Polarons and molecules in a two-dimensional Fermi gas

Sascha Zöllner; Georg Morten Bruun; C. J. Pethick

doi:10.1103/PhysRevA.83.021603

Polarons and molecules in a two-dimensional Fermi gas

Sascha Zöllner, Georg Morten Bruun, C. J. Pethick

49 Citations (Scopus)

Abstract

We study an impurity atom in a two-dimensional Fermi gas using variational wave functions for (i) an impurity dressed by particle-hole excitations (polaron) and (ii) a dimer consisting of the impurity and a majority atom. In contrast to three dimensions, where similar calculations predict a sharp transition to a dimer state with increasing interspecies attraction, we show that the polaron Ansatz always gives a lower energy. However, the exact solution for a heavy impurity reveals that both a two-body bound state and distortions of the Fermi sea are crucial. This reflects the importance of particle-hole pairs in lower dimensions and makes simple variational calculations unreliable. We show that the energy of an impurity gives important information about its dressing cloud, for which both Ansätze give inaccurate results.

Original language	English
Journal	Physical Review A (Atomic, Molecular and Optical Physics)
Volume	83
Issue number	2
Pages (from-to)	021603(R)
Number of pages	4
ISSN	2469-9926
DOIs	https://doi.org/10.1103/PhysRevA.83.021603
Publication status	Published - 18 Feb 2011

Access to Document

10.1103/PhysRevA.83.021603

http://link.aps.org/doi/10.1103/PhysRevA.83.021603

Cite this

@article{17857fd90c8f4e24a3256f0502e58b05,

title = "Polarons and molecules in a two-dimensional Fermi gas",

abstract = "We study an impurity atom in a two-dimensional Fermi gas using variational wave functions for (i) an impurity dressed by particle-hole excitations (polaron) and (ii) a dimer consisting of the impurity and a majority atom. In contrast to three dimensions, where similar calculations predict a sharp transition to a dimer state with increasing interspecies attraction, we show that the polaron Ansatz always gives a lower energy. However, the exact solution for a heavy impurity reveals that both a two-body bound state and distortions of the Fermi sea are crucial. This reflects the importance of particle-hole pairs in lower dimensions and makes simple variational calculations unreliable. We show that the energy of an impurity gives important information about its dressing cloud, for which both Ans{\"a}tze give inaccurate results.",

author = "Sascha Z{\"o}llner and Bruun, {Georg Morten} and Pethick, {C. J.}",

year = "2011",

month = feb,

day = "18",

doi = "10.1103/PhysRevA.83.021603",

language = "English",

volume = "83",

pages = "021603(R)",

journal = "Physical Review A - Atomic, Molecular, and Optical Physics",

issn = "2469-9926",

publisher = "American Physical Society",

number = "2",

}

TY - JOUR

T1 - Polarons and molecules in a two-dimensional Fermi gas

AU - Zöllner, Sascha

AU - Bruun, Georg Morten

AU - Pethick, C. J.

PY - 2011/2/18

Y1 - 2011/2/18

N2 - We study an impurity atom in a two-dimensional Fermi gas using variational wave functions for (i) an impurity dressed by particle-hole excitations (polaron) and (ii) a dimer consisting of the impurity and a majority atom. In contrast to three dimensions, where similar calculations predict a sharp transition to a dimer state with increasing interspecies attraction, we show that the polaron Ansatz always gives a lower energy. However, the exact solution for a heavy impurity reveals that both a two-body bound state and distortions of the Fermi sea are crucial. This reflects the importance of particle-hole pairs in lower dimensions and makes simple variational calculations unreliable. We show that the energy of an impurity gives important information about its dressing cloud, for which both Ansätze give inaccurate results.

AB - We study an impurity atom in a two-dimensional Fermi gas using variational wave functions for (i) an impurity dressed by particle-hole excitations (polaron) and (ii) a dimer consisting of the impurity and a majority atom. In contrast to three dimensions, where similar calculations predict a sharp transition to a dimer state with increasing interspecies attraction, we show that the polaron Ansatz always gives a lower energy. However, the exact solution for a heavy impurity reveals that both a two-body bound state and distortions of the Fermi sea are crucial. This reflects the importance of particle-hole pairs in lower dimensions and makes simple variational calculations unreliable. We show that the energy of an impurity gives important information about its dressing cloud, for which both Ansätze give inaccurate results.

U2 - 10.1103/PhysRevA.83.021603

DO - 10.1103/PhysRevA.83.021603

M3 - Journal article

SN - 2469-9926

VL - 83

SP - 021603(R)

JO - Physical Review A - Atomic, Molecular, and Optical Physics

JF - Physical Review A - Atomic, Molecular, and Optical Physics

IS - 2

ER -

Polarons and molecules in a two-dimensional Fermi gas

Abstract

Access to Document

Fingerprint

Cite this