Abstract
Photonic-integrated circuits have emerged as a scalable platform for complex quantum systems. A central goal is to integrate single-photon detectors to reduce optical losses, latency and wiring complexity associated with off-chip detectors. Superconducting nanowire single-photon detectors (SNSPDs) are particularly attractive because of high detection efficiency, sub-50-ps jitter and nanosecond-scale reset time. However, while single detectors have been incorporated into individual waveguides, the system detection efficiency of multiple SNSPDs in one photonic circuit—required for scalable quantum photonic circuits—has been limited to <0.2%. Here we introduce a micrometer-scale flip-chip process that enables scalable integration of SNSPDs on a range of photonic circuits. Ten low-jitter detectors are integrated on one circuit with 100% device yield. With an average system detection efficiency beyond 10%, and estimated on-chip detection efficiency of 14–52% for four detectors operated simultaneously, we demonstrate, to the best of our knowledge, the first on-chip photon correlation measurements of non-classical light.
Highlights
Photonic-integrated circuits have emerged as a scalable platform for complex quantum systems
To date there has been no scalable approach for integrating Superconducting nanowire single-photon detectors (SNSPDs) into Photonic-integrated circuits (PICs): while single, isolated waveguide-integrated SNSPDs have been demonstrated[17,18,19,20], the highest reported system detection efficiency (SDE) for just two SNSPDs integrated into the same photonic circuit remains significantly below 1%21,22
Hairpin-shaped SNSPDs17,18,24 were fabricated on B200-nm-thick silicon nitride (SiNx) membranes; silicon-on-oxide (SOI) PICs were fabricated separately
Summary
After evaluating the SNSPDs in a cryostat, highperformance detectors were selected from the fabrication chip and transferred onto high-performance SOI waveguides. Using this method, we assembled a proof-of-concept photonic circuit, shown, comprising an optical network with two input ports and four output ports, each coupled to an SNSPD. 25), resulting in a SDE (from the external fiber) up to 19±2% This system efficiency enables the first on-chip intensity autocorrelation measurements of non-classical light, demonstrated here for photon pairs generated by spontaneous parametric downconversion (SPDC). This SNSPD variant[26,27] has been shown to double the signal-to-noise ratio of the photodetection voltage compared with traditional single-wire SNSPDs. The detector length was designed using a
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