We present a quantum heat switch based on coupled superconducting qubits, connected to two LC resonators that are terminated by resistors providing two heat baths. To describe the systemwe use a standard second order master equation with respect to coupling to the baths. We find that this system can act as an efficient heat switch controlled by the applied magnetic flux. The flux influences the energy level separations of the system, and under some conditions, the finite coupling of the qubits enhances the transmitted power between the two baths, by an order of magnitude under realistic conditions. At the same time, the bandwidth at maximum power of the switch formed of the coupled qubits is narrowed.
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 ϵ, as compared to that of an ideal Otto cycle. Quantum coherent effects lead invariably to decrease in both cooling power and ϵ 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.