Enhanced Quantum Parameter Estimation via Dynamical Modulation

TL;DR

This paper introduces a dynamical modulation scheme that enhances quantum parameter estimation precision by manipulating system dynamics and increasing quantum Fisher information, applicable in quantum metrology tasks.

Contribution

The proposed method improves quantum estimation accuracy by dynamically controlling system parameters, surpassing traditional decoupling techniques, and is demonstrated with Ramsey spectroscopy and quantum thermometer examples.

Findings

Quantum Fisher information is significantly increased.

Estimation precision is enhanced regardless of parameter origin.

Applicable to various quantum metrology applications.

Abstract

In quantum theory, the inescapable interaction between a system and its surroundings would lead to a loss of coherence and leakage of information into the environment. An effective approach to retain the quantum characteristics of the system is to decouple it from the environment. However, things get complicated in quantum parameter estimation tasks, especially when the unknown parameter originates from the environment. Here, we propose a general dynamical modulation scheme that enables the enhancement of estimation precision irrespective of the origin of the parameters to be estimated. Notably, beyond the capability of dynamically decoupling the system from the environment, our proposal can select the effective frequency of the system and in turn manipulate the dynamics of the system, such as the steady-state probability and the decay rate, which are sensitive to the bath parameter. Therefore, the quantum Fisher information is dramatically increased, leading to superior estimation precision. Specifically, we elucidate the effectiveness of our proposal with prototypical examples of the Ramsey spectroscopy and quantum thermometer. Our findings offer an alternative route to enhance the precision of quantum estimation processes and may have potential applications in diverse branches of quantum metrology.