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SYPD: PhD Symposium - Solid-state Quantum Emitters Coupled to Optical Microcavities
SYPD 1: Solid-state quantum emitters coupled to optical microcavities
SYPD 1.2: Invited Talk
Monday, March 14, 2022, 17:00–17:30, AKjDPG-H17
A fast and bright source of coherent single-photons using a quantum dot in an open microcavity — •Richard J. Warburton — Department of Physics, University of Basel, Switzerland
A semiconductor quantum dot is a potentially excellent source of single photons: billions of photons per second can be created; the interaction with phonons is relatively weak such that successively emitted photons exhibit a high degree of two-photon interference. Significant challenges are to create an efficient source, and to reduce the noise such that photons created far apart in time also exhibit a high degree of two-photon interference. We show how these challenges can be met by embedding a gated quantum-dot in an open microcavity.
In our gated devices, quantum dots exhibit near transform-limited linewidths, both at wavelengths in the near infrared (920–950 nm) and in the near-red (around 780 nm). A microcavity is constructed using a planar semiconductor bottom mirror (part of the semiconductor heterostructure) and a curved top mirror. With a very high-reflectivity top mirror, a single quantum-dot enters the strong-coupling regime of cavity-QED with a cooperativity exceeding 100. Clear vacuum Rabi-oscillations are observed. With a modest-reflectivity top mirror, an efficient single-photon source is demonstrated. The end-to-end efficiency, the probability of creating a single photon at the output of the experiment’s final optical-fibre following a trigger, is 57%; the photon purity (1−g(2)(0)) is 97.9%; the two-photon interference visibility is 97.5% and is maintained even on interfering photons far apart in time (1.5 µs in the experiment).