Nonequilibrium heat transport and work with a single artificial atom coupled to a waveguide: emission without external driving

Abstract

We observe the continuous emission of photons into a waveguide from a superconducting qubit without the application of an external drive. To explain this observation, we build a two-bath model where the qubit couples simultaneously to a cold bath (the waveguide) and a hot bath (a secondary environment). Our results show that the thermal-photon occupation of the hot bath is up to 0.14 photons, 35 times larger than the cold waveguide, leading to nonequilibrium heat transport with a power of up to 132 zW, as estimated from the qubit emission spectrum. By adding more isolation between the sample output and the first cold amplifier in the output line, the heat transport is strongly suppressed. Our interpretation is that the hot bath may arise from active two-level systems being excited by noise from the output line. We also apply a coherent drive, and use the waveguide to measure thermodynamic work and heat, suggesting waveguide spectroscopy is a useful means to study quantum heat engines and refrigerators. Finally, based on the theoretical model, we propose how a similar setup can be used as a noise spectrometer which provides a new solution for calibrating the background noise of hybrid quantum systems.

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Cited by in corpus (10)

• Energetics of a Single Qubit Gate
• Numerically "exact" simulations of a quantum Carnot cycle: Analysis using thermodynamic work diagrams
• Microwave quantum diode
• Engineering symmetry-selective couplings of a superconducting artificial molecule to microwave waveguides
• Maxwell's two-demon engine under pure dephasing noise
• Asymmetries of thermal processes in open quantum systems
• All-thermal reversal of heat currents using qutrits
• Group delay controlled by the decoherence of a single artificial atom
• Evolution of coherent waves driving a single artificial atom
• Tunable frequency conversion and comb generation with a superconducting artificial atom