We propose a scheme for the generation of arbitrary coherent superpositions of vortex states in Bose-Einstein condensates (BEC) using the orbital-angular-momentum states of light. We devise a scheme to generate coherent superpositions of two such counterrotating states of light using well-known experimental techniques. We show that a specially designed Raman scheme allows for transfer of the op...

1. Haldor Topsøe A/S, Nymøllevej 55, DK-2800 Kgs. Lyngby, Denmark. 2. Nano-Science Center, Niels Bohr Institute, Universitetsparken 5, DK-2100, Copenhagen, Denmark. 3. SuperSTEM Laboratory, STFC Daresbury, Keckwick Lane, Daresbury WA4 4AD, United Kingdom 4. Lawrence Berkeley National Laboratory, National Center for Electron Microscopy and Joint Center for Artificial Photosynthesis, Berkeley CA ...

We introduce the notion of a special monopole class on a four-manifold. This is used to prove restrictions on the smooth structures of Einstein manifolds. As an application we prove that there are Einstein four-manifolds which are simply connected, spin, and satisfy the strict Hitchin–Thorpe inequality, and which are homeomorphic to manifolds without Einstein metrics.

Metastable triplet helium is an interesting atom, next to the alkalis and atomic hydrogen, to pursue Bose–Einstein condensation. In this paper an overview of the relevant physics of triplet helium and experimental progress in Amsterdam towards reaching Bose– Einstein condensation is described.  2001 Académie des sciences/Éditions scientifiques et médicales Elsevier SAS cold atoms / metastable ...

A compact quasi-regular Sasakian manifold M is foliated by onedimensional leaves and the transverse space of this characteristic foliation is necessarily a compact Kähler orbifold Z. In the case when the transverse space Z is also Einstein the corresponding Sasakian manifold M is said to be Sasakian η-Einstein. In this article we study η-Einstein geometry as a class of distinguished Riemannian ...

Using Gross-Pitaevskii equation, we study the time reversibility of Bose-Einstein condensates (BEC) in kicked optical lattices, showing that in the regime of quantum chaos, the dynamics can be inverted from explosion to collapse. The accuracy of time reversal decreases with the increase of atom interactions in BEC, until it is completely lost. Surprisingly, quantum chaos helps to restore time r...

We present a representation for the long–range part of the general 0νββ decay rate allowed by lorentz–invariance. Combined with the short range part this general parametriza-tion in terms of effective B − L violating couplings will provide the 0νββ limits on arbitrary lepton number violating theories. " One must be prepared for surprises, not anywhere but specifically with the beta decay " (Nie...

In this article, we consider the almost Hermitian structure on TM induced by a pair of a metric and an affine connection on M . We find the conditions under which TM admits almost Kähler structures, Kähler structures and Einstein metrics, respectively. Moreover, we give two examples of Kähler-Einstein structures on TM . 2000 Mathematics Subject Classification: 53C55, 53C15, 53C25.

We consider the effect of inhomogeneities on the expansion of the Einstein-de Sitter universe. We find that the backreaction of linear scalar metric perturbations results in apparent dark energy with a mixture of equations of state between 0 and –4/3. We discuss the possibility that backreaction could account for present-day acceleration.