arXiv subjects

Keith Burnett

Publications and source records attributed to Keith Burnett.

22 records · Page 2Linked to original sources

arXiv2003

The nature of Feshbach molecules in Bose-Einstein condensates

We discuss the long range nature of the molecules produced in recent experiments on molecular Bose-Einstein condensation. The properties of these molecules depend on the full two-body Hamiltonian and not just on the states of the system in the absence of interchannel couplings. The very long range nature of the state is crucial to the efficiency of production in the experiments. Our many-body treatment of the gas accounts for the full binary physics and describes properly how these molecular condensates can be directly probed.

cond-mat↗

arXiv2003

Bogoliubov approach to superfluidity of atoms in an optical lattice

We use the Bogoliubov theory of atoms in an optical lattice to study the approach to the Mott-insulator transition. We derive an explicit expression for the superfluid density based on the rigidity of the system under phase variations. This enables us to explore the connection between the quantum depletion of the condensate and the quasi-momentum distribution on the one hand and the superfluid fraction on the other. The approach to the insulator phase may be characterized through the filling of the band by quantum depletion, which should be directly observable via the matter wave interference patterns. We complement these findings by self-consistent Hartree-Fock-Bogoliubov-Popov calculations for one-dimensional lattices including the effects of a parabolic trapping potential.

cond-mat.soft↗

arXiv2002

Microscopic theory of atom-molecule oscillations in a Bose-Einstein condensate

In a recent experiment at JILA [E.A. Donley et al., Nature (London) 417, 529 (2002)] an initially pure condensate of Rb-85 atoms was exposed to a specially designed time dependent magnetic field pulse in the vicinity of a Feshbach resonance. The production of new components of the gas as well as their oscillatory behavior have been reported. We apply a microscopic theory of the gas to identify these components and determine their physical properties. Our time dependent studies allow us to explain the observed dynamic evolution of all fractions, and to identify the physical relevance of the pulse shape. Based on ab initio predictions, our theory strongly supports the view that the experiments have produced a molecular condensate.

cond-mat↗

arXiv2001

A microscopic quantum dynamics approach to the dilute condensed Bose gas

We derive quantum evolution equations for the dynamics of dilute condensed Bose gases. The approach contains, at different orders of approximation, for cases close to equilibrium, the Gross Pitaevskii equation and the first order Hartree Fock Bogoliubov theory. The proposed approach is also suited for the description of the dynamics of condensed gases which are far away from equilibrium. As an example the scattering of two Bose condensates is discussed.

cond-mat↗