Variational quantum metrology for multiparameter estimation under dephasing noise

TL;DR

This paper introduces a hybrid variational quantum-classical method to improve multiparameter estimation precision in quantum metrology, especially under dephasing noise, surpassing classical limits.

Contribution

It proposes a novel variational scheme optimizing both initial states and measurement bases for enhanced quantum metrology under noise.

Findings

Successfully estimates multiple parameters simultaneously

Surpasses the standard quantum limit in noisy environments

Applicable to 3D magnetic field sensing

Abstract

We present a hybrid quantum-classical variational scheme to enhance precision in quantum metrology. In the scheme, both the initial state and the measurement basis in the quantum part are parameterized and optimized via the classical part. It enables the maximization of information gained about the measured quantity. We discuss specific applications to 3D magnetic field sensing under several dephasing noise modes. Indeed, we demonstrate its ability to simultaneously estimate all parameters and surpass the standard quantum limit, making it a powerful tool for metrological applications.