Search

The main obstacle in the experimental realization of the Einstein-de Haas effect in a Bose-Einstein condensate is the need for very precise control of the extremely small (of the order of tens of μG) external magnetic field. In this paper, we numerically study the response of a rubidium condensate to a magnetic field that is linearly dependent on time. We find a significant transfer of atoms from the initial maximally polarized state to the next Zeeman component at magnetic fields of the order of tens of milligauss. We propose an experiment in which such a time-dependent magnetic-field-based scheme could enable the observation of the Einstein-de Haas effect in a rubidium atom condensate. [ABSTRACT FROM AUTHOR]

We present a method for investigating nonequilibrium dynamics of an ultracold system that is initially at thermal equilibrium. Our procedure is based on the classical fields approximation and appropriately prepared initial state for antiferromagnetic condensate with fixed magnetization. As an application of the method, we investigate the influence of thermal fluctuations on the quantum phase transition from an antiferromagnetic to phase separated ground state in a spin-1 Bose-Einstein condensate of ultracold atoms. We find that at temperatures significantly lower than the critical condensation temperature Tc the scaling law for the number of created spin defects remains intact. [ABSTRACT FROM AUTHOR]

A method of controlled creation of spin domains in spin-1 antiferromagnetic Bose-Einstein condensates is demonstrated. The method exploits the phenomenon of phase separation of spin components in an external potential. By using an appropriate time-dependent potential, a composition of spin domains can be created, as demonstrated in the particular cases of a double well and a periodic potential. In contrast to other methods, which rely on spatially inhomogeneous magnetic fields, here the domain structure is completely determined by the optical fields, which makes the method versatile and reconfigurable. It allows for creation of domains of various sizes, with the spatial resolution limited by the spin healing length only. [ABSTRACT FROM AUTHOR]

We study the effect of an external harmonic trapping potential on an outcome of the nonadiabatic quantum phase transition from an antiferromagnetic to a phase-separated state in a spin-1 atomic condensate. Previously, we demonstrated that the dynamics of an untrapped system exhibits double universality with two different scaling laws appearing due to the conservation of magnetization. We show that in the presence of a trap, double universality persists. However, the corresponding scaling exponents are strongly modified by the transfer of local magnetization across the system. The values of these exponents cannot be explained by the effect of causality alone, as in the spinless case. We derive the appropriate scaling laws based on a slow diffusive-drift relaxation process in the local density approximation. [ABSTRACT FROM AUTHOR]