paper

Quantum squeezing and sensing with pseudo anti-parity-time symmetry

arXiv:2108.12873 · doi:10.1103/PhysRevLett.128.173602

Abstract

The emergence of parity-time () symmetry has greatly enriched our study of symmetry-enabled non-Hermitian physics, but the realization of quantum -symmetry faces an intrinsic issue of unavoidable symmetry-breaking Langevin noises. Here we construct a quantum pseudo-anti- (pseudo-) symmetry in a two-mode bosonic system without involving Langevin noises. We show that the spontaneous pseudo- symmetry breaking leads to an exceptional point, across which there is a transition between different types of quantum squeezing dynamics, i.e., the squeezing factor increases exponentially (oscillates periodically) with time in the pseudo- symmetric (broken) region. Such dramatic changes of squeezing factors and quantum dynamics near the exceptional point are utilized for ultra-precision quantum sensing. These exotic quantum phenomena and sensing applications can be experimentally observed in two physical systems: spontaneous wave mixing nonlinear optics and atomic Bose-Einstein condensates. Our work offers a physical platform for investigating exciting symmetry physics in the quantum realm, paving the way for exploring fundamental quantum non-Hermitian effects and their quantum technological applications.

6 + 8 pages, 3 + 3 figures. To appear in PRL

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