paper

Quantum Critical Detector : Amplifying Weak Signals Using First-Order Dynamical Quantum Phase Transitions

arXiv:1807.04617 · doi:10.1364/OE.27.010482

Abstract

We introduce a first-order quantum-phase-transition model, which exhibits giant sensitivity at the critical point. Exploiting this effect, we propose a quantum critical detector (QCD) to amplify weak input signals. The time-dynamic QCD functions by triggering a first-order dynamical quantum phase transition in a system of spins with long-range interactions coupled to a bosonic mode. We numerically demonstrate features of the dynamical quantum phase transition, which leads to a time-dependent quantum gain. We also show the linear scaling with the spin number in both the quantum gain and the corresponding signal-to-quantum noise ratio of this QCD. Our QCD can be a resource for metrology, weak signal amplification, and single photon detection.

10 pages, 8 figures

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