Design principles for efficiency and indistinguishability broadband quantum dot cavities

Abstract

Quantum dots have the potential to be one of the brightest deterministic single photon sources with high end applications in quantum computing and cluster state generation. In this work, we re-examine the design of plain micropillars by meticulously examining the structural effects of the decay into leaky channels beyond an atom-like cavity estimation. We show that precise control of the side losses with the diameter and avoidance of propagating Bloch modes in the distributed Bragg reflectors can result in easy-to-manufacture broadband ( $\mathit{Q}\approx750$ –2500) micropillars, allowing for broad optical coherent control pulses necessary for high single photon purity ( $ {\gt}$ 99.2%–99.99% achievable) while simultaneously demonstrating extremely high efficiency out the top (90.5%–96.4%). We also demonstrate that such cavities naturally decouple from the phonon sideband, with the phonon sideband reducing by a factor of 5–33 allowing us to predict that the photons should show 98.5%–99.8% indistinguishability without the need for filtering.

Keywords

• quantum dot
• micropillar
• cavity quantum electrodynamics
• single photon sources
• Purcell effect
• solid state emitters