A Cryogenic CMOS Current Comparator for Spin Qubit Readout Achieving Fast Readout Time and High Current Resolution.

Employing a precise current readout circuit enabled by a current integrator and correlation double sampling circuit, we propose a cryo-CMOS current comparator circuit to readout spin qubit states by a charge sensing scheme. The reduced readout time by a factor of 1/100 and 100-times better current resolution with the readout fidelity of 99.9% compared to the conventional readout systems are achieved. Furthermore, the proposed current comparator attains the best figure-of-merit (FoM) among the conventional cryogenic current readout circuits. This is the demonstration that cryo-CMOS technology can enhance the performance of quantum computer systems.