Analog of a Quantum Heat Engine Using a Single-Spin Qubit.

Area of Science:

• Quantum thermodynamics
• Solid-state physics
• Quantum computing

Background:

• Quantum heat machines offer a pathway to miniaturized thermodynamic devices.
• Understanding quantum systems' thermodynamic behavior is crucial for quantum technologies.

Purpose of the Study:

• To experimentally realize and theoretically describe a minimal universal quantum heat machine.
• To investigate the thermodynamic performance of a quantum two-level system in different regimes.

Main Methods:

• Utilized an impurity electron spin in a silicon tunnel field-effect transistor as a quantum two-level system.
• Employed periodic modulation of the energy splitting to control the system's thermodynamic cycles.
• Analyzed system behavior in both incoherent (Otto engine/refrigerator) and coherent regimes.

Main Results:

• Demonstrated experimental realization of a quantum heat machine based on electron spin.
• Observed analogous behavior to Otto heat engines and refrigerators in the incoherent regime.
• Identified superposition of engine and refrigerator regimes in coherent operation, evidenced by interference fringes in source-drain current.

Conclusions:

• A periodically modulated quantum two-level system serves as a minimal universal quantum heat machine.
• The electron spin in a silicon tunnel field-effect transistor is a viable platform for quantum heat devices.
• Coherent operation introduces unique quantum effects, like interference, impacting machine performance.