Trends in Low-Temperature Circuit Technology to Control Quantum Bits for Large-Scale Quantum Computers

Recently the number of integrated superconductor qubits and the fidelity in the qubit control are rapidly advanced. Besides the quantum supremacy, which is a remarkable milestone for realizing a large-scale quantum computer, was verified. However, for further increase in the scale of the quantum computer, control circuits to manipulate and read out the qubit state at low temperatures are indispensable to reduce the number of wires connecting the qubits at low temperatures with electronics at room temperature. In this report, recent research activities on qubit control circuits operating at low temperatures are reviewed. © 2021 The Institute of Electrical Engineers of Japan.