Long-lived quantum correlation by cavity-mediated subradiance

TL;DR

This paper demonstrates a long-lived subradiant quantum state among multiple emitters in a cavity, showing potential for quantum information storage and manipulation through controlled photon statistics and entanglement.

Contribution

It introduces a method to generate and control cavity-mediated subradiance in quantum emitters, enabling long-lived quantum correlations for quantum technologies.

Findings

Observation of a steady-state subradiant population with highly negative cooperativity

Large photon bunching indicating strong quantum correlations

Control of emitter number and dephasing via excitation wavelength

Abstract

Cooperative effects such as super(sub)radiance in quantum systems arise from the interplay among quantum emitters. While bright superradiant states have been extensively studied and yielded significant insights into cooperative phenomena, subradiant states have remained less explored due to their inherently dark state nature. However, subradiance holds significant potential as valuable quantum resources that exploit long-lived and large-scale entanglement, which is a key for advancing quantum information technologies. Here, we demonstrate a long-lived subradiant state among multiple quantum emitters coupled to a directional low Q cavity. In a tailored photonic environment with balanced cavity dissipation, emitter-field coupling strength, and incoherent pumping, two coupled quantum dots exhibit a steady-state population in a subradiant state with highly negative cooperativity. As an important hallmark of a subradiant state, the system shows large photon bunching (g^((2))(0)>>2) and suppressed single-photon decay. In addition, controlling the excitation wavelength provides a useful tool for manipulating dephasing and the number of coupled emitters, which leads to significant changes in photon statistics. Our approach to inducing cavity-mediated subradiance paves the way for creating and harnessing quantum correlations in quantum emitters via a long-lived entangled quantum state, essential for quantum storage and metrology.