  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.
