The effect of Homodyne-based feedback control on quantum speed limit time

The minimal time a system requires to transform from an initial state to target state is defined as the quantum speed limit time. quantum speed limit time can be applied to quantify the maximum speed of the evolution of a quantum system. Quantum speed limit time is inversely related to the speed of evolution of a quantum system. That is, shorter quantum speed limit time means higher speed of quantum evolution. In this work, we study the quantum speed limit time of a two-level atom under Homodyne-based feedback control. The results show that the quantum speed limit time is decreased by increasing feedback coefficient. So, Homodyne-based feedback control can induce speedup the evolution of quantum system

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

The minimum time a system needs to change from an initial state to a final orthogonal state is called quantum speed limit time. Quantum speed limit time can be used to quantify the speed of the quantum evolution. The speed of the quantum evolution will increase, if the quantum speed limit time decreases. In this work we will use relative purity based bound for quantum speed limit time. It is applicable for any arbitrary initial state. Here, we investigate the effects of filtering operation on quantum speed limit time. It will be observed that for some intervals of filtering operation parameter the quantum speed limit time is decreased by increasing filtering operation parameter and for some other intervals it is decreased by decreasing filtering operation parameter.Comment: 5 pages, 5 figure