Design, Fabrication and Characterization of Microwave Multiplexing SQUID Prototype

Abstract

The readout system with a high multiplexing ratio has become a bottleneck limiting the application of large-scale Transition Edge Sensor (TES) detector arrays. In recent years, the microwave superconducting quantum interference device (SQUID) multiplexer has emerged as a key technology for effectively reading large-scale cryogenic detector arrays. Currently, the microwave SQUID multiplexer is being adopted by an increasing number of experiments due to its capability of achieving a multiplexing ratio of 2000:1 within the readout bandwidth. In this study, we developed and fabricated a 32-channel microwave SQUID multiplexer prototype. And we measured 8 channels of the prototype. The measured equivalent noise current of the prototype reached 154 pA/$\sqrt{Hz}$.

Figures (10)

• Figure 1: The equivalent electronics schematic diagram of $\mu$Mux.
• Figure 2: (a) Design of $\mu$Mux; (b) Partial microphotograph of the chip; (c) Quarter-wavelength resonator with capacitively coupled to the feedline; (d) RF-SQUID and slotting washer; (e) Flux ramp LR filter (left) and input coil LR filter (right).
• Figure 3: The measured IV curve of a 4$\mu$m $\times$ 4$\mu$m Josephson junction.
• Figure 4: The fabrication procedure of $\mu$Mux.
• Figure 5: Block diagram of $\mu$Mux readout electronics. (a) The cryogenic readout electronics; (b) The room-temperature readout electronics.