Quantum Non-Hermitian Topological Sensors

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.

5+4 pages, 4 figures, v2: updated to the published version

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• Restoration of the non-Hermitian bulk-boundary correspondence via topological amplification
• Stark localization as a resource for weak-field sensing with super-Heisenberg precision
• Non-Hermitian skin effect edge
• Quantum battery with non-Hermitian charging
• Bridging the gap between topological non-Hermitian physics and open quantum systems
• Driven-dissipative topological phases in parametric resonator arrays
• Nonreciprocal Amplification Transition in a Driven-Dissipative Quantum Network
• Real spectra and phase transition of skin effect in nonreciprocal systems