Operational Work Fluctuation Theorem for Open Quantum Systems

Area of Science:

• Quantum Thermodynamics
• Statistical Mechanics
• Non-equilibrium Physics

Background:

• The classical Jarzynski equality relates work done on systems out of equilibrium to free energy differences.
• This equality is experimentally valuable for determining free energy via nonequilibrium work measurements.
• Quantum versions of the Jarzynski equality require complex two-point measurements, limiting predictive power.

Purpose of the Study:

• To propose a novel quantum fluctuation theorem for externally measurable quantum work.
• To enable free energy determination in quantum systems without prior knowledge of the Hamiltonian.
• To extend fluctuation theorems to open quantum systems.

Main Methods:

• Developed a quantum fluctuation theorem applicable to work measured during a driving protocol.
• The theorem is valid for open quantum systems and does not require knowledge of the system's Hamiltonian.
• The proposed theorem is formulated as an inequality providing bounds on the free energy difference.

Main Results:

• The proposed quantum fluctuation theorem allows for the determination of bounds on free energy differences.
• The inequality is saturated in the quasiclassical limit, where energy coherences are minimal.
• This work highlights a quantum disadvantage compared to classical systems in this context.

Conclusions:

• The new quantum fluctuation theorem offers a practical approach to studying nonequilibrium quantum thermodynamics.
• It overcomes limitations of previous quantum Jarzynski equality formulations by using externally measurable work.
• The findings underscore the unique challenges and characteristics of quantum systems in thermodynamic processes.