Research On Enhancing The Capacity Of Quantum Super Dense Coding Via Environment-assisted Measurement

Quantum super dense coding is not only one of the important research fields of quantum information processing,but also one of the most interesting applications of quantum entanglement sharing.It provides preconditions for the absolute security of global quantum secure communication.As an indispensable resource for quantum super dense coding,entanglement can double the classical information capacity in noise-free quantum channels.However,the actual quantum system inevitably interacts with the surrounding environment,thus the entanglement is attenuated,which greatly reduces the efficiency of super dense coding,and even the case where the quantum super dense coding is inferior to the classical coding.Therefore,it is necessary to find schemes which can suppress the environmental decoherence,protect entanglement and enhance the capacity of super dense coding.The technique of environment-assisted measurement can obtain additional information from the environment to suppress decoherence effectively,and plays an important role in the processing of quantum information tasks.In this paper,we study the use of environment-assisted measurement technique to suppress decoherence and enhance the capacity of quantum super dense coding under the influence of noise.The main research contents and innovations are as follows:(1)A scheme for improving the capacity of super dense coding under amplitude damping noise using environment-assisted measurement is proposed.With the help of environmentassisted measurement and quantum measurement reversal,the influence of the amplitude damping noise can be effectively suppressed,and the capacity before the noise is recovered with a certain probability.Compared with the results obtained by the scheme of weak measurement and quantum measurement reversal,the scheme of environment-assisted measurement and quantum measurement reversal have obvious advantages in improving the capacity and the probability of success.These advantages stem from the fact that the technique of environment-assisted measurement can extract additional information from the environment to suppress amplitude damped noise.(2)When channels are continuously used,the quantum channels with correlated effects are the realistic scenarios for studying noisy quantum communication.On the basis of discussing the capacity of super dense coding under correlated amplitude damping channel,two schemes of weak measurement and quantum measurement reversal are used to enhance the capability of super dense coding.The results show that the two schemes can effectively suppress correlated amplitude damping noise and increase the capacity with a certain probability.However,the first scheme can improve the capacity better,but the probability of success is lower;the second scheme has a lack of capacity,but the probability of success is higher.(3)A scheme to enhance the capacity of super dense coding under correlated amplitude damping noise by using environment-assisted measurement.The results show that the technique of environment-assisted measurement can effectively suppress the influence of the correlated amplitude damping noise and recover the capacity before the noise with a certain probability.Compared with the previous two schemes of weak measurement and quantum measurement reversal,the scheme of environment-assisted measurement and quantum measurement reversal has advantages in increasing capacity and probability of success.This provides a possible way to suppress the noise and effectively perform quantum information processing.