Application Of Quantum Control In Parameter Estimation Theory

Quantum parameter estimation theory concerns how to make high-precision measurement of unknown physical parameters by quantum resources.It is a basic topic in many research fields,such as atomic clocks,gravitational wave detectors and so on.Ultra high-precision parameter estimation is of particular significance for frontier science and practical engineering.The achievable accuracy of quantum parameter estimation will be limited by the influence of environmental decoherence.This paper mainly studies the effectiveness of quantum control method in effectively suppressing decoherence and improving the accuracy of parameter estimation.The main results are as follows:1.We analyze the accuracy of parameter estimation under quantum control scheme.Weak measurement can improve the parameter estimation accuracy under the influence of decoherence,but the success probability is relatively low.We improve the simple weak measurement scheme and introduce quantum control to further improve the success probability.Then we analyze the accuracy of this scheme and explain the theoretical results,which provides a reference for improving the accuracy limit and success probability.2.We propose a compromise between parameter estimation accuracy and success probability.We improve the scheme of combining weak measurement with quantum control,and theoretically analyze the accuracy limit and success probability of the new scheme.Then we use numerical simulation to compare the accuracy limits of each scheme.The new scheme can improve the accuracy of parameter estimation compared with the parameter estimation under the influence of decoherence.Although the accuracy can not reach the Heisenberg limit under the simple weak measurement scheme,new scheme improves the success prob ability of parameter estimation.