Control of Light-Atom Solitons and Atomic Transport by Optical Vortex Beams Propagating through a Bose-Einstein Condensate

We model propagation of far-red-detuned optical vortex beams through a Bose-Einstein condensate using nonlinear Schrödinger and Gross-Pitaevskii equations. We show the formation of coupled light-atomic solitons that rotate azimuthally before moving off tangentially, carrying angular momentum. The number, and velocity, of solitons, depends on the orbital angular momentum of the optical field. Using a Bessel-Gauss beam increases radial confinement so that solitons can rotate with fixed azimuthal velocity. Our model provides a highly controllable method of channeling a BEC and atomic transport.

Figure 1

(a) An input laser beam is incident on an SLM, which can add OAM, before propagating through a cigar-shaped BEC medium moving at velocity $v_a$, suspended by additional horizontal and vertical trapping fields, to a detector. (b) Transverse cross sections of Thomas-Fermi BEC amplitude with $w_{\psi }=50.0\mu \mathrm{m}$ (i), and Laguerre-Gauss optical field amplitude (ii) and phase (iii) with $m=1$ and $w_F=10\mu \mathrm{m}$.

Figure 2

Coincident pattern formation in both BEC and optical fields for Gaussian input profiles as in Ref. [16]. Transverse scales as in Fig. 1. Parameters: ${\beta }_{\mathrm{col}}=3.5$, $L_3=0.00022$, $s=-1$, $w_F=50\mu \mathrm{m}$, $A_F=6$, $w_{\psi }=50\mu \mathrm{m}$, $A_{\psi }=6$.

Figure 3

Panels (a)–(d) and (i)–(l): transverse amplitude cross section of BEC and optical fields, respectively, for $m=-1$, 1, 2, 3 (top to bottom) at $\zeta =z_R$. Panels (e)–(h) and (m)–(p): superimposed images of transverse BEC and optical amplitude distributions, respectively, $\zeta =0.5\to 4z_R$. Parameters as in Fig. 2, with $w_F=10\mu \mathrm{m}$, $A_F=9.5$, $A_{\psi }=9.5$.

Figure 4

Three-dimensional BEC distribution for the $m=2$ case of Fig. 3, $\zeta =0\to 2.5z_R$. Transverse scales as in Fig. 1. Parameters as in Fig. 3.