Coherence Properties of a Bose-Einstein Condensate in an Optical Superlattice

We study the effect of a one dimensional optical superlattice on the superfluid fraction, number squeezing, dynamic structure factor and the quasi-momentum distribution of the Mott-insulator. We show that due to the secondary lattice,there is a decrease in the superfluid fraction and the number fluctuation. The dynamic structure factor which can be measured by Bragg spectroscopy is also suppressed due to the addition of the secondary lattice. The visibility of the interference pattern (the quasi-momentum distribution)of the Mott-insulator is found to decrease due to the presence of the secondary lattice. Our results have important implications in atom interferometry and quantum computation in optical lattices.Comment: 12 pages, 5 figure

Influence of Virtual Photon Process on the Generation of Squeezed Light from Atoms in an Optical Cavity

We show that a collection of two-level atoms in an optical cavity beyond the rotating wave approximation and in the dispersive and strong-coupling regime constitutes a nonlinear medium and is capable of generating squeezed state of light. It is found that squeezing produced in the strong-coupling regime is significantly higher compared to that produced in the dispersive limit. On the other hand, we also show that it could be possible to observe the Dicke superradiant quantum phase transition in the dispersive regime where the vector potential term is negligible. Such a system can be an essential component of a larger quantum-communication system.Comment: 6 pages, 3 figures, Comments Welcom

The Excited Scalars of the Universal Extra Dimension Model

In the minimal Universal Extra Dimension (mUED) model, there are four physical scalar particles at the n=1 level, two charged and two neutral. Due to the almost degenerate nature of the spectrum, the detection of these scalars is a major challenge, perhaps the greatest experimental challenge if UED-type new physics is observed at the Large Hadron Collider (LHC). We explore the possibility of detecting these particles at the International Linear Collider (ILC), and emphasise the need of having an excellent soft tau detection efficiency.Comment: 12 pages, 9 figures: minor changes from v1, version to be publishe