Superfluid density of states and pseudogap phenomenon in the BCS-BEC crossover regime of a superfluid Fermi gas

Journal Article · Fri Oct 15 04:00:00 EDT 2010 · Physical Review. A

DOI:https://doi.org/10.1103/PHYSREVA.82.043630· OSTI ID:21454817

Watanabe, Ryota ^[1]; Tsuchiya, Shunji ^[2]; Ohashi, Yoji ^[1]

---

1. Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522 (Japan)
2. Department of Physics, Faculty of Science, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601 (Japan)

We investigate single-particle excitations and strong-coupling effects in the BCS-BEC crossover regime of a superfluid Fermi gas. Including phase and amplitude fluctuations of the superfluid order parameter within a T-matrix theory, we calculate the superfluid density of states (DOS), as well as single-particle spectral weight, over the entire BCS-BEC crossover region below the superfluid transition temperature T{sub c}. We clarify how the pseudogap in the normal state evolves into the superfluid gap, as one passes through T{sub c}. While the pseudogap in DOS continuously evolves into the superfluid gap in the weak-coupling BCS regime, the superfluid gap in the crossover region is shown to appear in DOS after the pseudogap disappears below T{sub c}. In the phase diagram with respect to the temperature and interaction strength, we determine the region where strong pairing fluctuations dominate over single-particle properties of the system. Our results would be useful for the study of strong-coupling phenomena in the BCS-BEC crossover regime of a superfluid Fermi gas.

• OSTI ID: 21454817
• Journal Information: Physical Review. A, Journal Name: Physical Review. A Journal Issue: 4 Vol. 82; ISSN 1050-2947; ISSN PLRAAN
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
AMPLITUDES
BCS THEORY
BOSE-EINSTEIN CONDENSATION
COUPLING
DIAGRAMS
DIMENSIONLESS NUMBERS
ENERGY GAP
ENERGY-LEVEL DENSITY
ENERGY-LEVEL TRANSITIONS
EXCITATION
FERMI GAS
FLUCTUATIONS
INFORMATION
INTERACTIONS
MATRICES
ORDER PARAMETERS
OSCILLATION MODES
PAIRING INTERACTIONS
PHASE DIAGRAMS
PHYSICAL PROPERTIES
S MATRIX
SINGLE-PARTICLE MODES
SUPERFLUIDITY
THERMODYNAMIC PROPERTIES
TRANSITION TEMPERATURE
VARIATIONS