Initial demonstration of a quantum heat engine based on dissipation-engineered superconducting circuits.

Area of Science:

• Quantum Thermodynamics
• Superconducting Circuits
• Quantum Information Science

Background:

• Quantum heat engines require precise control over thermal reservoirs and quantum working media.
• Superconducting circuits offer precise engineering of quantum systems but haven't been used for cyclic quantum heat engines.
• Experimental realization of cyclic quantum heat engines is crucial for advancing quantum thermodynamics.

Purpose of the Study:

• To experimentally demonstrate a cyclic quantum heat engine using superconducting circuits.
• To utilize a quantum-circuit refrigerator as a tunable heat reservoir and a transmon qubit as the working medium.
• To investigate the performance (power and efficiency) of quantum Otto cycles in a superconducting circuit system.

Main Methods:

• Implemented a quantum heat engine using a flux-tunable transmon qubit as the working medium.
• Employed a quantum-circuit refrigerator as a tunable heat reservoir.
• Performed quantum Otto cycles with tailored reservoir drive for cooling/heating and flux ramps for qubit frequency control.
• Utilized single-shot qubit readout to monitor qubit state evolution.

Main Results:

• Successfully demonstrated a cyclic quantum heat engine with superconducting circuits.
• Measured positive output powers and efficiencies, consistent with theoretical simulations.
• Verified thermodynamic models for quantum heat engines.
• Showcased advanced control over thermal environments at the quantum level.

Conclusions:

• The experimental realization of a cyclic quantum heat engine using superconducting circuits is achieved.
• Results validate thermodynamic models and demonstrate control over quantum thermal environments.
• This work opens new avenues for exploring quantum advantages in thermodynamics and energy applications.