| The positive operator-valued measurement(POVM)plays an important role in the field of quantum information.This paper focuses on the application of POVM in the measurement-device-independent quantum random number generator(MDI-QRNG)and the quantum random access code(QRAC),and the improvement of system performance is mainly discussed from the aspects of random code rate and channel loss resistance.1、Theoretical study of MDI-QRNG protocol under imperfect light sources.POVM plays an irreplaceable role in generating random numbers in MDI-QRNG.After performing corresponding POVM on the coded states at the transmitter under different light source intensities,we estimate and optimize the relevant parameter values,so as to improve the random key generation rate and enhance its channel loss-tolerant ability.However,due to the limitation of devices in practical application,the influence of light source flaws is inevitable.We mainly analyse the influence of light source flaws on random number generation under several different light sources,in addation,we also study the impact of finite-key effect on randomness,security and light source flaws.Finally,we propose the 4-intensity MDI-QRNG scheme,further improving the randomness and channel loss-tolerant ability.2、Theoretical research of QRAC based on POVM.In QRAC,POVM is particularly important in improving the successful probability of mutual guessing between two or even three communication parties,so as to ensure the security of communication tasks and avoid being attacked by eavesdroppers,it has stronger robustness.We transform the linear programming problem in the quantum field into a simple and understandable Gram matrix.Here,we apply the positive semi definite programming correlation method to realize the QRAC model,it includes that two receivers Alice,Bob under two inputs and three inputs respectively,we present three receivers QRAC model under two inputs by Gram matrix for the first time.Then we analyse the QRAC model of two receivers affected by noise under two inputs and three inputs respectively.Finally,we achieve the optimal strategy model of communication security through cooperation between two receivers under different noises.3、Research on the random number post-processing algorithm based on the parallel feedback shift register.For the generated initial random number sequence,we present several parallel feedback shift register random number post-processing algorithms and test them through the corresponding security authentication.We make a detailed performance comparison of several post-processing algorithms.After our post-processing operations,the Gaussian distribution with optical noise is uniformly distributed in different quantization intervals,the minimum entropy increases,which improve the security.We adopt the parallel shift register in the implementation mode,and the efficiency is greatly improved. |
