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Comment on "Fluctuations in Extractable Work Bound the Charging Power of Quantum Batteries"
Stefano Cusumano1, Łukasz Rudnicki1,2
1International Centre for Theory of Quantum Technologies, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland.
Physical Review Letters
|July 23, 2021
Summary
The extractable work rate changes even if the battery state is a free energy eigenstate, contrary to previous findings. This occurs when the battery undergoes non-unitary dynamics, impacting energy extraction theories.
Area of Science:
- Thermodynamics
- Quantum Mechanics
- Statistical Mechanics
Background:
- The extractable work rate is crucial for understanding energy transformations in quantum systems.
- A previous study suggested that a non-zero extractable work rate requires the battery state not to be an eigenstate of the free energy operator.
Purpose of the Study:
- To investigate the validity of the free energy operator eigenstate condition for extractable work under non-unitary dynamics.
- To re-evaluate the relationship between battery states and energy extraction rates in open quantum systems.
Main Methods:
- Analysis of quantum battery dynamics under non-unitary evolution.
- Theoretical examination of the free energy operator and its eigenstates.
- Comparison of results with existing literature, specifically Phys. Rev. Lett. 125, 040601 (2020).
Main Results:
- The conclusion that a non-zero rate of change of extractable work necessitates the battery state not being a free energy eigenstate does not hold under non-unitary dynamics.
- Non-unitary processes allow for a non-zero extractable work rate even when the battery state is an eigenstate of the free energy operator.
Conclusions:
- The condition for a non-zero extractable work rate needs refinement when considering non-unitary quantum dynamics.
- This finding challenges established theoretical frameworks for energy extraction in open quantum systems.
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