8 research outputs found
Quantum-noise quenching in atomic tweezers
The efficiency of extracting single atoms or molecules from an ultracold
bosonic reservoir is theoretically investigated for a protocol based on lasers,
coupling the hyperfine state in which the atoms form a condensate to another
stable state, in which the atom experiences a tight potential in the regime of
collisional blockade, the quantum tweezers. The transfer efficiency into the
single-atom ground state of the tight trap is fundamentally limited by the
collective modes of the condensate, which are thermally and dynamically
excited. The noise due to these excitations can be quenched for sufficiently
long laser pulses, thereby achieving high efficiencies. These results show that
this protocol can be applied for initializing a quantum register based on
tweezer traps for neutral atoms.Comment: 4+ pages, 3 figures, revised version. To appear in Phys. Rev. A
(Rapid
Extracting Atoms on Demand with Lasers
We propose a scheme that allows to coherently extract cold atoms from a
reservoir in a deterministic way. The transfer is achieved by means of
radiation pulses coupling two atomic states which are object to different
trapping conditions. A particular realization is proposed, where one state has
zero magnetic moment and is confined by a dipole trap, whereas the other state
with non-vanishing magnetic moment is confined by a steep microtrap potential.
We show that in this setup a predetermined number of atoms can be transferred
from a reservoir, a Bose-Einstein condensate, into the collective quantum state
of the steep trap with high efficiency in the parameter regime of present
experiments.Comment: 11 pages, 8 figure
Quantum coherence and interaction-free measurements
We investigate the extent to which ``interaction-free'' measurements perturb
the state of quantum systems. We show that the absence of energy exchange
during the measurement is not a sufficient criterion to preserve that state, as
the quantum system is subject to measurement dependent decoherence. While it is
possible in general to design interaction-free measurement schemes that do
preserve that state, the requirement of quantum coherence preservation rapidly
leads to a very low efficiency. Our results, which have a simple interpretation
in terms of ``which-way'' arguments, open up the way to novel quantum
non-demolition techniques.Comment: 4 pages incl. 2 PostScript figures (.eps), LaTeX using RevTeX,
submitted to Phys. Rev. A (Rapid Comm.
Extracting atoms on demand with lasers
We propose a scheme that allows us to coherently extract cold atoms from a reservoir in a deterministic way. The transfer is achieved by means of radiation pulses coupling two atomic states which are object to different trapping conditions. A particular realization is proposed, where one state has zero magnetic moment and is confined by a dipole trap, whereas the other state with nonvanishing magnetic moment is confined by a steep microtrap potential. We show that in this setup a predetermined number of atoms can be transferred from a reservoir, a Bose-Einstein condensate, into the collective quantum state of the steep trap with high efficiency in the parameter regime of present experiments
Isolation and linkage analysis of expressed disease-resistance gene analogues of sugar beet (Beta vulgaris L.)
Hunger S, Di Gaspero G, Mohring S, et al. Isolation and linkage analysis of expressed disease-resistance gene analogues of sugar beet (Beta vulgaris L.). Genome. 2003;46(1):70-82.Sequence conservation among resistance genes (R genes) was exploited to identify 47 R gene analogues (RGAs) from sugar beet (Beta vulgaris L.). Using degenerate primers, 11 RGAs were amplified from genomic DNA and 7 from leaf or beet cDNA. Twenty-nine were selected from an EST sequencing program. Twenty-one RGAs contained structures similar to the nucleotide binding site (NBS)--leucine rich repeat (LRR) domain, a motif commonly found in several R genes. Among the remaining RGAs, 19 revealed similarity to the serine (threonine) protein kinase domain of R genes, 4 showed features related to the LRR region of the rice disease resistance gene Xa21, 1 RGA resembled the sugar beet nematode resistance gene Hs1pro-1, and 2 had homologies to other gene products associated with disease resistance. For 20 EST-derived RGAs, transcript levels were compared in leaf and root tissue revealing organ-specific transcription in 7 cases. Thirty-three RGAs were spread over all nine sugar beet chromosomes, except for a cluster of nine closely linked RGAs on chromosome 7. The analysis of linkage between RGAs and loci for rhizomania and Cercospora resistance identified alleles associated with resistance in both cases
High-throughput identification of genetic markers using representational oligonucleotide microarray analysis
Lange C, Mittermayr L, Dohm JC, Holtgräwe D, Weisshaar B, Himmelbauer H. High-throughput identification of genetic markers using representational oligonucleotide microarray analysis. Theoretical and Applied Genetics. 2010;121(3):549-565