Controlled creation of spin domains in spin-1 Bose-Einstein condensates by phase separation

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.

Figure 1

(a) Ground state of a sodium condensate with fixed magnetization $M=0.4$, number of atoms $N=8.4\times {10}^3$, trap frequencies ${\omega }_{\rho }=2\pi \times 1000$Hz and ${\omega }_z=2\pi \times 2.5$Hz, and the magnetic field strength $B=120$mG. The $n_{+}$, $n_0$, and $n$ components are depicted by dash-dotted, dashed, and dotted lines, respectively, and the solid lines show the total density. (b) The result of a slow introduction of a Gaussian-shaped barrier with $A=3.3\times {10}^{-30}$J and $w=90\mu$m during the time $t=5$s.

Figure 2

(a) Ground state of the double-well potential with parameters as in Fig. 1. (b) For comparison, we show the ground state in the absence of the Gaussian barrier. (c) Metastable spin-domain structure obtained starting from (a), after the removal of the Gaussian barrier within $t=5$s. (d)–(f) Same as (a)–(c), but for a weaker magnetic field $B=45$mG and magnetization $M=0.8$.

Figure 3

(a) Ground state in a periodic potential with $d=140\mu$m and $A=3.3\times {10}^{-30}$J. (b) The resulting domain structure after switching the potential off during $t=5$s.

Figure 4

Same as in Fig. 2c, but (a) for ${\omega }_z=2\pi \times 10$Hz and $N=2100$ and (b) for ${\omega }_z=2\pi \times 20$Hz and $N=1050$.

Figure 5

Ground state of the double-well potential for parameters as in Fig. 2a but with $w=9.4\mu$m.