Entangling Two Bose-Einstein Condensates by Stimulated Bragg Scattering

We propose an experiment for entangling two spatially separated Bose-Einstein condensates by Bragg scattering of light. When Bragg scattering in two condensates is stimulated by a common probe, the resulting quasiparticles in the two condensates get entangled due to quantum communication between the condensates via probe beam. The entanglement is shown to be significant and occurs in both number and quadrature phase variables. We present two methods of detecting the generated entanglement.Comment: 4 pages, Revte

On the single mode approximation in spinor-1 atomic condensate

We investigate the validity conditions of the single mode approximation (SMA) in spinor-1 atomic condensate when effects due to residual magnetic fields are negligible. For atomic interactions of the ferromagnetic type, the SMA is shown to be exact, with a mode function different from what is commonly used. However, the quantitative deviation is small under current experimental conditions (for $^{87}$Rb atoms). For anti-ferromagnetic interactions, we find that the SMA becomes invalid in general. The differences among the mean field mode functions for the three spin components are shown to depend strongly on the system magnetization. Our results can be important for studies of beyond mean field quantum correlations, such as fragmentation, spin squeezing, and multi-partite entanglement.Comment: Revised, newly found analytic proof adde

The dynamics of quantum phases in a spinor condensate

We discuss the quantum phases and their diffusion dynamics in a spinor-1 atomic Bose-Einstein condensate. For ferromagnetic interactions, we obtain the exact ground state distribution of the phases associated with the total atom number ($N$), the total magnetization (${\cal M}$), and the alignment (or hypercharge) ($Y$) of the system. The mean field ground state is stable against fluctuations of atom numbers in each of the spin components, and the phases associated with the order parameter for each spin components diffuse while dynamically recover the two broken continuous symmetries [U(1) and SO(2)] when $N$ and ${\cal M}$ are conserved as in current experiments. We discuss the implications to the quantum dynamics due to an external (homogeneous) magnetic field. We also comment on the case of a spinor-1 condensate with anti-ferromagnetic interactions.Comment: 5 figures, an extended version of cond-mat/030117