Search results for "quantum gas"
showing 10 items of 654 documents
Quantum gases in optical lattices
2004
IMAGINE having an artificial substance in which you can control almost all aspects of the underlying periodic structure and the interactions between the atoms that make up this dream material. Such a substance would allow us to explore a whole range of fundamental phenomena that are extremely difficult – or impossible – to study in real materials. It may sound too good to be true, but over the last two years physicists have come extremely close to achieving this goal.
Optimal geometry for efficient loading of an optical dipole trap
2009
One important factor which determines efficiency of loading cold atoms into an optical dipole trap from a magneto-optical trap is the distance between the trap centers. By studying this efficiency for various optical trap depths (2--110 mK) we find that for optimum dipole trap loading, longitudinal displacements up to 15 mm are necessary. An explanation for this observation is presented and compared with other work and a simple analytical formula is derived for the optimum distance between the trap centers.
In-trap conversion electron spectroscopy
2002
The Penning trap REXTRAP at ISOLDE was used to test the feasibility of in-trap conversion electron spectroscopy. The results of simulations, experiments with solid conversion electron sources as well as first on-line and tests with trapped radioactive ions are presented. In addition to obtaining high-resolution spectroscopic data, the detection of conversion electrons was found to be a useful tool for the diagnostics of the trap operation. The tests proved the feasibility of in-trap spectroscopy but also revealed some potential problems to be addressed in the future.
Exploring Interacting Topological Insulators with Ultracold Atoms: The Synthetic Creutz-Hubbard Model
2016
25 pags., 13 figs. -- Open Access funded by Creative Commons Atribution Licence 4.0
Pseudo-Bosons from Landau Levels
2010
We construct examples of pseudo-bosons in two dimensions arising from the Hamiltonian for the Landau levels. We also prove a no-go result showing that non-linear combinations of bosonic creation and annihilation operators cannot give rise to pseudo-bosons.
From pseudo-bosons to pseudo-Hermiticity via multiple generalized Bogoliubov transformations
2016
We consider the special type of pseudo-bosonic systems that can be mapped to standard bosons by means of generalized Bogoliubov transformation and demonstrate that a pseudo-Hermitian systems can be obtained from them by means of a second subsequent Bogoliubov transformation. We employ these operators in a simple model and study three different types of scenarios for the constraints on the model parameters giving rise to a Hermitian system, a pseudo-Hermitian system in which the second the Bogoliubov transformations is equivalent to the associated Dyson map and one in which we obtain D-quasi bases.
"Table 4" of "Search for dark matter in events with a hadronically decaying W or Z boson and missing transverse momentum in pp collisions at sqrt(s)=…
2014
Observed limits on the effective theory mass scale M* as a function of the dark matter mass M(chi) at 90% confidence-level from combined mono-W-boson and mono-Z-boson signals for various operators.
Controlling the interactions of a few cold Rb Rydberg atoms by radiofrequency-assisted F��rster resonances
2014
Long-range interactions between cold Rydberg atoms, which are used in many important applications, can be enhanced using F��rster resonances between collective many-body states controlled by an external electric field. Here we report on the first experimental observation of highly-resolved radio-frequency-assisted F��rster resonances in a few cold Rb Rydberg atoms. We also observed radio-frequency-induced F��rster resonances which cannot be tuned by a dc electric field. They imply an efficient transition from van der Waals to resonant dipole-dipole interaction due to Floquet sidebands of Rydberg levels appearing in the rf-field. This method can be applied to enhance the interactions of almo…
Strong interaction regime of the nonlinear Landau-Zener problem for photo- and magneto-association of cold atoms
2009
We discuss the strong interaction regime of the nonlinear Landau-Zener problem coming up at coherent photo- and magneto-association of ultracold atoms. We apply a variational approach to an exact third-order nonlinear differential equation for the molecular state probability and construct an accurate approximation describing the whole time dynamics of the coupled atom-molecular system. The resultant solution improves the accuracy of the previous approximation by A. Ishkhanyan et al. [J. Phys. A 39, 14887 (2006)]. The obtained results reveal a remarkable observation that in the strong coupling limit the resonance crossing is mostly governed by the nonlinearity while the coherent atom-molecul…
Determination of the Transverse Momentum of W Bosons in Hadronic Collisions via Forward Folding Techniques
2015
The measurement of the transverse momentum of W bosons in hadron collisions provides not only an important test of QCD calculations, but also is an important input for the precision measurement of the W boson mass. While the measurement of the Z boson transverse momentum is experimentally well under control, the available unfolding techniques for the W boson final states lead generically to relatively large uncertainties. In this paper, we present a new methodology to estimate the W boson transverse momentum spectrum, significantly improving the systematic uncertainties of current approaches.