Work statistics via real-time effective field theory: Application to work extraction from a thermal bath with qubit...

Area of Science:

• Quantum thermodynamics
• Statistical mechanics
• Condensed matter physics

Background:

• Quantum thermal states are inherently passive, adhering to the second law of thermodynamics.
• Extracting work from these states requires careful consideration of quantum statistics and nonequilibrium processes.

Purpose of the Study:

• Investigate work extraction potential by coupling thermal baths to different qubit types (spin, fermionic, topological).
• Derive work statistics under cyclic nonequilibrium processes to quantify extractable work.
• Develop methods to precisely determine the physical regimes for work extraction.

Main Methods:

• Coupling thermal baths to spin, fermionic, and topological qubits.
• Analyzing work statistics under cyclic nonequilibrium processes.
• Employing an effective field theory approach using quasiparticle operators and thermal spectral functions.

Main Results:

• Derived nonperturbative work distribution function (WDF) for a pure thermal bath.
• Obtained second-order WDF with qubit coupling, enabling precise pinning of work extraction regimes.
• Identified spin and topological qubit-bath systems as yielding superior performance for quantum heat engines/refrigerators.

Conclusions:

• The effective field theory approach provides a tractable method for calculating work statistics in complex quantum systems.
• The developed WDF framework allows for the design and optimization of quantum heat engines and refrigerators.
• Quantum statistics significantly influence the performance of quantum thermal machines, with spin and topological qubits offering advantages.