Smoothed generalized free energies for thermodynamics

Journal Article (2017)
Author(s)

Remco Van Der Meer

Nelly Huei Ying Ng (National University of Singapore, TU Delft - Quantum Information and Software)

Stephanie Wehner (TU Delft - Quantum Internet Division, TU Delft - Quantum Information and Software)

Department
Quantum Internet Division
DOI related publication
https://doi.org/10.1103/PhysRevA.96.062135 Final published version
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Publication Year
2017
Language
English
Department
Quantum Internet Division
Journal title
Physical Review A: covering atomic, molecular, and optical physics and quantum information
Issue number
6
Volume number
96
Article number
062135
Pages (from-to)
062135-1 - 062135-18
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255
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Abstract

In the study of thermodynamics for nanoscale quantum systems, a family of quantities known as generalized free energies have been derived as necessary and sufficient conditions that govern state transitions. These free energies become important especially in the regime where the system of interest consists of only a few (quantum) particles. In this work, we introduce a family of smoothed generalized free energies, by constructing explicit smoothing procedures that maximize or minimize the free energy over an ball of quantum states. In contrast to previously known smoothed free energies, these quantities now allow us to make an operational statement for approximate thermodynamic state transitions. We show that these smoothed quantities converge to the standard free energy in the thermodynamic limit.