Selective coherent spin transportation in a spin-orbit-coupled bosonic junction

We propose a theoretical scheme for realizing selective coherent spin transportation in a spin-orbit-coupled bosonic gas trapped in a symmetric double well by fast modulation of the energy-level unbalance between the two wells. The modulation can be tuned in such a way that an arbitrarily, a priori prescribed spin type (single spin or a spin pair with opposite spins) and the number of these spin bosons with or without spin flipping are allowed to tunnel. Furthermore, prescribed superexchange of spin bosons (where only pure spin exchange is allowed between the two wells and the atom number in each well is not changed) is also presented. The resonance conditions of realizing this selective coherent spin transportation are obtained analytically and confirmed numerically. This engineering provides a possible means for spin control and accurate counting or efficient filtering of the number of spins.

Figure 1

Evolution of the occupation probabilities $D_l^k\left(t\right)$ for the selective coherent transportation of $l$ spin-up bosons without spin flipping. The first column shows a schematic diagram showing spin transportation. From the first panel to the fourth panel, $\Gamma =0,11.09,12.35,9.76$, respectively.

Figure 2

(a) The first Bessel functions ${\mathrm{J}}_n$ of order $n=19,9,7,5,3$. (b) Behavior of quasi-energy spectrum for the selective coherent spin transportation for single spin-up bosons.

Figure 3

Same as in Fig. 1 but with spin flipping (spin-up bosons that tunneled to the left well are flipped to spin down). From the first panel to the fourth panel, $\Gamma =0,11.06,10.17,9.94$, respectively.

Figure 4

Same as in Fig. 1 but for transportation of $l$ spin pairs without spin flipping (the first panel with $\Gamma =5.14$ and the second panel with $\Gamma =5.52$) and with spin flipping (the third panel with $\Gamma =5.14$ and the fourth panel with $\Gamma =5.52$).

Figure 5

Same as in Fig. 1 but for superexchange of spin bosons without spin flipping (the first panel with $\Gamma =5.14$ and the second panel with $\Gamma =5.52$) and only single-spin-up transportation without spin flipping (the third panel with $\Gamma =11.09$ and the fourth panel with $\Gamma =12.35$).