Stability of the quantized circulation of an attractive Bose-Einstein condensate in a rotating torus

Tapio Simula, Suvi Mirjami Virtanen, M.M. Salomaa

Rina Kanamoto, Hiroki Saito, Masahito Ueda

We investigate rotational properties of a system of attractive bosons confined in a one-dimensional torus. Two kinds of ground states, uniform-density and bright soliton, are obtained analytically as functions of the strength of interaction and of the rotational frequency of the torus. The quantization of circulation appears in the uniform-density state, but disappears upon formation of the soliton. By comparing the results of exact diagonalization with those predicted by the Bogoliubov theory, we show that the Bogoliubov theory is valid at absolute zero over a wide range of parameters. At finite temperatures we employ the exact diagonalization method to examine how thermal fluctuations smear the plateaus of the quantized circulation. Finally, by rotating the system with an axisymmetry-breaking potential, we clarify the process by which the quantized circulation becomes thermodynamically stabilized.

Jack Arbunich, Irina Nenciu, Christof Sparber

Bijnen RMW van, DHJ O'Dell, Nicholas G. Parker +1 more

Masahito Ueda, Anthony J. Leggett

The ground state of a rotating Bose-Einstein condensate with attractive interaction in a quasi-one-dimensional torus is studied in terms of the ratio $\ensuremath{\gamma}$ of the mean-field interaction energy per particle to the single-particle energy-level spacing. The plateaus of quantized circulation are found to appear if and only if $\ensuremath{\gamma}<1$ with the lengths of the plateaus reduced due to hybridization of the condensate over different angular-momentum states.

Alexander L. Fetter, Anatoly A. Svidzinsky