Active routing of single photons from quantum dots in GaAs photonic integrated circuits (Conference Presentation)

Abstract

Integrating semiconductor quantum dots (QDs) in planar photonic devices such as waveguides and photonic crystals, provides an excellent approach to develop on-chip quantum photonic circuits with deterministic photon-emitter interfaces [1]. To further scale up this technology, a key requirement is to develop reconfigurable circuitry that can be operated at a speed compatible with the emitter coherence time (0.1–1 μs) without adding excessive loss or emitter decoherence. The existing routing mechanisms, based on thermo-optic and electro-optic effects, do not meet these demands as they are either too slow or require very large footprints, limiting both scalability and efficiency. In this work, we demonstrate a different approach to on-chip routing by using nano-opto-electro-mechanical devices integrated with single-photon sources, i.e., InAs QDs in GaAs [2]. Unlike refractive-index-tuning methods, such opto-electro-mechanical interaction can be very strong at the nanoscale and, most importantly, material-independent [3], thus offering the advantage of a much smaller attainable device footprint, lower insertion loss, and faster switching speed. We report a gap-variable directional coupler whose splitting ratio is controlled mechanically via capacitive actuators, allowing us to perform disturbance-free routing of single photons emitted by embedded QDs with extinction ratios >20 dB and nW-level power consumption. Taking advantage of the reduced device footprint (<30 μm2) and the small dimension involved, we demonstrate sub-microsecond switching time (~370 ns) and a total insertion loss of 0.67 dB/switch. Such low loss and overall device performance are key to implementing networks of controllable quantum gates and schemes for on-chip photon de-multiplexing [4]. REFERENCES: [1] P. Lodahl, S. Mahmoodian, and S. Stobbe, “Interfacing single photons and single quantum dots with photonic nanostructures” Rev. Mod. Phys. 87, 347 (2015). [2] C. Papon et al. “Nanomechanical single-photon routing” arXiv preprint arXiv:1811.10962 (2018). [3] L. Midolo, A. Schliesser, and A. Fiore, “Nano-opto-electro-mechanical systems” Nat. Nanotechnol. 13(1), 11 (2018). [4] H. Wang et al. “Toward scalable boson sampling with photon loss” Phys. Rev. Lett., 120(23), 230502 (2018).