Fully integrated quantum photonic circuits show a clear advantage in terms of stability and scalability compared to tabletop implementations. They will constitute a fundamental breakthrough in integrated quantum technologies, as a matter of example, in quantum simulation and quantum computation. Despite the fact that only a few building blocks are strictly necessary, their simultaneous realization is highly challenging. This is especially true for the simultaneous implementation of all three key components on the same chip: single-photon sources, photonic logic, and single-photon detectors. Here, we present a fully integrated Hanbury-Brown and Twiss setup on a micrometer-sized footprint consisting of a GaAs waveguide embedding quantum dots as single-photon sources, a waveguide beamsplitter, and two superconducting nanowire single-photon detectors. This enables a second-order correlation measurement on the single-photon level under both continuous-wave and pulsed resonant excitation. The presented proof-of-principle experiment proves the simultaneous realization and operation of all three key building blocks and therefore a major step towards fully integrated quantum optical chips.
Publication:Fully On-Chip Single-Photon Hanbury-Brown and Twiss Experiment on a Monolithic Semiconductor–Superconductor Platform
Mario Schwartz, Ekkehart Schmidt, Ulrich Rengstl, Florian Hornung, Stefan Hepp, Simone L. Portalupi, Konstantin llin, Michael Jetter, Michael Siegel, and Peter Michler 
Nano Lett. 2018, 18, 11, 6892-6897
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Contact person: M. Schwartz