We present a complete recipe to extract the density–density correlations and the static structure factor of a two-dimensional (2D) atomic quantum gas from in situ imaging. Using images of non-interacting thermal gases, we characterize and remove the systematic contributions of imaging aberrations to the measured density–density correlations of atomic samples. We determine the static structure f...

Nonlinear dynamics of a trapped Bose-Einstein condensate, subject to the action of a resonant external field, is studied. This field produces a spatio-temporal modulation of the trapping potential with the frequency close to the transition frequency between the ground state and a higher energy level. The evolution equations of fractional populations display a kind of critical phenomena at a cri...

According to a formula that was put forward many decades ago the ground state energy per particle of an interacting, dilute Bose gas at density is 2~ 2 a=m to leading order in a 3 1, where a is the scattering length of the interaction potential and m the particle mass. This result, which is important for the theoretical description of current experiments on Bose-Einstein condensation, has recen...

A review is given of recent theoretical work on the superfluid dynamics of trapped Bose gases at finite temperatures, where there is a significant fraction of non-condensate atoms. One can now reach large enough densities and collision cross-sections needed to probe the collective modes in the collisiondominated hydrodynamic region where the gas exhibits characteristic superfluid behavior invol...

We extend the Projected Gross Pitaevskii equation formalism of Davis et al. [Phys. Rev. Lett. 87, 160402 (2001)] to the experimentally relevant case of harmonic potentials. We outline a robust and accurate numerical scheme that can efficiently simulate this system. We apply this method to investigate the equilibrium properties of a harmonically trapped three-dimensional Bose gas at finite tempe...

This paper discusses our recent work on developing the matter wave analogs to the Hanbury Brown Twiss experiment. We discuss experiments using cold atoms, both bosons and fermions, both coherent and incoherent. Simple concepts from classical and quantum optics suffice to understand most of the results, but the ideas can also be traced back to the work of Einstein on the thermodynamics of Bose g...

We here develop a theory on optical absorption in a dilute Bose gas at low temperatures. This theory is motivated by the Bogoliubov theory of elementary excitations for this system, and takes into account explicitly the modification of the nature and dispersion of elementary excitations due to Bose-Einstein condensation. Our results show important differences from existing theories. PACS number...

We describe the quantum state of a Bose-Einstein condensate at zero temperature. By evaluating the Q-function we show that the ground state of Bose-Einstein condensate under the Hartree approximation is squeezed. We find that multimode Schrödinger cat states are generated as the condensate evolves in a ballistic expansion.

A rotated and harmonically trapped Bose gas with attractive interactions is expected to either remain stationary or escape from the trap. Here we report that, on the contrary, in an anharmonic trapping potential the Bose gas with attractive interactions responds to external rotation very differently, namely, through center-of-mass motion or by formation of vortices.

We study the collisional and collapse dynamics of a twin Bose{Einstein con-densate with an attractive interatomic interaction. We show that the collision between two Bose{Einstein components with densities higher than the critical density for instability can rst lead to a collapse due to the attractive interatomic interaction followed by a cessation of collapse due to the mutual nonlinear inter...