Quantum non-Hermitian topological sensors

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