Optical transparency induced by a largely Purcell-enhanced quantum dot in a polarization-degenerate cavity

TL;DR

This paper demonstrates high-cooperativity coupling of a quantum dot to a specially designed cavity, achieving optical transparency and enabling efficient quantum control for quantum networks.

Contribution

It introduces a bullseye cavity with polarization-degenerate modes that enhances light-matter interaction and optical access for quantum dots.

Findings

Achieved cooperativity of 8 with a quantum dot in a bullseye cavity.

Observed 80 ps spontaneous emission lifetime with 15-fold Purcell enhancement.

Demonstrated approximately 80% optical transparency from the cavity.

Abstract

Optically-active spin systems coupled to photonic cavities with high cooperativity can generate strong light-matter interactions, a key ingredient in quantum networks. But obtaining high cooperativities for quantum information processing often involves the use of photonic crystal cavities that feature a poor optical access from the free space, especially to circularly polarized light required for the coherent control of the spin. Here, we demonstrate coupling with cooperativity as high as $8$ of an InAs/GaAs quantum dot to a fabricated bullseye cavity that provides nearly degenerate and Gaussian polarization modes for efficient optical accessing. We observe spontaneous emission lifetimes of the quantum dot as short as $80$ ps (a $\approx 15$ Purcell enhancement) and a $\approx 80\%$ transparency of light reflected from the cavity. Leveraging the induced transparency for photon switching while coherently controlling the quantum dot spin could contribute to ongoing efforts of establishing quantum networks.