Enhancing Quantum Parameter Estimation in Open Quantum System by Dynamical Decoupling Pulses

In this paper, we focus on studying how to enhance the precision of parameter estimation by dynamical decoupling (DD) pulses in an open system. Our results show that, when a qubit is subjected to a zero-temperature Ohmic-like dephasing reservoir, the quantum Fisher information (QFI) is determined by the decoherence function of this qubit. If the appropriate DD pulse frequency is selected, the decoherence in noisy environment can be effectively suppressed and the precision in parameter estimation can be enhanced. Moreover, we make a further comparison for the control effects between Uhrig dynamical decoupling (UDD) sequence and periodic dynamic decoupling (PDD) sequence in the sub-Ohmic and super-Ohmic environments. We find that, when the same DD pulses are applied to this qubit, UDD has obvious advantages over PDD in terms of improving precision of parameter estimation. This is because UDD can completely eliminate the adverse effect of environmental decoherence on parameter estimation.