Characterizing Superconducting Resonators in an Autonomous Quantum Heat Engine

Abstract

Quantum heat engines are novel technologies that leverage quantum mechanical principles alongside thermodynamic theory to generate useful work. While experimental realizations of such devices have existed since the 1950s, they require continuous drive by an external control field. Autonomous quantum heat engines offer an alternate approach where the heat engine cycle is driven from within the device itself. Without being superimposed onto an external control field, the generated work from an autonomous quantum heat engine can more easily be observed and extracted. This thesis studies the low-frequency, energy-storing resonator in a superconducting circuit sample proposed as one such autonomous quantum heat engine. Transmission line measurements are performed to characterize the resonator while also analyzing its behavior in the time domain. When thermal-like noise is introduced to the system, the resonance dip is enhanced by up to 4.5 dB. However, the resonator rapidly decays, exhibiting bare resonance behavior after 6 µs without noise. Furthermore, this thesis finds that the intrinsic dissipation rate of the resonator is greater than the photon generation rate of the system. The internal quality factor peaks at 2.1×10^4, higher than the expected values for the type of resonator utilized and four times higher than the bare noiseless resonance. The total quality factor reaches 1.8×10^4 at ideal noise temperatures.