219 research outputs found
Textures of Spin-Orbit Coupled F=2 Spinor Bose Einstein Condensates
We study the textures of F=2 spinor Bose-Einstein condensates (BECs) with
spin-orbit coupling (SOC) induced by a synthetic non-Abelian gauge field. On
the basis of the analysis of the SOC energy and the numerical calculation of
the Gross-Pitaevskii equation, we demonstrate that the textures originate from
the helical modulation of the order parameter (OP) due to the SOC. In
particular, the cyclic OP consists of two-dimensional lattice textures, such as
the hexagonal lattice and the 1/3-vortex lattice, commonly understandable as
the two-dimensional network of the helical modulations.Comment: 5 pages, 5 figure
Dissociation and Nucleation of Tetra-n-butyl Ammonium Bromide Semi-Clathrate Hydrates at High Pressures
The equilibrium pressure-temperature relations of the tetra-n-butyl ammonium bromide (TBAB) semiclathrate hydrate were measured at pressures of up to 80 MPa by high-pressure differential scanning calorimetry. As a pressurizing medium, tetrafluoromethane (CF4), which cannot occupy any hydrate cages in the TBAB semiclathrate hydrate at the present experimental pressures, was used. The dissociation temperature of tetragonal TBAB semiclathrate hydrate (TBAB·26H2O) increases with the increase in pressure, whereas the dissociation enthalpy is (192 ± 3) J·g-1 and almost constant at pressures of up to 80 MPa. The temperature difference between formation and dissociation at the same pressure, that is, the maximum allowable degree of supercooling, is (17.7 ± 0.7) K and independent of the pressure.Takeshi Sugahara and Hironobu Machida. Dissociation and Nucleation of Tetra-n-butyl Ammonium Bromide Semi-Clathrate Hydrates at High Pressures. Journal of Chemical & Engineering Data, 62 (9), 2721–2725, September 14, © 2017 American Chemical Society. https://doi.org/10.1021/acs.jced.7b0011
Coreless and singular vortex lattices in rotating spinor Bose-Einstein condensates
We theoretically investigate vortex-lattice phases of rotating spinor
Bose-Einstein condensates (BEC) with the ferromagnetic spin-interaction by
numerically solving the Gross-Pitaevskii equation. The spinor BEC under slow
rotation can sustain a rich variety of exotic vortices due to the
multi-component order parameters, such as the Mermin-Ho and Anderson-Toulouse
coreless vortices (the 2-dimensional skyrmion and meron) and the
non-axisymmetric vortices with the sifting vortex cores. Here, we present the
spin texture of various vortex-lattice states at higher rotation rates and in
the presence of the external magnetic field. In addition, the vortex phase
diagram is constructed in the plane by the total magnetization and the
external rotation frequency by comparing the free energies of possible
vortices. It is shown that the vortex phase diagram in a - plane may
be divided into two categories; (i) the coreless vortex lattice formed by the
several types of Mermin-Ho vortices and (ii) the vortex lattice filling in the
cores with the pure polar (antiferromagnetic) state. In particular, it is found
that the type-(ii) state forms the composite lattices of coreless and
polar-core vortices. The difference between the type-(i) and type-(ii) results
from the existence of the singularity of the spin textures, which may be
experimentally confirmed by the spin imaging within polarized light recently
proposed by Carusotto and Mueller. We also discussed on the stability of
triangular and square lattice states for rapidly rotating condensates.Comment: to be published in Phys. Rev.
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