Quantum Non-Hermitian Topological Sensors

TL;DR

This paper explores how non-Hermitian topological phases in quantum systems can be used to develop highly sensitive quantum sensors that detect boundary condition changes with exponentially increasing precision.

Contribution

It introduces a quantum-optical model of NH topological phases and demonstrates how boundary sensitivity can be harnessed for quantum sensing with exponential precision growth.

Findings

Exponential increase in detection precision with the number of modes

Identification of a resonance phenomenon enhancing sensitivity

Proposal of quantum NH topological sensors (QUANTOS)

Abstract

We investigate in the framework of quantum noise theory how the striking boundary-sensitivity recently discovered in the context of non-Hermitian (NH) topological phases may be harnessed to devise novel quantum sensors. Specifically, we study a quantum-optical setting of coupled modes arranged in an array with broken ring geometry that would realize a NH topological phase in the classical limit. Using methods from quantum-information theory of Gaussian states, we show that a small coupling induced between the ends of the broken ring may be detected with a precision that increases exponentially in the number of coupled modes, e.g. by heterodyne detection of two output modes. While this robust effect only relies on reaching a NH topological regime, we identify a resonance phenomenon without direct classical counterpart that provides an experimental knob for drastically enhancing the aforementioned exponential growth. Our findings pave the way towards designing quantum NH topological sensors (QUANTOS) that may observe with high precision any physical observable that couples to the boundary conditions of the device.