"Stable two-dimensional composite solitons in spin-orbit-coupled self-attractive Bose-Einstein condensates in free space" Boris A. Malomed

"Stable two-dimensional composite solitons in spin-orbit-coupled self-attractive Bose-Einstein condensates in free space"

Prof. Boris Malomed
Professor, Tel Aviv University, Israel

• Monday, 6 October
• 10:30-11:30
• Meeting Room D014, Lab1

Abstract:
It is commonly known that two-dimensional mean-field models of optical and matter waves with cubic self-attraction cannot produce stable solitons in free space because of the occurrence of collapse in the same setting. By means of numerical analysis and variational approximation, we demonstrate that the two-component model of the Bose-Einstein condensate with the Rashba spin-orbit coupling and cubic attractive interactions gives rise to STABLE solitary-vortex complexes of two types in the FREE SPACE: semivortices (SVs, with a vortex in one component and a fundamental soliton in the other), and mixed modes (MMs, with topological charges 0 and ±1 mixed in both components). The SVs and MMs realize the ground state of the system, provided that the self-attraction in the two components is, respectively, stronger or weaker than the cross attraction between them. The SVs and MMs which are not the ground states are subject to a drift instability. The modes of both types degenerate into unstable Townes solitons when their norms attain the respective critical values, while there is no lower existence threshold for the stable modes. Moving free-space stable solitons are also found in the present non-Galilean-invariant system, up to a critical velocity. Collisions between two moving solitons lead to their merger into a single one.

The work has been published in Phys. Rev. E 89, 032920 (2014).

We look forward to seeing many of you at this seminar.

Quantum Systems Unit