39 research outputs found
Magnetic field control of elastic scattering in a cold gas of fermionic lithium atoms
We study elastic collisions in an optically trapped spin mixture of fermionic
lithium atoms in the presence of magnetic fields up to 1.5kG by measuring
evaporative loss. Our experiments confirm the expected magnetic tunability of
the scattering length by showing the main features of elastic scattering
according to recent calculations. We measure the zero crossing of the
scattering length that is associated with a predicted Feshbach resonance at
530(3)G. Beyond the resonance we observe the expected large cross section in
the triplet scattering regime
Pure Gas of Optically Trapped Molecules Created from Fermionic Atoms
We report on the production of a pure sample of up to 3x10^5 optically
trapped molecules from a Fermi gas of 6Li atoms. The dimers are formed by
three-body recombination near a Feshbach resonance. For purification a
Stern-Gerlach selection technique is used that efficiently removes all trapped
atoms from the atom-molecule mixture. The behavior of the purified molecular
sample shows a striking dependence on the applied magnetic field. For very
weakly bound molecules near the Feshbach resonance, the gas exhibits a
remarkable stability with respect to collisional decay.Comment: 4 pages, 5 figure
Feshbach resonances in the 6Li-40K Fermi-Fermi mixture: Elastic versus inelastic interactions
We present a detailed theoretical and experimental study of Feshbach
resonances in the 6Li-40K mixture. Particular attention is given to the
inelastic scattering properties, which have not been considered before. As an
important example, we thoroughly investigate both elastic and inelastic
scattering properties of a resonance that occurs near 155 G. Our theoretical
predictions based on a coupled channels calculation are found in excellent
agreement with the experimental results. We also present theoretical results on
the molecular state that underlies the 155G resonance, in particular concerning
its lifetime against spontaneous dissociation. We then present a survey of
resonances in the system, fully characterizing the corresponding elastic and
inelastic scattering properties. This provides the essential information to
identify optimum resonances for applications relying on interaction control in
this Fermi-Fermi mixture.Comment: Submitted to EPJD, EuroQUAM special issues "Cold Quantum Matter -
Achievements and Prospects", v2 with updated calibration of magnetic field
(+4mG correction) and updated figures 4 and
Ultra-cold Polarized Fermi Gases
Recent experiments with ultra-cold atoms have demonstrated the possibility of
realizing experimentally fermionic superfluids with imbalanced spin
populations. We discuss how these developments have shed a new light on a half-
century old open problem in condensed matter physics, and raised new
interrogations of their own.Comment: 27 pages; 8 figures; Published in Report in Rep. Prog. Phys. 73
112401 (2010
Exploring an ultracold Fermi-Fermi mixture: Interspecies Feshbach resonances and scattering properties of 6Li and 40K
We report on the observation of Feshbach resonances in an ultracold mixture
of two fermionic species, 6Li and 40K. The experimental data are interpreted
using a simple asymptotic bound state model and full coupled channels
calculations. This unambiguously assigns the observed resonances in terms of
various s- and p-wave molecular states and fully characterizes the ground-state
scattering properties in any combination of spin states.Comment: 4 pages, 4 figures, 1 tabl
The combination of lactate and bicarbonate buffers in continuous venovenous hemodiafiltration and its impact on serum lactate levels and homeostasis
Effect of high-dose selenium substitution on selected laboratory parameters and prognosis in critically ill patients
(En)Countering Epistemic Imperialism:A Critique of ‘Westsplaining’ and Coloniality in Dominant Debates on Russia’s Invasion of Ukraine
On February 24, 2022, the world was surprised by Russia’s full-scale invasion of Ukraine and, perhaps even more so, by Ukraine’s fierce resistance to it. In this article, we examine mainstream and feminist IR debates that have emerged in response to Russia’s invasion, as well as the older debates revived through them. Building on decolonial and feminist scholarship, prominently centering feminist debates from Europe’s East and Central Asia, we argue that dominant Western IR debates on Russia and Ukraine are shaped by inter-imperiality. We trace issues of epistemic injustice, epistemic imperialism and coloniality of knowledge production in mainstream IR and see them replicated in feminist debates, including from the global South perspectives. We conclude with a contemplation on the structural changes warranted across academia to eliminate the coloniality of knowledge production about Ukraine and fellow societies and Indigenous nations affected by Russian colonial and imperial violence