[7p-S41-1~15] 11.5 Junction and circuit fabrication process, digital applications

[7p-S41-1] [JSAP Young Scientist Award Speech] Demonstration of a 64-ch event-driven SFQ encoder for a single-photon imaging system

〇Shigeyuki Miyajima¹, Masahiro Yabuno¹, Taro Yamashita¹, Shigehito Miki^1,2, Hirotaka Terai¹ (1.NICT, 2.Kobe Univ.)

Keywords:single flux quantum circuit, superconducting single photon detector, imaging system

We demonstrated a 64-ch event-driven encoder based on the single flux quantum (SFQ) circuits for a single-photon imaging system using the superconducting nanowire single photon detectors (SSPDs). In order to reduce the Joule heat in the cables and the SFQ circuits, we designed the SFQ cells with the half critical currents (I_c) of the Josephson junctions (JJs) and half bias voltage to be 1.25 mV. We tested the SFQ-based event-driven encoder in liquid helium and the circuits operated successfully. We also demonstrated the SFQ-based event-driven encoder in a 0.1-W Gifford McMahon (GM) cryocooler. We installed the SFQ-based encoder with 64-pixel SSPDs made of NbTiN in the same cryocooler. The SFQ-based encoder successfully operated by irradiating photons to an SSPD array.