Publication
Title
Pseudogap and preformed pairs in the imbalanced Fermi gas in two dimensions
Author
Abstract
The physics of the pseudogap state is intimately linked with the pairing mechanism that gives rise to superfluidity in quantum gases and to superconductivity in high-Tc cuprates, and therefore, both in quantum gases and in superconductors, the pseudogap state and preformed pairs have been under intensive experimental scrutiny. Here, we develop a path integral treatment that provides a divergence-free description of the paired state in two-dimensional Fermi gases. Within this formalism, we derive the pseudogap temperature and the pair fluctuation spectral function, and compare these results with a recent experimental measurement of the pairing in the two-dimensional Fermi gas. The removal of the infrared divergence in the number equations is shown both numerically and analytically, through a study of the long-wavelength and low-energy limit of the pair fluctuation density. Besides the pseudogap temperature, the pair formation temperature and the critical temperature for superfluidity are also derived. The latter corresponds to the BerezinskiKosterlitzThouless (BKT) temperature. The pseudogap temperature, which coincides with the pair formation temperature in the mean field, is found to be suppressed with respect to the pair formation temperature by fluctuations. This suppression is strongest for large binding energies of the pairs. Finally, we investigate how the pair formation temperature, the pseudogap temperature and the BKT temperature behave as a function of both binding energy and imbalance between the pairing partners in the Fermi gas. This allows us to set up phase diagrams for the two-dimensional Fermi gas, in which the superfluid phase, the phase-fluctuating quasicondensate and the normal state can be identified.
Language
English
Source (journal)
New journal of physics / Institute of Physics [Londen]; German Physical Society. - Bristol
Publication
Bristol : 2012
ISSN
1367-2630
DOI
10.1088/1367-2630/14/10/103044
Volume/pages
14 :10 (2012) , 22 p.
Article Reference
103044
ISI
000310439900001
Medium
E-only publicatie
Full text (Publisher's DOI)
Full text (open access)
UAntwerpen
Faculty/Department
Research group
Project info
Dynamic effects in coupled superconductor-ferromagnet nanosystems.
Quantum turbulence in atomic and solid state Bose-Einstein condensates.
Optical confinement phenomena in plasmonic nanomaterials with predesigned electromagnetic properties.
Publication type
Subject
Affiliation
Publications with a UAntwerp address
External links
Web of Science
Record
Identifier
Creation 31.10.2012
Last edited 04.03.2024
To cite this reference