skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Pseudogap temperature and effects of a harmonic trap in the BCS-BEC crossover regime of an ultracold Fermi gas

Abstract

We theoretically investigate excitation properties in the pseudogap regime of a trapped Fermi gas. Using a combined T-matrix theory with the local density approximation, we calculate strong-coupling corrections to single-particle local density of states (LDOS), as well as the single-particle local spectral weight (LSW). Starting from the superfluid phase transition temperature T{sub c}, we clarify how the pseudogap structures in these quantities disappear with increasing the temperature. As in the case of a uniform Fermi gas, LDOS and LSW give different pseudogap temperatures T{sup *} and T{sup **} at which the pseudogap structures in these quantities completely disappear. Determining T{sup *} and T{sup **} over the entire BCS (Bardeen-Cooper-Schrieffer)-BEC (Bose-Einstein condensation) crossover region, we identify the pseudogap regime in the phase diagram with respect to the temperature and the interaction strength. We also show that the so-called back-bending peak recently observed in the photoemission spectra by the JILA group may be explained as an effect of pseudogap phenomenon in the trap center. Since strong pairing fluctuations, spatial inhomogeneity, and finite temperatures are important keys in considering real cold Fermi gases, our results would be useful for clarifying normal-state properties of this strongly interacting Fermi system.

Authors:
 [1];  [2];  [2]
  1. Department of Physics, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601 (Japan)
  2. Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522 (Japan)
Publication Date:
OSTI Identifier:
22093355
Resource Type:
Journal Article
Journal Name:
Physical Review. A
Additional Journal Information:
Journal Volume: 84; Journal Issue: 4; Other Information: (c) 2011 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1050-2947
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 74 ATOMIC AND MOLECULAR PHYSICS; APPROXIMATIONS; BCS THEORY; BOSE-EINSTEIN CONDENSATION; CORRECTIONS; ENERGY GAP; ENERGY-LEVEL DENSITY; EXCITATION; FERMI GAS; FLUCTUATIONS; PHASE DIAGRAMS; PHASE TRANSFORMATIONS; PHOTOEMISSION; S MATRIX; SUPERFLUIDITY; TRANSITION TEMPERATURE; TRAPPING; TRAPS

Citation Formats

Tsuchiya, Shunji, Research and Education Center for Natural Sciences, Keio University, 4-1-1 Hiyoshi, Kanagawa 223-8521, CREST, Watanabe, Ryota, Ohashi, Yoji, and CREST. Pseudogap temperature and effects of a harmonic trap in the BCS-BEC crossover regime of an ultracold Fermi gas. United States: N. p., 2011. Web. doi:10.1103/PHYSREVA.84.043647.
Tsuchiya, Shunji, Research and Education Center for Natural Sciences, Keio University, 4-1-1 Hiyoshi, Kanagawa 223-8521, CREST, Watanabe, Ryota, Ohashi, Yoji, & CREST. Pseudogap temperature and effects of a harmonic trap in the BCS-BEC crossover regime of an ultracold Fermi gas. United States. https://doi.org/10.1103/PHYSREVA.84.043647
Tsuchiya, Shunji, Research and Education Center for Natural Sciences, Keio University, 4-1-1 Hiyoshi, Kanagawa 223-8521, CREST, Watanabe, Ryota, Ohashi, Yoji, and CREST. Sat . "Pseudogap temperature and effects of a harmonic trap in the BCS-BEC crossover regime of an ultracold Fermi gas". United States. https://doi.org/10.1103/PHYSREVA.84.043647.
@article{osti_22093355,
title = {Pseudogap temperature and effects of a harmonic trap in the BCS-BEC crossover regime of an ultracold Fermi gas},
author = {Tsuchiya, Shunji and Research and Education Center for Natural Sciences, Keio University, 4-1-1 Hiyoshi, Kanagawa 223-8521 and CREST and Watanabe, Ryota and Ohashi, Yoji and CREST},
abstractNote = {We theoretically investigate excitation properties in the pseudogap regime of a trapped Fermi gas. Using a combined T-matrix theory with the local density approximation, we calculate strong-coupling corrections to single-particle local density of states (LDOS), as well as the single-particle local spectral weight (LSW). Starting from the superfluid phase transition temperature T{sub c}, we clarify how the pseudogap structures in these quantities disappear with increasing the temperature. As in the case of a uniform Fermi gas, LDOS and LSW give different pseudogap temperatures T{sup *} and T{sup **} at which the pseudogap structures in these quantities completely disappear. Determining T{sup *} and T{sup **} over the entire BCS (Bardeen-Cooper-Schrieffer)-BEC (Bose-Einstein condensation) crossover region, we identify the pseudogap regime in the phase diagram with respect to the temperature and the interaction strength. We also show that the so-called back-bending peak recently observed in the photoemission spectra by the JILA group may be explained as an effect of pseudogap phenomenon in the trap center. Since strong pairing fluctuations, spatial inhomogeneity, and finite temperatures are important keys in considering real cold Fermi gases, our results would be useful for clarifying normal-state properties of this strongly interacting Fermi system.},
doi = {10.1103/PHYSREVA.84.043647},
url = {https://www.osti.gov/biblio/22093355}, journal = {Physical Review. A},
issn = {1050-2947},
number = 4,
volume = 84,
place = {United States},
year = {2011},
month = {10}
}