Multiplexing techniques for detector applications - basics and its realization in superconducting electronics

Sonja Engert, Olaf Wetzstein, M. Hofherr +4 more

Superconducting nanowire single photon detectors (SNSPDs) are distinguished by a very high sensitivity, a broad spectral range and a sparse dark count rate. Therefore, arrays of SNSPDs enable novel ultrasensitive imaging applications. The goal is to realize large arrays in the near future. Hence, in order to improve detector systems, there is the necessity to develop multiplexing techniques to keep the number of wires in the cryogenic environment as low as possible. We realized a readout circuit with rapid single flux quantum electronics. All detector output signals were merged to a single output channel. This leads to a loss of spatial resolution of the information provided by the single pixels. In order to overcome this effect, this work describes a theoretical analysis of time and code multiplexing technique for arrays of SNSPDs and a comparison concerning their applicability in different cases. We developed rules for the usability of each multiplexing technique and verified the results with measurements of a 4-pixel SNSPD array.

K. D. Irwin, Hsiao-Mei Cho, William Bertrand Doriese +7 more

Johann Heyen Hinken

Jonas Stasys Zmuidzinas, P. L. Richards

Superconducting detectors will play an increasingly significant role in astrophysics, especially at millimeter through far-IR wavelengths, where the scientific opportunities include key problems in astronomy and cosmology. Superconducting detectors offer many benefits: outstanding sensitivity, lithographic fabrication, and large array sizes, especially through the recent development of multiplexing techniques. This paper describes the scientific opportunities, the basic physics of these devices, the techniques for radiation coupling, and reviews the recent progress in direct detectors, such as transition-edge bolometers, and the work on tunnel junction (superconductor-insulator-superconductor) and hot-electron mixers.

K. D. Irwin, Michael D. Niemack, Joern Beyer +7 more

Multiplexed superconducting quantum interference device (SQUID) amplifiers have recently enabled the deployment of kilopixel arrays of superconducting transition-edge sensor (TES) detectors on a variety of receivers for astrophysics. Existing multiplexing techniques for TES arrays, however, have constraints due to aliasing of SQUID noise, the size of the required filtering elements, or the complexity of the room-temperature electronics that make it difficult to scale to much larger arrays. We have developed a Walsh code-division SQUID multiplexer that has the potential to enable the multiplexing of larger arrays or pixels with faster thermal response times. The multiplexer uses superconducting switches to modulate the polarity of coupling between N individual TES detectors and a single output SQUID channel. The polarities of the detector signals are switched in the pattern of an N × N Walsh matrix, so a frame composed of N orthogonal samples can be used to reconstruct the detector signals without degradation. We present an analysis of the circuit architecture and preliminary results.

Pascal Febvre