Noise-induced quantum-circuit refrigeration

TL;DR

This paper demonstrates a method to control the thermal state of a microwave resonator using noise-driven quantum-circuit refrigeration, enabling potential applications in quantum computing and heat engines.

Contribution

It introduces a novel approach to modulate resonator temperature using artificial thermal noise, advancing quantum refrigeration techniques.

Findings

Artificial thermal noise can thermalize the resonator to a controlled temperature.

Detuning noise frequency reduces damping effects on the resonator.

Effective temperature of the resonator can be lowered from 300 mK to 130 mK.

Abstract

We use a transmon qubit and its dispersively coupled readout resonator to measure the Fock state populations of another microwave resonator, to which we have attached a quantum-circuit refrigerator (QCR). First, we apply noise generated at room temperature to the resonator and show that such noise drive leads to a thermal distribution of the resonator Fock states. Subsequently, we detune the noise frequency band far away from the resonance condition and vary the power of the noise applied on the QCR. We observe that such artificial thermal noise may lead to major damping of a coherent state of the resonator. Importantly, we also demonstrate that the effective temperature of a thermal resonator state can be reduced from roughly 300 mK to 130 mK by the introduction of the artificial thermal noise. These observations pave the way for a purely thermally powered quantum-circuit refrigerator which may unlock the use of waste heat in resetting superconducting qubits in a quantum processor and in building autonomous quantum heat engines.