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Entanglement in a quantum heat engine

Öhrn, Harald LU (2020) FYSK02 20201
Mathematical Physics
Department of Physics
Abstract
In 2015 Jonatan Bohr Brask et al. showed that steady-state entanglement could be generated in two interacting qubits incoherently coupled to thermal baths of different temperatures [1]. This thesis is an attempt to re-evaluate their findings with the hope that a slightly different approach and system can help further our understanding of this not yet well understood phenomena. A Lindblad master equation approach is taken to study a two-qubit thermal machine interacting with bosonic thermal reservoirs. It is found that the steady-state entanglement behaves similarly using the Lindblad approach, the main difference being that a larger amount of entanglement can be generated than initially found in Ref. [1].
Popular Abstract
Heat engines are an integral part of modern society and have been since the industrial revolution. Simply speaking, they are machines that convert heat into work. From the early steam engines to the turbines in a nuclear power plant they have powered civilization. Because of this, it is only natural that we would seek the limits of these machines, how big, efficient and reliable can they become? These are all very important questions that have been studied for a long time within the fields of mechanical engineering and thermodynamics. There is one question in particular where classical thermodynamics is no longer enough, it is one posed by physicists all over the world, in all manner of subjects; what happens when it becomes really, really... (More)
Heat engines are an integral part of modern society and have been since the industrial revolution. Simply speaking, they are machines that convert heat into work. From the early steam engines to the turbines in a nuclear power plant they have powered civilization. Because of this, it is only natural that we would seek the limits of these machines, how big, efficient and reliable can they become? These are all very important questions that have been studied for a long time within the fields of mechanical engineering and thermodynamics. There is one question in particular where classical thermodynamics is no longer enough, it is one posed by physicists all over the world, in all manner of subjects; what happens when it becomes really, really small?

It tuns out that it is possible to make heat engines truly microscopic. At this size classical thermodynamics can no longer properly describe the system. We must turn to quantum mechanics to fully understand them. There are many motivations to why quantum mechanics is needed. The most relevant reason is that quantum mechanics describe phenomena that have no counterpart in classical physics. The most famous of which is quantum entanglement. In short, entanglement correlates particles in such a way that if one particle is measured it changes the state of the other entangled particles, no matter how far apart they are at the time. It is entanglement within these microscopic engines that is the topic of this work.

In 2015 a group of physicists showed that entanglement could be generated in a quantum heat engine without any form of external control [Jonatan Bohr Brask et al. New J. Phys. 17 (2015)]. This means that entanglement is generated solely from the temperature difference that drives the engine. This has the potential of being very usefully, as access to entangled states are vital for applications such as quantum teleportation and quantum computing. In this project, an identical system is analyzed by applying a different method. It is found that the generated entanglement can be stronger than originally suspected, provided that the right conditions are met. (Less)
Please use this url to cite or link to this publication:
author
Öhrn, Harald LU
supervisor
organization
course
FYSK02 20201
year
type
M2 - Bachelor Degree
subject
keywords
Quantum physics, Entanglement, Quantum heat engine
language
English
id
9025049
date added to LUP
2020-07-14 18:12:28
date last changed
2020-07-14 18:12:28
@misc{9025049,
  abstract     = {{In 2015 Jonatan Bohr Brask et al. showed that steady-state entanglement could be generated in two interacting qubits incoherently coupled to thermal baths of different temperatures [1]. This thesis is an attempt to re-evaluate their findings with the hope that a slightly different approach and system can help further our understanding of this not yet well understood phenomena. A Lindblad master equation approach is taken to study a two-qubit thermal machine interacting with bosonic thermal reservoirs. It is found that the steady-state entanglement behaves similarly using the Lindblad approach, the main difference being that a larger amount of entanglement can be generated than initially found in Ref. [1].}},
  author       = {{Öhrn, Harald}},
  language     = {{eng}},
  note         = {{Student Paper}},
  title        = {{Entanglement in a quantum heat engine}},
  year         = {{2020}},
}