Theoretical Research On Measurement-device-independent Quantum Secure Direct Communication

Quantum information is a new interdisciplinary subject developed in recent decades,which is an emerging research field that combines quantum physics with computer science and information science.It mainly includes quantum communication and quantum computing.In recent years,quantum information has made great breakthroughs in both theory and experiment.Quantum communication transmits classical or quantum information through quantum channels.Its main advantage is that it can realize absolutely secure communication between legitimate parties unconditionally.Quantum communication has good application prospects in the fields of military defense,financial secrecy and so on.The main quantum communication schemes include quantum key distribution,quantum secret sharing,quantum secure direct communication,quantum teleportation and so on.However,experimental device defects and channel noise limit the distance of quantum communication to a certain extent,and even introduce side channels to leave potential loopholes for eavesdroppers to intercept information.In this paper,we mainly study the theory of measurement-device-independent quantum communication,and focus on the study of measurement-device-independent quantum secure direct communication and quantum secret sharing.The relevant research findings can be summarized into the following three parts:First,we propose a long-distance measurement-device–independent quantum secure direct communication protocol.The protocol can eliminate security loopholes introduced by measurement device defects in quantum secure direct communication,and increase the quantum communication distance by introducing additional quantum network nodes.Second,we propose a deterministic measurement-device-independent quantum secret sharing protocol.The protocol can not only close security loopholes introduced by measurement device defects,but also eliminate the basis reconciliation process which is necessary in the measurement-device-independent quantum secret sharing.The quantum shared key can be deterministically generated among the parties involved in the communication,which greatly improves the shared key generation rate.In addition,the deterministic key sharing process can be directly transformed into a deterministic secret sharing process among multiple parties.Third,we propose a free-space single-photon quantum secure direct communication protocol based on decoherence-free space.The protocol takes advantage of the photon polarization and spatial-mode degrees of freedom that constitute a decoherence-free space to eliminate the influence of rotation noise,which is the main noise of polarization coding in free space communication.In principle,the detrimental effect introduced by either reference-frame misalignment or practical channel rotational noise is passively suppressed.