Measurement-device-independent Quantum Secure Direct Communication Of Multiple Degrees Of Freedom Of A Single Photon And Generation Of Hybrid Entanglement State

Since its inception,quantum information has always received extensive attention from researchers,especially in the fields of quantum measurement,quantum communication,and quantum cryptography.In 1984,Bennett and Brassard proposed the first quantum key distribution scheme.As an important branch of quantum communication,quantum key distribution has theoretically unconditional security,which has attracted the attention of scientists.With the deepening of research,scientists have discovered that the lack of ideal experimental equipment has led to loopholes in the quantum key distribution process,and there is a risk of eavesdropping.In order to avoid the security vulnerabilities caused by the defects of experimental equipment,scientists have successively proposed some effective communication schemes,such as device-independent quantum key distribution and measurement equipment-independent quantum key distribution.As another important branch of quantum communication,quantum secure direct communication also has the same problem.Due to the imperfection of the equipment,it leads to the leakage of information in the communication process.In order to solve the security vulnerabilities of quantum security direct communication,scientists have also conducted corresponding research.In 2018,Zhou and Sheng et al.proposed quantum secure direct communication that has nothing to do with measurement equipment.But in this scheme,photons are only encoded in one degree of freedom,so the amount of information that can be transmitted by each photon is low.In this paper,the first work is to propose a single-photon multi-degree-of-freedom measurement device-independent quantum secure direct communication scheme.By encoding separately on 3independent degrees of freedom,each photon can transmit 3 bits of information,which greatly improves the efficiency of quantum communication.Compared with the solution that does not use the measurement device-independent architecture,the communication distance is also extended,and at the end of the solution,the measurement device-independent quantum secure direct communication under any number of degrees of freedom coding is explained.As a vital resource in quantum communication,scientists have never stopped studying quantum entanglement.With the continuous improvement of entanglement research on the form of a single discrete or continuous variable,researchers have focused on the hybrid entanglement that can combine the advantages of the two variable forms.Since the first theoretical scheme for generating mixed entangled states was proposed in 1986,scientists have continued to study and put forward many experimentally achievable generation schemes,including the entanglement of the Fock state and the Schr?dinger cat state,and the polarization of the photon and the coherent state.Entanglement,photon time-bin is entangled with coherent state,etc.However,in the above scheme,the mixed entangled states are all Bell states.In this paper,the second work is to propose two different forms of mixed entangled state generation schemes,and consider the impact on the success probability and fidelity of the scheme when there is no perfect discrete input state in real conditions.By adding multiple forms of mixed entanglement to meet the communication needs in different scenarios.