Otto refrigerator based on a superconducting qubit: classical and quantum performance

TL;DR

This paper analyzes a superconducting qubit-based quantum Otto refrigerator, exploring different operational regimes, quantum effects, and optimized driving waveforms to enhance cooling performance and efficiency.

Contribution

It introduces a detailed analysis of a superconducting qubit Otto refrigerator, highlighting quantum effects, various operational regimes, and waveform optimization for improved performance.

Findings

Cooling power is quadratic in frequency in the nearly adiabatic regime.

Quantum coherence reduces cooling power and efficiency compared to classical dynamics.

Optimized waveforms like truncated trapezoidal drive improve cooling power and efficiency.

Abstract

We analyse a quantum Otto refrigerator based on a superconducting qubit coupled to two LC-resonators each including a resistor acting as a reservoir. We find various operation regimes: nearly adiabatic (low driving frequency), ideal Otto cycle (intermediate frequency), and non-adiabatic coherent regime (high frequency). In the nearly adiabatic regime, the cooling power is quadratic in frequency, and we find substantially enhanced coefficient of performance $\epsilon$, as compared to that of an ideal Otto cycle. Quantum coherent effects lead invariably to decrease in both cooling power and $\epsilon$ as compared to purely classical dynamics. In the non-adiabatic regime we observe strong coherent oscillations of the cooling power as a function of frequency. We investigate various driving waveforms: compared to the standard sinusoidal drive, truncated trapezoidal drive with optimized rise and dwell times yields higher cooling power and efficiency.