Filter-free single-photon quantum dot resonance fluorescence in an integrated cavity-waveguide device

TL;DR

This paper presents a novel integrated cavity-waveguide device that enables filter-free, resonant excitation of quantum dots for efficient single-photon generation, simplifying operation and potentially increasing photon rates for quantum photonics.

Contribution

It introduces a new integrated device design that allows resonant excitation without filtering, enhancing efficiency and simplifying quantum dot single-photon sources.

Findings

Achieved filter-free resonant excitation of quantum dots.

Demonstrated efficient off-chip single-photon collection.

Potential for scalable chip-scale quantum photonics.

Abstract

Semiconductor quantum dots embedded in micro-pillar cavities are excellent emitters of single photons when pumped resonantly. Often, the same spatial mode is used to both resonantly excite a quantum dot and to collect the emitted single photons, requiring cross-polarization to reduce the uncoupled scattered laser light. This inherently reduces the source brightness to 50 %. Critically, for some quantum applications the total efficiency from generation to detection must be over 50 %. Here, we demonstrate a resonant-excitation approach to creating single photons that is free of any cross-polarization, and in fact any filtering whatsoever. It potentially increases single-photon rates and collection efficiencies, and simplifies operation. This integrated device allows us to resonantly excite single quantum-dot states in several cavities in the plane of the device using connected waveguides, while the cavity-enhanced single-photon fluorescence is directed vertical (off-chip) in a Gaussian mode. We expect this design to be a prototype for larger chip-scale quantum photonics.