Exceptional-Point-Induced Sensitivity-Robustness Phase Transition in Quantum Interference

TL;DR

This paper uncovers a phase transition induced by exceptional points in a lossy quantum system, revealing regimes of ultrasensitive and robust quantum interference useful for sensing and information processing.

Contribution

It demonstrates a novel exceptional point induced phase transition in quantum interference within a lossy coupled waveguide system, bridging quantum sensing and robust quantum control.

Findings

Ultrasensitive interference in PT symmetric phase

Robust, oscillation-free interference in PT broken phase

Coincidence probability tunable via coupling strength

Abstract

Quantum interference underpins many quantum information protocols but is typically studied in lossless Hermitian systems. Here, we reveal an exceptional point induced phase transition in two photon Hong Ou Mandel interference within a lossy coupled waveguide system. In the PT symmetric phase. interference is ultrasensitive to coupling strength, yielding sharp bunching antibunching switches. In the PT broken phase. it becomes robust oscillation free and propagation independent with coincidence probability stably tunable via coupling. These regimes enable enhanced quantum sensing and reliable two photon control for robust quantum information processing.