Heat-machine control by quantum-state preparation: from quantum engines to refrigerators

Area of Science:

• Quantum Thermodynamics
• Statistical Mechanics
• Quantum Optics

Background:

• Prevailing semiclassical descriptions of autonomous heat machines involve external driving.
• A fully quantized treatment is needed to explore quantum state influences on heat machine performance.
• Quantum states are increasingly recognized as potential resources in thermodynamic processes.

Purpose of the Study:

• To provide a fully quantized treatment of self-contained (autonomous) heat machines.
• To explore the dependence of heat engine and refrigerator performance bounds on initial quantum states.
• To investigate work extraction and refrigeration beyond classical limits using quantum resources.

Main Methods:

• Modeling the piston as a quantized harmonic oscillator.
• Utilizing stationary simultaneous interaction of two heat baths with a two-level system coupled to the piston.
• Applying quantum-optical amplifier and dissipation theory, analyzing phase-plane quasiprobability distributions.

Main Results:

• Quantum states act as thermodynamic resources, controlling heat machine efficiency.
• Pistons initialized in coherent states can enable engines to exceed the Carnot bound.
• Pistons initialized in Fock states can allow refrigerators to surpass the Carnot bound.

Conclusions:

• A fully quantized approach reveals quantum states as crucial for advanced thermodynamic performance.
• Initialization of quantum systems in specific states offers a pathway to break classical thermodynamic limits.
• This framework opens new avenues for designing highly efficient quantum heat engines and refrigerators.