http://arxiv.org/abs/2305.01675
We provide an algorithm for evolving general spin-$s$ Gross-Pitaevskii / non-linear Schr\”odinger systems carrying a variety of interactions, where the $2s+1$ components of the `spinor’ field represent the different spin-multiplicity states. We consider many nonrelativistic interactions up to quartic order in the Schr\”odinger field (both short and long-range, and spin-dependent and spin-independent interactions), including explicit spin-orbit couplings. The algorithm allows for spatially varying external and/or self-generated vector potentials that couple to the spin density of the field. Our work can be used for scenarios ranging from laboratory systems such as spinor Bose-Einstein condensates (BECs), to cosmological/astrophysical systems such as self-interacting bosonic dark matter. As examples, we provide results for two different setups of spin-$1$ BECs that employ a varying magnetic field and spin-orbit coupling, respectively, and also collisions of spin-$1$ solitons in dark matter. Our symplectic algorithm is second-order accurate in time, and is extensible to the known higher-order accurate methods.
M. Jain, M. Amin and H. Pu
Thu, 4 May 23
23/60
Comments: 13 pages, 3 figures, 2 appendices