Dynamical decoupling-assisted quantum parameter estimation with initial system-environment correlations

Decoherence is the main obstacle to quantum precision measurement. One must adopt appropriate control strategies to suppress decoherence. In this paper, we study the dephasing model of the system-environment with initial correlation, and use the quantum Fisher information (QFI) as the tool to explore the effect of dynamical decoupling pulses on inhibiting decoherence and improving the estimation precision of quantum parameters. We firstly study the influence of the initial correlations and initial quantum state on the dynamical evolution of a single qubit in this mode. Based on numerical calculations, in the Ohmic and the super-Ohmic thermal reservoir, we find that the periodic dynamical decoupling (PDD) sequence can significantly reduce the amplitude of the decoherence function, except for the anti-Zeno effect when the number of pulses is relatively small. By a judicious choice of the PDD pulse frequency, the dynamical decoupling pulses can effectively enhance the precision of quantum parameter estimation. And due to the peak structure existing in the decoherence function, the effect of applying Uhrig dynamical decoupling (UDD) sequence on the model is not ideal.

Automated summary

Decoherence is a significant obstacle in quantum precision measurement. This paper explores the impact of dynamical decoupling pulses on inhibiting decoherence and enhancing quantum parameter estimation precision through the dephasing model of system-environment with initial correlation. Results show that choosing the right PDD pulse frequency can effectively improve the precision of quantum parameter estimation, while the application of UDD sequence may not yield ideal results due to the peak structure in the decoherence function.