Contributions to single-shot energy exchanges in open quantum systems.

Area of Science:

• Quantum Mechanics
• Thermodynamics
• Statistical Mechanics

Background:

• Classical energy exchange is analyzed via phase-space trajectories for single experiments.
• Quantum energy exchange typically requires an ensemble of experiments and the reduced system density matrix.
• Existing single-shot quantum methods are limited to continuously monitored or weakly coupled systems.

Purpose of the Study:

• To derive an exact formula for the rate of total energy change in open quantum systems.
• To enable single-shot analysis of energy exchange for systems strongly coupled to their environment.
• To identify distinct contributions to energy flow in open quantum systems.

Main Methods:

• Utilizing the concept of the conditional wave function for quantum systems.
• Developing an exact formula applicable to arbitrary system-environment coupling.
• Analyzing energy flow without continuous monitoring or ensemble averaging.

Main Results:

• An exact formula for the rate of total energy change in open quantum systems was derived.
• Three distinct contributions to energy flow were identified: external, interaction, and entanglement.
• The method is valid for systems with arbitrary coupling to the environment.

Conclusions:

• The conditional wave function provides a framework for single-shot energy exchange analysis in strongly coupled open quantum systems.
• The identified energy flow contributions offer new insights into quantum thermodynamics.
• This work opens new experimental avenues for studying energy fluctuations in quantum systems.