4,346 research outputs found
Coexistence of pairing gaps in three-component Fermi gases
We study a three-component superfluid Fermi gas in a spherically symmetric
harmonic trap using the Bogoliubov-deGennes method. We predict a coexistence
phase in which two pairing field order parameters are simultaneously nonzero,
in stark contrast to studies performed for trapped gases using local density
approximation. We also discuss the role of atom number conservation in the
context of a homogeneous system.Comment: Text revised, added two figures and three reference
Cooper-pair resonances and subgap Coulomb blockade in a superconducting single-electron transistor
We have fabricated and measured superconducting single-electron transistors
with Al leads and Nb islands. At bias voltages below the gap of Nb we observe
clear signatures of resonant tunneling of Cooper pairs, and of Coulomb blockade
of the subgap currents due to linewidth broadening of the energy levels in the
superconducting density of states of Nb. The experimental results are in good
agreement with numerical simulations.Comment: 4 pages, 3 figure
Evaluation of sensors to monitor the effect of bentonite on the corrosion rate of copper in Olkiluoto-type saline groundwater
Local behavior of p-harmonic Green's functions in metric spaces
We describe the behavior of p-harmonic Green's functions near a singularity
in metric measure spaces equipped with a doubling measure and supporting a
Poincar\'e inequality
Bragg spectroscopy of a strongly interacting Bose-Einstein condensate
We study Bragg spectroscopy of a strongly interacting Bose-Einstein
condensate using time-dependent Hartree-Fock-Bogoliubov theory. We include
approximatively the effect of the momentum dependent scattering amplitude which
is shown to be the dominant factor in determining the spectrum for large
momentum Bragg scattering. The condensation of the Bragg scattered atoms is
shown to significantly alter the observed excitation spectrum by creating a
novel pairing channel of mobile pairs.Comment: 11 pages, 4 figure
Imbalanced Superfluid Phase of a Trapped Fermi Gas in the BCS-BEC Crossover Regime
We theoretically investigate the ground state of trapped neutral fermions
with population imbalance in the BCS-BEC crossover regime. On the basis of the
single-channel Hamiltonian, we perform full numerical calculations of the
Bogoliubov-de Gennes equation coupled with the regularized gap and number
equations. The zero-temperature phase diagram in the crossover regime is
presented, where the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) pairing state
governs the weak-coupling BCS region of a resonance. It is found that the FFLO
oscillation vanishes in the BEC side, in which the system under population
imbalance turns into a phase separation (PS) between locally binding superfluid
and fully polarized spin domains. We also demonstrate numerical calculations
with a large particle number O(10^5), comparable to that observed in recent
experiments. The resulting density profile on a resonance yields the PS, which
is in good agreement with the recent experiments, while the FFLO modulation
exists in the pairing field. It is also proposed that the most favorable
location for the detection of the FFLO oscillation is in the vicinity of the
critical population imbalance in the weak coupling BCS regime, where the
oscillation periodicity becomes much larger than the interparticle spacing.
Finally, we analyze the radio-frequency (RF) spectroscopy in the imbalanced
system. The clear difference in the RF spectroscopy between BCS and BEC sides
reveals the structure of the pairing field and local ``magnetization''.Comment: 16 pages, 13 figures, replaced by the version to appear in J. Phys.
Soc. Jp
- …