712 research outputs found
Exciting Collective Oscillations in a Trapped 1D Gas
We report on the realization of a trapped one dimensional Bose gas and its
characterization by means of measuring its lowest lying collective excitations.
The quantum degenerate Bose gas is prepared in a 2D optical lattice and we find
the ratio of the frequencies of the lowest compressional (breathing) mode and
the dipole mode to be , in accordance with the
Lieb-Liniger and mean-field theory. For a thermal gas we measure
. By heating the quantum degenerate gas we have
studied the transition between the two regimes. For the lowest number of
particles attainable in the experiment the kinetic energy of the system is
similar to the interaction energy and we enter the strongly interacting regime.Comment: 4 pages, 4 figure
Conclusions and perspectives: Perspectives for future research-and-development projects on biological
The review of published scientific literature on the biological control of selected pests and diseases has lead to the identification of clear knowledge gaps highlighted in previous chapters. Further bottlenecks were revealed by seeking the possible reasons for the striking discrepancy between the rich inventory of potential biocontrol agents described by scientists and a very small number of commercial products on the market. To complement these analyses, the participants of Research Activity 4.3 of the European Network ENDURE organized consultations of experts (scientists, extension specialists and representatives of the Biocontrol industry) at the occasion of scientific meetings of three Working Groups of IOBC-wpr
Detecting multi-atomic composite states in optical lattices
We propose and discuss methods for detecting quasi-molecular complexes which
are expected to form in strongly interacting optical lattice systems.
Particular emphasis is placed on the detection of composite fermions forming in
Bose-Fermi mixtures. We argue that, as an indirect indication of the composite
fermions and a generic consequence of strong interactions, periodic
correlations must appear in the atom shot noise of bosonic absorption images,
similar to the bosonic Mott insulator [S. F\"olling, et al., Nature {\bf 434},
481 (2005)]. The composites can also be detected directly and their
quasi-momentum distribution measured. This method -- an extension of the
technique of noise correlation interferometry [E. Altman et al., Phys. Rev. A
{\bf 79}, 013603 (2004)] -- relies on measuring higher order correlations
between the bosonic and fermionic shot noise in the absorption images. However,
it fails for complexes consisting of more than three atoms.Comment: 9 revtex page
Decoherence of a single-ion qubit immersed in a spin-polarized atomic bath
We report on the immersion of a spin-qubit encoded in a single trapped ion
into a spin-polarized neutral atom environment, which possesses both continuous
(motional) and discrete (spin) degrees of freedom. The environment offers the
possibility of a precise microscopic description, which allows us to understand
dynamics and decoherence from first principles. We observe the spin dynamics of
the qubit and measure the decoherence times (T1 and T2), which are determined
by the spin-exchange interaction as well as by an unexpectedly strong
spin-nonconserving coupling mechanism
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