Exponentially-enhanced Quantum Non-Hermitian Sensing via Optimized Coherent Drive

TL;DR

This paper shows how optimizing the phase and position of coherent drive in multi-mode non-Hermitian systems can exponentially enhance quantum sensing capabilities, especially leveraging the skin effect for improved measurement precision.

Contribution

It introduces a method to optimize drive parameters in non-Hermitian quantum systems to achieve exponential enhancement in sensing performance, highlighting the role of the skin effect.

Findings

Optimized drive parameters can exponentially increase quantum Fisher information.

The skin effect can be harnessed for exponential sensing enhancement.

The protocol remains robust beyond linear response regimes.

Abstract

Distinct non-Hermitian dynamics has demonstrated its advantages in improving measurement precision over traditional sensing protocols. Multi-mode non-Hermitian lattice dynamics can provide exponentially-enhanced quantum sensing where the quantum Fisher information (QFI) per photon increases exponentially with the lattice size. However, somewhat surprisingly, it was also shown that the quintessential non-Hermitian skin effect does not provide any true advantage. In this paper, we demonstrate the importance of optimizing the phase of the coherent drive, and the position of the injection and detection in multi-mode non-Hermitian quantum sensing. The QFI per photon can be exponentially-enhanced or exponentially-reduced depending on parameters of the drive and detection. Specifically, it is demonstrated that for large amplification by choosing appropriate coherent drive parameters, the non-Hermitian skin effect can provide exponentially-enhanced quantum sensing. Moreover, in the regime beyond linear response, skin-effect can also provide a dramatic advantage as compared to the local perturbation, and the proposed protocol is robust in tuning the amplification factor.