rise to the shrinking and degradation(the periodical oscillation)of the QSE.One can use these traits to visually characterize and detect the FOC,BN and purity under the influence of external noise.Of particular note is that the condition for the QSE to achieve the center of the Bloch sphere cannot be influenced by the depolarizing channel and the NCGC.The characterization shows that the conditions for the disappearance of the FOC are invariant under the additional influences of the depolarizing channel and NCGC.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11775129, and 12174224)。
文摘The past two decades have witnessed a surge of interest in exploring correlation and coherence measures to investigate quantum phase transitions(QPTs). Here, motivated by the continued push along this direction, we propose a measure which is built upon the so-called degree of coherence, and advocate using the susceptibility of our measure to detect QPTs. We show that our measure can capture both the notions of coherence and correlations exhibited in bipartite states and therefore represents a hybrid of these two notions. Through examining the XXZ model and the Kitaev honeycomb model, we demonstrate that our measure is favorable for detecting QPTs in comparison to many previous proposals.
基金supported by the National Natural Science Foundation of China(Grant Nos.12175106,12405016,and 92365110)the Natural Science Foundation of Jiangsu Province of China(Grant Nos.BK20240611and BK20240612)the Key R&D Program of Guangdong Province(Grant No.2018B030325002)。
文摘Quantum secure direct communication(QSDC)can transmit the secret message directly.Single-photon-based QSDC protocol requires the active modulation of the quantum state of the source,potentially introducing various side-channel vulnerabilities.In this paper,we propose a passive-state preparation QSDC protocol.By utilizing a passive-state preparation method,we remove the need for active modulation,thus eliminating the side-channel risks associated with the source encoder.To evaluate the performance of the protocol,we develop a system model and improve the decoy state method.Through parameter optimization,we identify the optimal secrecy message capacity for various communication distances and compare it with active modulation QSDC.At a communication distance of 10(15)km,the secrecy message capacity of passive-state preparation QSDC reaches3.894×10^(-4)(3.715×10^(-5))bit/pulse,achieving 95.3%(91.5%)of the active case’s performance.Meanwhile,we consider the resource consumption and optimize the secrecy message transmission rate of passive-state preparation QSDC.Using a coherent light source with a frequency of 10^(6)Hz,at communication distances of 5,10,and 15 km,the secrecy message transmission rates for passive-state preparation QSDC reach 2.370×10^(2),4.218×10,and 2.504 bit/s,respectively.
基金the National Natural Science Foundation of China(11974189,12175106 and 92365110)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX22-0900).
文摘Quantum secure direct communication(QSDC)can directly transmit secret messages through quantum channel without keys.Device-independent(DI)QSDC guarantees the message security relying only on the observation of the Bell-inequality violation,but not on any detailed description or trust of the devices'inner workings.Compared with conventional QSDC,DI-QSDC has relatively low secret message capacity.To increase DI-QSDC's secret messages capacity,we propose a high-capacity DI-QSDC protocol based on the hyper-encoding technique.The total message leakage rate of our DI-QSDC protocol only relies on the most robust degree of freedom.We provide the numerical simulation of its secret message capacity altered with the communication distance.Our work serves as an important step toward thefurther development of DI-QSDC systems.
基金supported by the National Natural Science Foundation of China(Grant Nos.11974189,12175106,and 92365110)Postgraduate Research&Practice Innovation Program of Jiangsu Province(Grant No.KYCX23-1027)。
文摘Hyperentanglement, the simultaneous entanglement in more than one degree of freedom(DOF), plays an important role in quantum communication and quantum information processing for it can effectively increase the channel capacity. Existing hyperentanglement sources mainly focus on the generation of the hyperentanglement in two DOFs. In this paper, we design the generation protocols for three kinds of hyperentanglement encoded in three DOFs with the practical coherent pulses sources, including the polarization-frequency-space hyperentanglement, the polarization-frequency-time-bin hyperentanglement, and the polarizationspace-time-bin hyperentanglement. These protocols exploit the spontaneous parametric down-conversion(SPDC) process and the Sagnac interferometer. The three protocols are all based on feasible experimental condition and may have potential applications in future hyperentanglement-based quantum communication and quantum information processing protocols.
基金supported by the National Natural Science Foundation of China(Grant Nos.11974189,12175106 and 92365110)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(Grant No.KYCX23-1027)the Key R&D Program of Guangdong Province(Grant No.2018B030325002).
文摘Quantum secure direct communication(QSDC)can transmit secret messages without keys,making it an important branch of quantum communication.We present a hybrid entanglement-based quantum secure direct communication(HE-QSDC)protocol with simple linear optical elements,combining the benefits of both continuous variables(CV)and discrete variables(DV)encoding.We analyze the security and find that the QSDC protocol has a positive security capacity when the bit error rate is less than 0.073.Compared with previous DV QSDC protocols,our protocol has higher communication efficiency due to performing nearly deterministic Bell-state measurement.On the other hand,compared with CV QSDC protocol,this protocol has higher fidelity with largeα.Based on these advantages,our protocol may provide an alternative approach to realize secure communication.
