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Microwave-Induced Cooling of a Superconducting Qubit

S. O. Valenzuela·W. D. Oliver·D. M. Berns·K. K. Berggren·L. S. Levitov·T. P. Orlando
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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.

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S. O. Valenzuela, W. D. Oliver, D. M. Berns, K. K. Berggren, L. S. Levitov, T. P. Orlando. 2007-02-08. Microwave-Induced Cooling of a Superconducting Qubit. https://doi.org/10.1126/science.1134008

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