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Rotational Properties of Lee-Huang-Yang Bosonic Condensates from One to Two Dimensions

Holmström, Hjalmar LU (2022) FYSK02 20221
Mathematical Physics
Department of Physics
Abstract
This thesis covers the work of a numerical examination of the rotational properties of a two-component Bose-Einstein condensate (BEC) utilizing the beyond mean-field extended Gross-Pitaevskii equation for a specified set of parameters. These parameters are chosen to cancel the strength of the mean-field interaction, which makes the system predominantly governed by the next order beyond the mean-field Lee-Huang-Yang (LHY) term. This type of BEC, referred to as an LHY-fluid, is what will be examined further in this work. The theoretical part shows how this LHY-fluid is produced with the appropriate one and two-dimensional models. These models are then utilized to quantitatively examine the rotational properties of a two-dimensional LHY-fluid... (More)
This thesis covers the work of a numerical examination of the rotational properties of a two-component Bose-Einstein condensate (BEC) utilizing the beyond mean-field extended Gross-Pitaevskii equation for a specified set of parameters. These parameters are chosen to cancel the strength of the mean-field interaction, which makes the system predominantly governed by the next order beyond the mean-field Lee-Huang-Yang (LHY) term. This type of BEC, referred to as an LHY-fluid, is what will be examined further in this work. The theoretical part shows how this LHY-fluid is produced with the appropriate one and two-dimensional models. These models are then utilized to quantitatively examine the rotational properties of a two-dimensional LHY-fluid in harmonic confinement and an LHY-fluid confined on a ring in one and two dimensions. (Less)
Popular Abstract
In the field of ultracold physics, physicists often study a particular state of matter called a Bose-Einstein condensate (BEC). When we cool down a collection of atoms with certain conditions to temperatures very close to absolute zero (-273.15 ◦C), they will eventually change state into a BEC. This type of state behaves very differently from what we are used to in everyday life. For example, one interesting property of liquid BEC is that it behaves like a superfluid, meaning that it flows without resistance. This leads to the rather odd phenomenon which is that If you were to start stirring it, for example in a beaker, it would never stop and would continue to flow indefinitely.

To do experiments with BEC, physicists will often use a... (More)
In the field of ultracold physics, physicists often study a particular state of matter called a Bose-Einstein condensate (BEC). When we cool down a collection of atoms with certain conditions to temperatures very close to absolute zero (-273.15 ◦C), they will eventually change state into a BEC. This type of state behaves very differently from what we are used to in everyday life. For example, one interesting property of liquid BEC is that it behaves like a superfluid, meaning that it flows without resistance. This leads to the rather odd phenomenon which is that If you were to start stirring it, for example in a beaker, it would never stop and would continue to flow indefinitely.

To do experiments with BEC, physicists will often use a “trap” to contain it in a small region of space. A typical BEC using only a single type of atom is unstable and will dissipate once we release it from the trap, in other words, it behaves like a gas. But It has relatively recently been found that it is possible to create liquid droplet BEC when we mix it using two different types of atoms. For such a BEC, if we were to release it from the trap, it would stay self-bound, just like a regular water droplet.

From the theoretical point of view, the two main ways physicists describe how the atoms inside a BEC are interacting with each other are by the so-called “mean-field interaction” and “quantum fluctuations”. The mean-field interaction is just a name for the average effect each atom experiences from all its neighboring atoms. Quantum fluctuation is a purely quantum mechanical phenomenon and usually has a very weak effect on the liquid compared to the mean-field interaction.

Under certain conditions, it is possible to completely cancel the effects of the mean-field interaction such that the BEC is mainly governed by the effects of quantum fluctuations. This type of BEC is what we refer to as a “Lee-Huang-Yang” or “LHY-fluid”. The topic of this thesis is to study how an LHY-fluid behaves when we rotate it. This is numerically simulated on a computer in a one and two-dimensional system to find out how it behaves in certain trapping confinements. (Less)
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author
Holmström, Hjalmar LU
supervisor
organization
course
FYSK02 20221
year
type
M2 - Bachelor Degree
subject
keywords
BEC, Bose-Einstein condensate, quantum fluid, Quantum mechanics, LHY, LHY-fluid, Lee-Huang-Yang, Rotating BEC, BEC droplet
language
English
id
9098603
date added to LUP
2022-09-05 11:36:54
date last changed
2022-09-05 11:36:54
@misc{9098603,
  abstract     = {{This thesis covers the work of a numerical examination of the rotational properties of a two-component Bose-Einstein condensate (BEC) utilizing the beyond mean-field extended Gross-Pitaevskii equation for a specified set of parameters. These parameters are chosen to cancel the strength of the mean-field interaction, which makes the system predominantly governed by the next order beyond the mean-field Lee-Huang-Yang (LHY) term. This type of BEC, referred to as an LHY-fluid, is what will be examined further in this work. The theoretical part shows how this LHY-fluid is produced with the appropriate one and two-dimensional models. These models are then utilized to quantitatively examine the rotational properties of a two-dimensional LHY-fluid in harmonic confinement and an LHY-fluid confined on a ring in one and two dimensions.}},
  author       = {{Holmström, Hjalmar}},
  language     = {{eng}},
  note         = {{Student Paper}},
  title        = {{Rotational Properties of Lee-Huang-Yang Bosonic Condensates from One to Two Dimensions}},
  year         = {{2022}},
}