Non-Hermitian Michelson interferometer for exceptional-point-enhanced sensing
Phys. Rev. A 114, 043718 – Published 14 October, 2026
DOI: https://doi.org/10.1103/ssrq-2fb2
Abstract
The Michelson interferometer underpins modern optical metrology, enabling precise measurements of displacement and gravitational waves. However, the sensitivity of the conventional Hermitian Michelson interferometer is inherently limited by its linear response to a perturbation. Here, we propose a non-Hermitian Michelson interferometer by introducing a coupling between two arms with reservoir engineering, forming a configuration of light cross. The eigenfrequency splitting as a spectral response displays a square-root dependence on a perturbation. Remarkably, the quantum Fisher information of our non-Hermitian Michelson interferometer can exceed that of its Hermitian counterpart by more than three orders when Brownian noise is included, implying a great enhancement in sensitivity. This work provides a framework for non-Hermitian interferometric sensing with unprecedented sensitivity.
