87 research outputs found
Magnetically Controlled Exchange Process in an Ultracold Atom-Dimer Mixture
We report on the observation of an elementary exchange process in an
optically trapped ultracold sample of atoms and Feshbach molecules. We can
magnetically control the energetic nature of the process and tune it from
endoergic to exoergic, enabling the observation of a pronounced threshold
behavior. In contrast to relaxation to more deeply bound molecular states, the
exchange process does not lead to trap loss. We find excellent agreement
between our experimental observations and calculations based on the solutions
of three-body Schr\"odinger equation in the adiabatic hyperspherical
representation. The high efficiency of the exchange process is explained by the
halo character of both the initial and final molecular states.Comment: 4 pages, 4 figure
P. FARNÉS SCHERER, Construir y adaptar las Iglesias. Orientaciones y sugerencias prácticas sobre el espacio celebrativo, según el espÃritu del Concilio Vaticano II, Ed. Regina, Barcelona 1989, 272 pp., 13 x 19,5. [RECENSIÓN]
We study the growth of two- and three-body correlations in an ultracold Bose gas quenched to unitarity. This is encoded in the dynamics of the two- and three-body contacts analyzed in this work. Via a set of relations connecting many-body correlations dynamics with few-body models, signatures of the Efimov effect are mapped out as a function of evolution time at unitarity over a range of atomic densities . For the thermal resonantly interacting Bose gas, we find that atom-bunching leads to an enhanced growth of few-body correlations. These atom-bunching effects also highlight the interplay between few-body correlations that occurs before genuine many-body effects enter on Fermi timescales
Observation of an Efimov resonance in an ultracold mixture of atoms and weakly bound dimers
We discuss our recent observation of an atom-dimer Efimov resonance in an
ultracold mixture of Cs atoms and Cs_2 Feshbach molecules [Nature Phys. 5, 227
(2009)]. We review our experimental procedure and present additional data
involving a non-universal g-wave dimer state, to contrast our previous results
on the universal s-wave dimer. We resolve a seeming discrepancy when
quantitatively comparing our experimental findings with theoretical results
from effective field theory.Comment: Conference Proceeding ICPEAC 2009 Kalamazoo, to appear in Journal of
Physics: Conference Serie
Observation of an Efimov resonance in an ultracold mixture of atoms and weakly bound dimers
We discuss our recent observation of an atom-dimer Efimov resonance in an
ultracold mixture of Cs atoms and Cs_2 Feshbach molecules [Nature Phys. 5, 227
(2009)]. We review our experimental procedure and present additional data
involving a non-universal g-wave dimer state, to contrast our previous results
on the universal s-wave dimer. We resolve a seeming discrepancy when
quantitatively comparing our experimental findings with theoretical results
from effective field theory.Comment: Conference Proceeding ICPEAC 2009 Kalamazoo, to appear in Journal of
Physics: Conference Serie
Observation of an Efimov resonance in an ultracold mixture of atoms and weakly bound dimers
We discuss our recent observation of an atom-dimer Efimov resonance in an
ultracold mixture of Cs atoms and Cs_2 Feshbach molecules [Nature Phys. 5, 227
(2009)]. We review our experimental procedure and present additional data
involving a non-universal g-wave dimer state, to contrast our previous results
on the universal s-wave dimer. We resolve a seeming discrepancy when
quantitatively comparing our experimental findings with theoretical results
from effective field theory.Comment: Conference Proceeding ICPEAC 2009 Kalamazoo, to appear in Journal of
Physics: Conference Serie
Density profiles and density oscillations of an interacting three-component normal Fermi gas
We use a semiclassical approximation to investigate density variations and
dipole oscillations of an interacting three-component normal Fermi gas in a
harmonic trap. We consider both attractive and repulsive interactions between
different pairs of fermions and study the effect of population imbalance on
densities. We find that the density profiles significantly deviate from those
of non-interacting profiles and extremely sensitive to interactions and
population imbalance. Unlike for a two-component Fermi system, we find density
imbalance even for balanced populations. For some range of parameters, one
component completely repels from the trap center giving rise a donut shape
density profile. Further, we find that the in-phase dipole oscillation
frequency is consistent with Kohn's theorem and other two dipole mode
frequencies are strongly effected by the interactions and the number of atoms
in the harmonic trap.Comment: Total seven pages with five figures. Published versio
Bunching, clustering, and the buildup of few-body correlations in a quenched unitary Bose gas
We study the growth of two- and three-body correlations in an ultracold Bose gas quenched to unitarity. This is encoded in the dynamics of the two- and three-body contacts analyzed in this work. Via a set of relations connecting many-body correlations dynamics with few-body models, signatures of the Efimov effect are mapped out as a function of evolution time at unitarity over a range of atomic densities . For the thermal resonantly interacting Bose gas, we find that atom-bunching leads to an enhanced growth of few-body correlations. These atom-bunching effects also highlight the interplay between few-body correlations that occurs before genuine many-body effects enter on Fermi timescales
Evidence for Efimov quantum states in an ultracold gas of cesium atoms
Systems of three interacting particles are notorious for their complex
physical behavior. A landmark theoretical result in few-body quantum physics is
Efimov's prediction of a universal set of bound trimer states appearing for
three identical bosons with a resonant two-body interaction.
Counterintuitively, these states even exist in the absence of a corresponding
two-body bound state. Since the formulation of Efimov's problem in the context
of nuclear physics 35 years ago, it has attracted great interest in many areas
of physics. However, the observation of Efimov quantum states has remained an
elusive goal. Here we report the observation of an Efimov resonance in an
ultracold gas of cesium atoms. The resonance occurs in the range of large
negative two-body scattering lengths, arising from the coupling of three free
atoms to an Efimov trimer. Experimentally, we observe its signature as a giant
three-body recombination loss when the strength of the two-body interaction is
varied. We also detect a minimum in the recombination loss for positive
scattering lengths, indicating destructive interference of decay pathways. Our
results confirm central theoretical predictions of Efimov physics and represent
a starting point with which to explore the universal properties of resonantly
interacting few-body systems. While Feshbach resonances have provided the key
to control quantum-mechanical interactions on the two-body level, Efimov
resonances connect ultracold matter to the world of few-body quantum phenomena.Comment: 18 pages, 3 figure
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