The driving and counting electronics for the Superconducting Nanowire Single Photon Detectors (SNSPDs) fabricated and commercialized by Single Quantum (SQ) is currently designed to interface with at most 8 SNSPD channels. Single Quantum is already selling 24 channel systems and the trend is generally towards more channels. In those systems, multiple 8 channel drivers have been used in parallel. However, a redesign of the electronics is needed to allow such system to interface with an arbitrary number of channels, hence enabling new application areas, such as biomedical imaging.
Currently, each channel uses up to 5W of power, which hinders a larger densely packed system. In addition, the current implementation has a counting dead-time of about 20 ms, which gives a significant slowdown in characterizing the SNSPD. And last, the SNSPD might occasionally latch into resistive state and needs to be actively quenched back into superconducting state but the current system is not always able to perform such operation.
This project addresses those issues by making the system scalable in n x 12 channels, reducing the high power consumption on each channel to 2.9 W, proposing a new counting mechanism such that the characterization of an SNSPD is sped up and all photon detections are counted, and proposing a new way to actively quench all types of SNSPD implementations.
The functionality for a 12 channel system is split in Channel Units and a Main Control Unit. The channel units count, bias and control a single SNSPD and communicate with the main control unit through a CAN-FD bus. The main control unit communicates all data from the channel units to the Graphical User Interface (GUI) through ethernet and vice versa translate
the control commands from the Graphical User Interface to the channel units. All units are based on the LPC54618 microcontroller by NXP.
The newly designed system has been tested to work for up to 12 channels, and can be housed in a 19 inch rack mountable enclosure. Using an ethernet switch allows for interfacing with n x 12 channel systems.
This system design paves the way towards the bias and readout of, for instance, a 10x10 SNSPD array such that detailed spatial information may be added at the single photon level.