Microwave-Induced Cooling of a Superconducting Qubit

TL;DR

This paper demonstrates microwave-induced cooling in a superconducting flux qubit, achieving significantly lower effective temperatures and offering a new method for qubit-state preparation and decoherence suppression in quantum computing.

Contribution

It introduces a novel microwave-driven cooling technique for superconducting qubits, analogous to optical cooling, enhancing qubit initialization and coherence.

Findings

Achieved effective temperatures as low as 3 millikelvin.

Demonstrated cooling factor between 10 and 100.

Applicable to other solid-state quantum systems.

Abstract

We demonstrated microwave-induced cooling in a superconducting flux qubit. The thermal population in the first-excited state of the qubit is driven to a higher-excited state by way of a sideband transition. Subsequent relaxation into the ground state results in cooling. Effective temperatures as low as Teff~ 3 millikelvin are achieved for bath temperatures Tbath = 30 - 400 millikelvin, a cooling factor between 10 and 100. This demonstration provides an analog to optical cooling of trapped ions and atoms and is generalizable to other solid-state quantum systems. Active cooling of qubits, applied to quantum information science, provides a means for qubit-state preparation with improved fidelity and for suppressing decoherence in multi-qubit systems.