|
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).
|
