| Quantum key distribution,as a branch of quantum mechanics in cryptography,can distribute keys securely between two legal parties,thereby achieving secure transmission of confidential information,whose theoretical security is guaranteed by Heisenberg's uncertainty principle and quantum non-clonable theorem.The key information carried by photons cannot be obtained by the attacker,meanwhile the attacker cannot copy the photons in the channel.Once an attacker attempts to measure the carrier photon to obtain information illegally,it will surely cause disturbance to the information system and be discovered by communication paries.The theoretical security of quantum key distribution can be completely guaranteed.The actual security of quantum key distribution protocols is deepening gradually.For the problem that the weak coherent state pulse Which is used to simulates an ideal single photon source is easily cracked by Photon Number Splitting,the decoy state protocol is commonly used to solve it.For the attack that steals key information by using actual instrument holes,many targeted methods have been proposed such as glare-blind attacks,etc.However,equipment loopholes cannot be completely covered,but such problems can be covered by quantum key distribution protocols that are independent of measurement equipment.In order to improve the practicality of quantum key distribution protocols,many new protocols have been proposed,which have improved the key generation rate continuously,and provided more basis for the practicality and commercialization of quantum key distribution in the future.The main research in this paper are as follows:(1)Three types of improved protocols for the BB84 protocol are studied,which are measurement-device-independent quantum key distribution protocol,twin-field quantum key distribution protocol,and phase matching quantum key distribution protocol.These three protocols are compared in the device implementation,decoy state method,photon source,interferometry type,key rate and security proof,which shows that phase encoding can improve the stability of optical pulse transmission effectively,moreover,single photon interference and phase post-compensation can further improve the key generation rate.(2)A new phase matching quantum key distribution protocol based on threestate system is proposed,and the security of the protocol is demonstrated in detail.The protocol is simulated based on classic data and the simulation result shows that this protocol breaks the limitation of the linear key generation rate in a shorter distance,increases the key rate and makes the effective transmission distance longer. |
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