Quantum speed limit time of a two-level atom under different quantum feedback control

Abstract

We investigate the quantum speed limit time (QSLT) of a two-level atom under quantum-jump-based feedback control or homodyne-based feedback control. Our results show that the two different feedback control schemes have different influences on the evolutionary speed. By adjusting the feedback parameters, the quantum-jump-based feedback control can induce speedup of the atomic evolution from an excited state, but the homodyne-based feedback control cannot change the evolutionary speed. Additionally, the QSLT for the whole dynamical process is explored. Under the quantum-jump-based feedback control, the QSLT displays oscillatory behaviors, which implies multiple speed-up and speed-down processes during the evolution. While, the homodyne-based feedback control can accelerate the speed-up process and improve the uniform speed in the uniform evolution process.

Controlling the quantum speed limit time for unital maps via filtering operations

“…It means that when QSL time is shortened, the speed of the quantum evolution will increase. Too much efforts have been done to obtain a short QSL time [17][18][19][20]. It has been shown that memory effects in non-Markovian dynamics of open quantum systems can reduce the QSL time [21].…”

Quantum discord of two-qutrit system under quantum-jump-based feedback control*

“…Markovian quantum feedback control introduced by Wiseman and Milburn [21,22] has been widely used to feed back measurements to the system to modify the future dynamics of the system, such as suppressing decoherence, [23][24][25][26] protecting quantum correlations, [27] improving steady state entanglement, [28][29][30][31][32][33] manipulating the geometric phase [34] and stationary state [35] of the dissipative two-level system, preparing a three-atom singlet, [36] W state, and GHZ state, [37,38] and enhancing the accuracy of parameter estimations. [39] Recently, quantum-jump-based feedback control has been used to accelerate quantum evolution, [40] enhance exciton transmission, [41] study on the dissipative stabilization of multipartite entanglement with Rydberg atoms, [42] maneuver Einstein-Podolsky-Rosen Steering, [43] and so on. According to different measurement strategies, homodyne-based and quantum-jump-based feedback controls are proposed.…”