We present the integration of quantum emitters, nanophotonic circuit components and waveguide-integrated superconducting nanowire single-photon detectors with photonic integrated circuits on silicon chips as a versatile platform for applications in quantum technology.
Abstract Integrated photonics is expected to play a key role in the scalability of quantum systems for applications such as quantum computing, quantum communications, quantum internet, and quantum metrology. One of the primary components of quantum integrated photonics is a single photon detector, which reads out the quantum information encoded in photons. Amongst available single-photon detection schemes, superconducting nanowire single photon detectors (SNSPDs) remain the most promising technology for effective on-chip coupling, because they can be seamlessly integrated with a wide range of waveguide materials and substrates and have shown unparalleled performance from visible to the mid-infrared regime. Here, we review different aspects of SNSPDs and schemes for their on-chip integration for different integrated photonics applications. Although mostly concentrated on quantum applications, we also cover some of the important wider photonics applications including imaging, AI and machine learning, and single-photon spectroscopy, and conclude the review with a future outlook discussing emerging research areas enabled by photonic integrated circuits based on SNSPDs.
Photonic integrated quantum circuits could fully unlock quantum systems' potential. However,monololithic platforms face several challenges. We explore hybrid quantum photonic integration, combining different photonic materials to mitigate monolithic approaches disadvantages . Our work introduces hybrid circuits integrating different quantum sources and materials. We present a technique integrating nanowire single photon sources with silicon nitride waveguides, enabling circuit reconfiguration and emission wavelength control using heat, and strain tuning which is compatible with superconducting single photon detectors . We realize a full quantum transceiver on chip using on demand single photon sources and SNSPDS, in additio to dispersion engineering of superconducting transmission lines for SNSPDs multi-pixel integration. We discuss progress towards room-temperature quantum integrated photonics using hexagonal boron nitride quantum emitters. Finally, we delve into scalable generation and quantum state reconstruction of W-states and construction using phase retrieval algorithms, and ongoing research on topological photonics, and photonic lattices.
In recent years, research on integrated quantum circuits has developed rapidly and exciting results have been achieved. The overarching goal of this emerging research direction in the field of modern quantum technology is the scalable integration of quantum functionality on robust chips. Such chips can work independently of one another, but it is even more interesting to develop them modularly for integration into larger quantum networks, thereby linking quantum computation and quantum communication in the same framework. In this context, the ongoing development and further optimization of integrated quantum circuits aim, inter alia, to achieve a quantum advantage in the area of quantum computing and to pave the way for multipartite quantum networks. The functionality of such chips is essentially based on single-photon operations, such as interference at beam splitters in combination with phase shifters in the field of linear optical quantum computing and Bell-state measurements for entanglement swapping in long-distance quantum networks. While individual functionalities such as CNOT gates and more complex quantum computing operations such as boson sampling in a combination of waveguide chips and external photon sources and detectors were successfully demonstrated, the field is currently facing the major challenge of integrating all necessary components monolithically on chip in order to exploit the full potential of integrated quantum nanophotonics. The present Perspective discusses the status and the present challenges of integrated quantum nanophotonics based on on-demand single-photon emitters and gives an outlook on required developments to enter the next level of fully functional quantum circuits for photonic quantum technology.