2,564 research outputs found
Pairing in a three component Fermi gas
We consider pairing in a three-component gas of degenerate fermions. In
particular, we solve the finite temperature mean-field theory of an interacting
gas for a system where both interaction strengths and fermion masses can be
unequal. At zero temperature we find a a possibility of a quantum phase
transition between states associated with pairing between different pairs of
fermions. On the other hand, finite temperature behavior of the three-component
system reveals some qualitative differences from the two-component gas: for a
range of parameters it is possible to have two different critical temperatures.
The lower one corresponds to a transition between different pairing channels,
while the higher one corresponds to the usual superfluid-normal transition. We
discuss how these phase transitions could be observed in ultracold gases of
fermionic atoms.Comment: 10 pages, 3 figure
Quasi two-dimensional superfluid Fermi gases
We study a quasi two-dimensional superfluid Fermi gas where the confinement
in the third direction is due to a strong harmonic trapping. We investigate the
behavior of such a system when the chemical potential is varied and find strong
modifications of the superfluid properties due to the discrete harmonic
oscillator states. We show that such quasi two-dimensional behavior can be
created and observed with current experimental capabilities.Comment: In response to referee comments, minor changes from the earlier
versio
Dynamical instability and loss of p-band bosons in optical lattices
We study how the bosonic atoms on the excited p-band of an optical lattice
are coupled to the lowest s-band and the 2nd excited d-band. We find that in
some parameter regimes the atom-atom interactions can cause a dynamical
instability of the p-band atoms towards decay to the s- and d-bands.
Furthermore, even when dynamical instability is not expected s- and d-bands can
become substantially populated.Comment: 7 figures, minor changes to the earlier versio
Neighbourhoods and self rated health: a comparison of public sector employees in London and Helsinki
Study objective: Mortality and morbidity vary across neighbourhoods and larger residential areas. Effects of area deprivation on health may vary across countries, because of greater spatial separation of people occupying high and low socioeconomic positions and differences in the provision of local services and facilities. Neighbourhood variations in health and the contribution of residents' characteristics and neighbourhood indicators were compared in London and Helsinki, two settings where inequality and welfare policies differ.Design: Data from two cohorts were used to investigate associations between self rated health and neighbourhood indicators using a multilevel approach.Setting: London and Helsinki.Participants: From the Whitehall II study (London, aged 39-63) and the Helsinki health study (aged 40-60).Main results: Socioeconomic segregation was higher in London than in Helsinki. Age and sex adjusted differences in self rated health between neighbourhoods were also greater in London. Independent of individual socioeconomic position, neighbourhood unemployment, proportion of residents in manual occupations, and proportion of single households were associated with health. In pooled data, residence in a neighbourhood with highest unemployment was associated with an odds ratio of less than good self rated health of 1.51 (95% CI 1.30 to 1.75). High rates of single parenthood were associated with health in London but not in Helsinki.Conclusions: Neighbourhood socioeconomic context was associated with health in both countries, with some evidence of greater neighbourhood effects in London. Greater socioeconomic segregation in London may have emergent effects at the neighbourhood level. Local and national social policies may reduce, or restrict, inequality and segregation between areas
Vortex-line solitons in a periodically modulated Bose gas
We study the nonlinear excitations of a vortex-line in a Bose-Einstein
condensate trapped in a one-dimensional optical lattice. We find that the
classical Euler dynamics of the vortex results in a description of the vortex
line in terms of a (discrete) one-dimensional Gross-Pitaevskii equation, which
allows for both bright and gray soliton solutions. We discuss these solutions
in detail and predict that it is possible to create vortex-line solitons with
current experimental capabilities.Comment: minor changes, updated/corrected references, 4 pages, 3 figure
Alien Registration- Martikainen, Emma P. (Gorham, Cumberland County)
https://digitalmaine.com/alien_docs/31732/thumbnail.jp
Superfluid phases of fermions with hybridized and orbitals
We explore the superfluid phases of a two-component Fermi mixture with
hybridized orbitals in optical lattices. We show that there exists a general
mapping of this system to the Lieb lattice. By using simple multiband models
with hopping between and -orbital states, we show that superfluid order
parameters can have a -phase difference between lattice sites, which is
distinct from the case with hopping between -orbitals. If the population
imbalance between the two spin species is tuned, the superfluid phase may
evolve through various phases due to the interplay between hopping,
interactions and imbalance. We show that the rich behavior is observable in
experimentally realizable systems.Comment: 13 pages, 11 figures. Published versio
Exotic superfluid states of lattice fermions in elongated traps
We present real-space dynamical mean-field theory calculations for
attractively interacting fermions in three-dimensional lattices with elongated
traps. The critical polarization is found to be 0.8, regardless of the trap
elongation. Below the critical polarization, we find unconventional superfluid
structures where the polarized superfluid and
Fulde-Ferrell-Larkin-Ovchinnikov-type states emerge across the entire core
region
- …