1,077 research outputs found
Molecular Fine Structure from Water Window X-rays
Postprint (published version
Collective Oscillations of an Imbalanced Fermi Gas: Axial Compression Modes and Polaron Effective Mass
We investigate the low-lying compression modes of a unitary Fermi gas with
imbalanced spin populations. For low polarization, the strong coupling between
the two spin components leads to a hydrodynamic behavior of the cloud. For
large population imbalance we observe a decoupling of the oscillations of the
two spin components, giving access to the effective mass of the Fermi polaron,
a quasi-particle composed of an impurity dressed by particle-hole pair
excitations in a surrounding Fermi sea. We find , in agreement
with the most recent theoretical predictions.Comment: 4 pages, 4 figures, submitted to PR
Expansion of a lithium gas in the BEC-BCS crossover
We report on experiments in Li Fermi gases near Feshbach resonances. A
broad s-wave resonance is used to form a Bose-Einstein condensate of weakly
bound Li molecules in a crossed optical trap. The measured
molecule-molecule scattering length of nm at 770 G is found
in good agreement with theory. The expansion energy of the cloud in the BEC-BCS
crossover region is measured. Finally we discuss the properties of p-wave
Feshbach resonances observed near 200 Gauss and new s-wave resonances in the
heteronuclear Li- Li mixture.Comment: 10 pages, 3 figures, Proceedings of ICAP 200
Attosecond Streaking in the Water Window: A New Regime of Attosecond Pulse Characterization
We report on the first streaking measurement of water-window attosecond
pulses generated via high harmonic generation, driven by sub-2-cycle,
CEP-stable, 1850 nm laser pulses. Both the central photon energy and the energy
bandwidth far exceed what has been demonstrated thus far, warranting the
investigation of the attosecond streaking technique for the soft X-ray regime
and the limits of the FROGCRAB retrieval algorithm under such conditions. We
also discuss the problem of attochirp compensation and issues regarding much
lower photo-ionization cross sections compared with the XUV in addition to the
fact that several shells of target gases are accessed simultaneously. Based on
our investigation, we caution that the vastly different conditions in the soft
X-ray regime warrant a diligent examination of the fidelity of the measurement
and the retrieval procedure.Comment: 14 Pages, 12 figure
Experimental Study of the BEC-BCS Crossover Region in Lithium 6
We report Bose-Einstein condensation of weakly bound Limolecules in a
crossed optical trap near a Feshbach resonance. We measure a molecule-molecule
scattering length of nm at 770 G, in good agreement with
theory.We study the expansion of the cloud in the BEC-BCS crossoverregion.Comment: 4 pages, 3 figures, submitted to PR
Bose-Einstein condensates in a double well: mean-field chaos and multi-particle entanglement
A recent publication [Phys. Rev. Lett. 100, 140408 (2008)] shows that there
is a relation between mean-field chaos and multi-particle entanglement for BECs
in a periodically shaken double well. 'Schrodinger-cat' like mesoscopic
superpositions in phase-space occur for conditions for which the system
displays mean-field chaos. In the present manuscript, more general
highly-entangled states are investigated. Mean-field chaos accelerates the
emergence of multi-particle entanglement; the boundaries of stable regions are
particularly suited for entanglement generation.Comment: 5 Pages, 5 jpg-figures, to be published in the proceedings of the
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