On-chip Non-Hermitian Cavity Quantum Electrodynamics

TL;DR

This paper demonstrates the experimental control of quantum vacuum fluctuations using non-Hermitian exceptional points in an integrated lithium niobate-GaAs microcavity platform, enabling novel quantum light-matter interaction effects.

Contribution

It introduces a hybrid LN-GaAs platform with dynamic tuning of chiral exceptional points, leading to unprecedented control over spontaneous emission and spectral shaping in quantum photonics.

Findings

7-fold modulation of spontaneous emission lifetime

Generation of non-Lorentzian spectral profiles

Reversible engineering of quantum vacuum fluctuations

Abstract

Exceptional points (EPs) promise revolutionary control over quantum light-matter interactions. Here, we experimentally demonstrate flexible and reversible engineering of quantum vacuum fluctuation in an integrated microcavity supporting chiral Eps. We develop a hybrid lithium niobate (LN)-GaAs quantum photonic platform, seamlessly combining high-quality quantum emitters, a low-loss photonic circuit, efficient electro-optic (EO) effect, and local strain actuator in a single device. Chiral EPs are implemented by dynamically tuning the coupling between the modes associated with a micro-ring resonator, resulting in anomalous spontaneous emission dynamic with a 7-fold modulation of the lifetime (120 ps to 850 ps). Meanwhile, we reshape single-photon spectra via cavity local density of states (LDOS) engineering and generate non-Lorentzian spectral profiles: squared-Lorentzian, Fano-like, and EP-induced transparency (EPIT), a suppression of emission at zero detuning. This work unveils exotic cavity quantum electrodynamics (cQED) effects unique to EPs and establishes a universal paradigm for non-Hermitian quantum photonics.