arXiv subjects

Natalia G. Berloff

Publications and source records attributed to Natalia G. Berloff.

76 records · Page 5Linked to original sources

arXiv2003

Pade approximations of solitary wave solutions of the Gross-Pitaevskii equation

Pade approximants are used to find approximate vortex solutions of any winding number in the context of Gross-Pitaevskii equation for a uniform condensate and condensates with axisymmetric trapping potentials. Rational function and generalised rational function approximations of axisymmetric solitary waves of the Gross-Pitaevskii equation are obtained in two and three dimensions. These approximations are used to establish a new mechanism of vortex nucleation as a result of solitary wave interactions.

cond-mat.soft↗

arXiv2001

Scenario of strongly non-equilibrium Bose-Einstein condensation

Large scale numerical simulations of the Gross-Pitaevskii equation are used to elucidate the self-evolution of a Bose gas from a strongly non-equilibrium initial state. The stages of the process confirm and refine the theoretical scenario of Bose-Einstein condensation developed by Svistunov, Kagan, and Shlyapnikov [1-3]: the system evolves from the regime of weak turbulence to superfluid turbulence, via states of strong turbulence in the long-wavelength region of energy space.

cond-mat.soft↗

arXiv2001

Evolution of rarefaction pulses into vortex rings

The two-dimensional solitary waves of the Gross-Pitaevskii equation in the Kadomtsev-Petviashvili limit are unstable with respect to three-dimensional perturbations. We elucidate the stages in the evolution of such solutions subject to perturbations perpendicular to the direction of motion. Depending on the energy (momentum) and the wavelength of the perturbation different types of three-dimensional solutions emerge. In particular, we present new periodic solutions having very small energy and momentum per period. These solutions also become unstable and this secondary instability leads to vortex ring nucleation.

cond-mat.soft↗

arXiv2001

Motion in a Bose condensate: IX. Crow instability of antiparallel vortex pairs

The Gross-Pitaevskii (GP) equation admits a two-dimensional solitary wave solution representing two mutually self-propelled, anti-parallel straight line vortices. The complete sequence of such solitary wave solutions has been computed by Jones and Roberts (J. Phys. A, 15, 2599, 1982). These solutions are unstable with respect to three-dimensional perturbations (the Crow instability). The most unstable mode has a wavelength along the direction of the vortices of the same order as their separation. The growth rate associated with this mode is evaluated here, and it is found to increase very rapidly with decreasing separation. It is shown, through numerical integrations of the GP equation that, as the perturbations grow to finite amplitude, the lines reconnect to produce a sequence of almost circular vortex rings.

cond-mat.soft↗