Enhancing real-time parameters estimation precision by quantum jump-based feedback control

Abstract

Real-time quantum parameter estimation is the basis of quantum feedback control and adaptive control. In this paper, the possibility of real-time estimating the feedback coefficient and dissipation rate is discussed by means of quantum Fisher information. We find that: (1) whether the feedback coefficient λ or dissipation rate γ⁡, an effective way to estimate is adjusting the initial state of system to 0 (θ=0); (2) for a given initial state 0, the estimation precision of feedback coefficient depends on the feedback coefficient itself. If it is bounded in ⁡⁡λ≤π/2, then the closer the feedback coefficient is near ⁡⁡λ=π/2, the more accurate the estimation of the feedback coefficient is; (3) when estimating the dissipation parameter, we should avoid setting the feedback parameter to λ=⁡⁡π/2 in order to improve the precision of estimation. At this time, there are some optimized values of feedback parameter, and under these values, the information the system dissipates is exactly equal to that the feedback compensates, the system reaches a dynamic balance. Quantum Fisher information can also be maintained at a high value for a long time so as to estimate the dissipation parameter with a high accuracy.