Quantum nature of a strongly coupled single quantum dot–cavity system

Abstract

Cavity quantum electrodynamics (QED) studies the interaction between a quantum emitter and a single radiation-field mode. When an atom is strongly coupled to a cavity mode, it is possible to realize important quantum information processing tasks, such as controlled coherent coupling and entanglement of distinguishable quantum systems. Realizing these tasks in the solid state is clearly desirable, and coupling semiconductor self-assembled quantum dots to monolithic optical cavities is a promising route to this end. However, validating the efficacy of quantum dots in quantum information applications requires confirmation of the quantum nature of the quantum-dot-cavity system in the strong-coupling regime. Here we find such confirmation by observing quantum correlations in photoluminescence from a photonic crystal nanocavity interacting with one, and only one, quantum dot located precisely at the cavity electric field maximum. When off-resonance, photon emission from the cavity mode and quantum-dot excitons is anticorrelated at the level of single quanta, proving that the mode is driven solely by the quantum dot despite an energy mismatch between cavity and excitons. When tuned to resonance, the exciton and cavity enter the strong-coupling regime of cavity QED and the quantum-dot exciton lifetime reduces by a factor of 145. The generated photon stream becomes antibunched, proving that the strongly coupled exciton/photon system is in the quantum regime. Our observations unequivocally show that quantum information tasks are achievable in solid-state cavity QED.

Exciton-plasmon coupling interactions: from principle to applications

“…A new polaron is formed by the interaction between light and excitons, and the formation may also lead to the Bose-Einstein condensation [75]. In the field of quantum information, strong coupling can achieve quantum coherent oscillation, which plays a key role in quantum information processing [76]. Moreover, the EM environment of fluorophore can be changed by strong coupling [77], so it can be used to change the threshold of the chemical reaction and control the rate of chemical reactions.…”

A lithographic approach for quantum dot-photonic crystal nanocavity coupling in dilute nitrides

“…One of the main strategies for integrating a QD into an optical cavity is the fabrication of a photonic crystal (PhC) cavity around a selected QD [3]. The main drawback of this approach is the difficulty of obtaining the isolation of a single high-quality QD and of deterministically matching it both spatially and spectrally with the PhC cavity modes.…”

The role of phonons for exciton and biexciton generation in an optically driven quantum dot

“…Currently also the optical control of QDs in a microcavity has come into the focus of attention, where vacuum Rabi oscillations and the corresponding vacuum Rabi splitting are seen as indications for reaching the strong coupling regime between light and matter [176,177,178,179]. In the case of strong light-matter coupling there is a strong interplay between exciton-phonon and light-matter interaction, which for example can be seen in the line-width broadening in the Mollow-Triplet [180,102].…”