Cryogenic microwave source for qubit read-out

One of the key features required to realize a fault-tolerant scalable quantum computer is the integration of reliable and energy-efficient electronics for qubit control and readout. Recently, qubit control electronics have been successfully integrated using cryogenic CMOS technology [1,2,3] and superconducting Josephson junctions [4]. Compared to those methods, the tunnel-diode circuits have smaller device sizes and lower power dissipation (~1μW).

We present the recent development and experimental results of read-out electronics using a tunnel-diode cryogenic circuit with a tunable generated signal higher than 100 MHz. Thanks to the low power consumption an operating temperature range can be from 4 K to 30 mK. The phase noise was measured to be -20 dBc/Hz at an offset frequency of 10 Hz and -80 dBc/Hz at an offset frequency of 1 MHz. We also show its feasibility to be used for qubit read-out using a test device.

[1] J. P. G. Van Dijk, et al., IEEE J. Solid-State Circuits 55, 2930 (2020).

[2] J. C. Bardin, et al., IEEE J. Solid-State Circuits 54, 3043 (2019).

[3] S. Pauka, et al., Nat. Electron, 4, 64 (2021).

[4] K. L. Howe, et al., PRX Quantum 3, 010350 (2022).