arXiv subjects

R A Smith

Publications and source records attributed to R A Smith.

2 recordsLinked to original sources

arXiv2000

Exact Eigenstates for Repulsive Bosons in Two Dimensions

We consider a model of $N$ two-dimensional bosons in a harmonic potential with weak repulsive delta-function interactions. We show analytically that, for angular momentum $L\le N$, the elementary symmetric polynomials of particle coordinates measured from the center of mass are exact eigenstates with energy $N(N-L/2-1)$. Extensive numerical analysis confirms that these are actually the ground states, but we are currently unable to prove this analytically. The special case $L=N$ can be thought of as the generalisation of the usual superfluid one-vortex state to Bose-Einstein condensates in a trap.

cond-mat↗

arXiv1997

Do attractive bosons condense?

Motivated by experiments on bose atoms in traps which have attractive interactions (e.g. ^7Li), we consider two models which may be solved exactly. We construct the ground states subject to the constraint that the system is rotating with angular momentum proportional to the number of atoms. In a conventional system this would lead to quantised vortices; here, for attractive interactions, we find that the angular momentum is absorbed by the centre of mass motion. Moreover, the state is uncondensed and is an example of a `fragmented' condensate discussed by Nozières and Saint James. The same models with repulsive interactions are fully condensed in the thermodynamic limit.

cond-mat.stat-mech↗