Recent Developments in Quantum‐Circuit Refrigeration

We review the recent progress in direct active cooling of quantum-electric degrees freedom engineered circuits, or quantum-circuit refrigeration. In 2017, invention a refrigerator (QCR) based on photon-assisted tunneling quasiparticles through normal-metal--insulator--superconductor junction inspired series experimental studies demonstrating following main properties: (i) direct-current (dc) bias voltage can change QCR-induced damping rate superconducting microwave resonator by orders magnitude and give rise to non-trivial Lamb shifts, (ii) be controlled nanosecond time scales, (iii) dc replaced excitation, amplitude which controls induced rate. Theoretically, it is predicted that state-of-the-art resonators qubits reset with an infidelity lower than $10^{-4}$ tens nanoseconds using experimentally feasible parameters. A QCR-equipped has also been demonstrated as incoherent photon source output temperature above one kelvin yet operating at millikelvin. This used calibrate cryogenic amplification chains. future, QCR may quickly qubits, hence assist great challenge building practical quantum computer.