Superconductor TDC for SNSPD Array Readout with 2.5 ps Time of Arrival Resolution

Superconducting Nanowire Single-Photon Detectors (SNSPDs) have become established as ultrafast, efficient detectors of single photons for quantum optics and astronomy. Recently, researchers at Argonne National Laboratory have demonstrated that similar detectors can also serve as ultrafast detectors of high-energy charged particles such as protons. Timing precision less than 3 ps has been measured. Large arrays of SNSPDs enable particle detection in future nuclear physics accelerator facilities. Precise differential timing will enable reconstruction of particle paths. However, readout of these arrays to room-temperature digital electronics will become more difficult for large arrays. A unique technology of ultrafast digital superconducting circuits is well matched to the superconducting sensor array. Specifically, a superconducting time-to-digital converter (TDC), with timing resolution to 6 ps was demonstrated earlier. Newer superconducting circuit technology will enable increased precision to 2.5 ps, which matches the precision of the detectors themselves. These can be scaled to multi-channel systems and integrated closely with the SNSPD array in the same cryogenic environment. Phase I: Design a superconducting TDC with 2.5 ps resolution which can be closely integrated with an SNSPD in an appropriate cryogenic system. Phase II: Fabricate a multi-channel TDC array, integrate it with a sensor array at a DoE Lab, and demonstrate its performance. 1) Design cryogenic assembly integrating superconducting TDC with SNSPD array. 2) Design experiments to be carried out at DoE Lab in Phase II. 3) Design custom superconducting TDC chip for testing in Phase II. An ultrafast TDC may have a variety of applications in precision timing in electronics and optics as well as particle physics, including for advanced medical instrumentation and quantum computing.