Quantum parameter estimation with optimal control

TL;DR

This paper demonstrates how optimal control techniques can enhance quantum parameter estimation, surpassing traditional precision limits constrained by coherent time, by exploiting additional controllable degrees of freedom.

Contribution

It introduces a novel approach applying optimal control to quantum metrology, enabling precision improvements beyond standard bounds dictated by coherent time.

Findings

Controlled schemes achieve higher precision limits.

Precision can surpass bounds set by coherent time.

Optimal control extends quantum metrology capabilities.

Abstract

A pivotal task in quantum metrology, and quantum parameter estimation in general, is to de- sign schemes that achieve the highest precision with given resources. Standard models of quantum metrology usually assume the dynamics is fixed, the highest precision is achieved by preparing the optimal probe states and performing optimal measurements. However, in many practical experimental settings, additional controls are usually available to alter the dynamics. Here we propose to use optimal control methods for further improvement on the precision limit of quantum parameter estimation. We show that by exploring the additional degree of freedom offered by the controls higher precision limit can be achieved. In particular we show that the precision limit under the controlled schemes can go beyond the constraints put by the coherent time, which is in contrast to the standard scheme where the precision limit is always bounded by the coherent time.