Nanomechanical single-photon routing

The active routing of photons using rapid reconfigurable integrated circuits is a key functionality for quantum-information processing. Typical waveguide-based optical switches rely on the modulation of the refractive index, producing a modest variation of the phase of the optical fields. Mechanical motion of nanophotonic structures, on the contrary, can be tailored to produce a much larger effect, without introducing loss or emitter decoherence and operating at a speed matching the quantum memory storage time of the on-chip quantum emitter. Here we demonstrate a compact and low-loss nano-opto-electromechanical single-photon router, based on two coupled waveguides whose distance is adjusted on demand by an external voltage. We show controllable two-port routing of single photons emitted from quantum dots embedded in the same chip. We report a maximum splitting ratio >23 dB, insertion loss of 0.67 dB, and sub-microsecond response time. The device is an essential building block for constructing advanced quantum photonic architectures on-chip, towards, e.g., coherent multi-photon sources, deterministic photon- photon quantum gates, quantum-repeater nodes, or scalable quantum networks. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement