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Integrated quantum photonics offers a promising path to scale up quantum optics experiments by miniaturizing and stabilizing complex laboratory setups. Central elements of quantum integrated photonics are quantum emitters, memories, detectors, and reconfigurable photonic circuits. In particular, integrated detectors not only offer optical readout but, when interfaced with reconfigurable circuits, allow feedback and adaptive control, crucial for deterministic quantum teleportation, training of neural networks, and stabilization of complex circuits. However, the heat generated by thermally reconfigurable photonics is incompatible with heat-sensitive superconducting single-photon detectors, and thus their on-chip co-integration remains elusive. Here we show low-power microelectromechanical reconfiguration of integrated photonic circuits interfaced with superconducting single-photon detectors on the same chip. We demonstrate three key functionalities for photonic quantum technologies: 28 dB high-extinction routing of classical and quantum light, 90 dB high-dynamic range single-photon detection, and stabilization of optical excitation over 12 dB power variation. Our platform enables heat-load free reconfigurable linear optics and adaptive control, critical for quantum state preparation and quantum logic in large-scale quantum photonics applications.

Photonic integrated circuits have seen a dramatic increase in complexity over the past decades. This development has been spurred by recent applications in datacenter communications and enabled by the availability of standardized mature technology platforms. Mechanical movement of wave-guiding structures at the micro-and nanoscale provides unique opportunities to further enhance functionality and to reduce power consumption in photonic integrated circuits. We here demonstrate integration of MEMS-enabled components in a simplified silicon photonics process based on IMEC's Standard iSiPP50G Silicon Photonics Platform and a custom release process.

Programmable photonic integrated circuits are emerging as an attractive platform for applications such as quantum information processing and artificial neural networks. However, current programmable circuits are limited in scalability by the lack of low-power and low-loss phase shifters in commercial foundries. Here, we demonstrate a compact phase shifter with low-power photonic MEMS (micro-electro-mechanical systems) actuation on a silicon photonics foundry platform (IMEC's iSiPP50G). The device attains (2.9π ± π) phase shift at 1550 nm, with an insertion loss of (0.33 + 0.15 − 0.10 ) dB, a V π of (10.7 + 2.2 − 1.4 ) V, and an L π of (17.2 + 8.8 − 4.3 ) µm. We also measured an actuation bandwidth f -3dB of 1.03 MHz in air. We believe that our demonstration of a low-loss and low-power photonic MEMS phase shifter implemented in silicon photonics foundry compatible technology lifts a main roadblock towards the scale-up of programmable photonic integrated circuits.

Efficient on-chip integration of single-photon emitters imposes a major bottleneck for applications of photonic integrated circuits in quantum technologies. Resonantly excited solid-state emitters are emerging as near-optimal quantum light sources, if not for the lack of scalability of current devices. Current integration approaches rely on cost-inefficient individual emitter placement in photonic integrated circuits, rendering applications impossible. A promising scalable platform is based on two-dimensional (2D) semiconductors. However, resonant excitation and single-photon emission of waveguide-coupled 2D emitters have proven to be elusive. Here, we show a scalable approach using a silicon nitride photonic waveguide to simultaneously strain-localize single-photon emitters from a tungsten diselenide (WSe 2 ) monolayer and to couple them into a waveguide mode. We demonstrate the guiding of single photons in the photonic circuit by measuring second-order autocorrelation of g (2) (0) = 0.150 ± 0.093 and perform on-chip resonant excitation, yielding a g (2) (0) = 0.377 ± 0.081. Our results are an important step to enable coherent control of quantum states and multiplexing of highquality single photons in a scalable photonic quantum circuit.