1,558 research outputs found
All-Optical Production of a Degenerate Fermi Gas
We achieve degeneracy in a mixture of the two lowest hyperfine states of
Li by direct evaporation in a CO laser trap, yielding the first
all-optically produced degenerate Fermi gas. More than atoms are
confined at temperatures below K at full trap depth, where the Fermi
temperature for each state is K. This degenerate two-component mixture
is ideal for exploring mechanisms of superconductivity ranging from Cooper
pairing to Bose condensation of strongly bound pairs.Comment: 4 pgs RevTeX with 2 eps figs, to be published in Phys. Rev. Let
Realization of a Resonant Fermi Gas with a Large Effective Range
We have measured the interaction energy and three-body recombination rate for
a two-component Fermi gas near a narrow Feshbach resonance and found both to be
strongly energy dependent. Even for deBroglie wavelengths greatly exceeding the
van der Waals length scale, the behavior of the interaction energy as a
function of temperature cannot be described by atoms interacting via a contact
potential. Rather, energy-dependent corrections beyond the scattering length
approximation are required, indicating a resonance with an anomalously large
effective range. For fields where the molecular state is above threshold, the
rate of three-body recombination is enhanced by a sharp, two-body resonance
arising from the closed-channel molecular state which can be magnetically tuned
through the continuum. This narrow resonance can be used to study strongly
correlated Fermi gases that simultaneously have a sizeable effective range and
a large scattering length.Comment: to appear in Phys. Rev. Let
Phase-field approach to heterogeneous nucleation
We consider the problem of heterogeneous nucleation and growth. The system is
described by a phase field model in which the temperature is included through
thermal noise. We show that this phase field approach is suitable to describe
homogeneous as well as heterogeneous nucleation starting from several general
hypotheses. Thus we can investigate the influence of grain boundaries,
localized impurities, or any general kind of imperfections in a systematic way.
We also put forward the applicability of our model to study other physical
situations such as island formation, amorphous crystallization, or
recrystallization.Comment: 8 pages including 7 figures. Accepted for publication in Physical
Review
Dealing with mobility: Understanding access anytime, anywhere
The rapid and accelerating move towards the adoption and use of mobile technologies has increasingly provided people and organisations with the ability to work away from the office and on the move. The new ways of working afforded by these technologies are often characterised in terms of access to information and people ‘anytime, anywhere’. This paper presents a study of mobile workers that highlights different facets of access to remote people and information, and different facets of anytime, anywhere. Four key factors in mobile work are identified from the study: the role of planning, working in ‘dead time’, accessing remote technological and informational resources, and monitoring the activities of remote colleagues. By reflecting on these issues, we can better understand the role of technology and artefact use in mobile work and identify the opportunities for the development of appropriate technological solutions to support mobile workers
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