On the ergotropy, practical-viability, and dissipation characterization of an electron-phonon quantum battery.
(2026) FYSK04 20252Mathematical Physics
Department of Physics
- Abstract
- This thesis investigates the ergotropy and usability of a certain quantum battery. The ergotropy is the maximum extractable energy of a cyclic process. First, the battery from a previous thesis is recreated and then this battery is investigated in terms of its ergotropy. The battery is proven to not only be charging but also have an equal increase in ergotropy, hence all of the charged energy is usable. This outcome pertains to a system that is closed, and thus not subject to dissipation. In the second part of the thesis a bath is added to the description, to qualitatively address the case of a more realistic battery where dissipation is present. With this dissipation it is shown that the charging of the battery insulates the battery from... (More)
- This thesis investigates the ergotropy and usability of a certain quantum battery. The ergotropy is the maximum extractable energy of a cyclic process. First, the battery from a previous thesis is recreated and then this battery is investigated in terms of its ergotropy. The battery is proven to not only be charging but also have an equal increase in ergotropy, hence all of the charged energy is usable. This outcome pertains to a system that is closed, and thus not subject to dissipation. In the second part of the thesis a bath is added to the description, to qualitatively address the case of a more realistic battery where dissipation is present. With this dissipation it is shown that the charging of the battery insulates the battery from dissipation with the same
bath. Finally, a summary of the results of this work is presented, together with an outlook about possible future investigations. (Less) - Popular Abstract
- Around 50 years ago the physicists of that time could only experiment on naturally existing quantum systems and did not have the ability to build any quantum systems. This limitation has over time been overcome. Also, recently the creation of ever smaller computers, which allows them to be more powerful, has become difficult because of quantum mechanical effects. These both encourage and enable us to build new quantum machine components to overcome this limit. This thesis investigates a specific quantum system to see if it can function as a battery. If true, this could allow for smaller computer components and machines by using quantum mechanics as a starting point. The fact that quantum system can, today, be created in laboratories makes... (More)
- Around 50 years ago the physicists of that time could only experiment on naturally existing quantum systems and did not have the ability to build any quantum systems. This limitation has over time been overcome. Also, recently the creation of ever smaller computers, which allows them to be more powerful, has become difficult because of quantum mechanical effects. These both encourage and enable us to build new quantum machine components to overcome this limit. This thesis investigates a specific quantum system to see if it can function as a battery. If true, this could allow for smaller computer components and machines by using quantum mechanics as a starting point. The fact that quantum system can, today, be created in laboratories makes it useful to characterize different quantum systems through computer simulations.
Quantum batteries are the heart of quantum machines. Without the storage of energy there would be limitations on the types of quantum machines. Normal “classical” computers, for example, use small local batteries in its circuits to make computations possible; To build fully quantum computers one could expect quantum batteries to be useful. Because of this, it isn’t hard to believe it to be essential to create working quantum batteries.
In order for this battery to function as a source of energy, there has to exist available extractable work after charging. Some energy is normally not usable according to the laws of thermodynamics. Loosely speaking, diffused energy is not usable energy. This ties in to the idea of entropy always increasing. In the first major part of this thesis In this thesis we prove that when this quantum battery is charged it actually is charged not only with energy but also with usable energy. The fact that the energy of the battery is useful is of course essential for a battery to be viable as the energy of the battery is supposed to, loosely speaking, make things happen.
The result that we get is very promising. In fact, we find that all of the energy charged is useful energy making the system a perfect battery without any waste or inefficiency. This is, however, only a consequence of the isolation of the system in our simulation. If this was a real system, it might have some loss of energy due to connections to the outside, and this lost energy would not return easily, this concept being called dissipation, and hence the battery might not be as efficient.
In the second major part of the thesis, we investigated precisely this effect of dissipation. We found that for some types of dissipation, the act of charging the battery changes the state of the battery in some way causing the charged battery to be insulated against this same dissipation. This shows that the battery can store energy over time. This section might advise further research.
We conclude that nothing in this work has been found to disqualify this quantum system to be used as a battery. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/9220773
- author
- Steen, Arvid LU
- supervisor
- organization
- course
- FYSK04 20252
- year
- 2026
- type
- M2 - Bachelor Degree
- subject
- keywords
- QTD Quantum Thermodynamics Hubbard-Holstein Hubbard Holstein dimer Suzuki-Trotter ST Exact diagonalization ED Battery Quantum battery Ergotropy Dissipation CL dissipation Caldeira-Leggett Verlet algorithm
- language
- English
- id
- 9220773
- date added to LUP
- 2026-02-16 08:43:01
- date last changed
- 2026-02-16 08:43:01
@misc{9220773,
abstract = {{This thesis investigates the ergotropy and usability of a certain quantum battery. The ergotropy is the maximum extractable energy of a cyclic process. First, the battery from a previous thesis is recreated and then this battery is investigated in terms of its ergotropy. The battery is proven to not only be charging but also have an equal increase in ergotropy, hence all of the charged energy is usable. This outcome pertains to a system that is closed, and thus not subject to dissipation. In the second part of the thesis a bath is added to the description, to qualitatively address the case of a more realistic battery where dissipation is present. With this dissipation it is shown that the charging of the battery insulates the battery from dissipation with the same
bath. Finally, a summary of the results of this work is presented, together with an outlook about possible future investigations.}},
author = {{Steen, Arvid}},
language = {{eng}},
note = {{Student Paper}},
title = {{On the ergotropy, practical-viability, and dissipation characterization of an electron-phonon quantum battery.}},
year = {{2026}},
}