Anomalous spontaneous emission dynamics at chiral exceptional points

TL;DR

This paper analytically explores how chiral exceptional points in microcavities influence spontaneous emission, revealing phenomena like EP-induced transparency, linewidth narrowing, and atom-photon bound states, with implications for quantum optics applications.

Contribution

It provides the first analytical description of LDOS at chiral EPs and uncovers novel emission dynamics, including destructive interference effects and population trapping, advancing quantum cavity QED understanding.

Findings

Null Purcell enhancement at specific frequencies due to destructive interference.

Linewidth narrowing of Rabi splitting below bare component levels.

Support for atom-photon bound states enabling population trapping.

Abstract

An open quantum system operated at the spectral singularities where dimensionality reduces, known as exceptional points (EPs), demonstrates distinguishing behavior from the Hermitian counterpart. Here, we present an analytical description of local density of states (LDOS) for microcavity featuring chiral EPs, and unveil the anomalous spontaneous emission dynamics from a quantum emitter (QE) due to the non-Lorentzian response of EPs. Specifically, we reveal that a square Lorentzian term of LDOS contributed by chiral EPs can destructively interfere with the linear Lorentzian profile, resulting in the null Purcell enhancement to a QE with special transition frequency, which we call {\it{EP induced transparency}}. While for the case of constructive interference, the square Lorentzian term can narrow the linewidth of Rabi splitting even below that of bare components, and thus significantly suppresses the decay of Rabi oscillation. Interestingly, we further find that an open microcavity with chiral EPs supports atom-photon bound states for population trapping and decay suppression in long-time dynamics. As applications, we demonstrate the advantages of microcavity operated at chiral EPs in achieving high-fidelity entanglement generation and high-efficiency single-photon generation. Our work unveils the exotic cavity quantum electrodynamics unique to chiral EPs, which opens the door for controlling light-matter interaction at the quantum level through non-Hermiticity, and holds great potential in building high-performance quantum-optics devices.