One- and two-dimensional optical lattices on a chip for quantum computing

We propose a way to make arrays of optical frequency dipole-force microtraps for cold atoms above a dielectric substrate. Traps are nodes in the evanescent wave fields above an optical waveguide resulting from interference of different waveguide modes. The traps have features sought in developing neutral atom based architectures for quantum computing: $\sim 1\mathrm{mW}$ of laser power yields very tight traps $150\mathrm{nm}$ above a waveguide with trap vibrational frequencies $\sim 1\mathrm{MHz}$ and vibrational ground state sizes $\sim 10\mathrm{nm}$. The arrays are scalable and allow addressing of individual sites for quantum logic operations.

Figure 1

(Color online) 2D optical lattice formed by interfering waveguide modes. (a) Schematic diagram of TE0 and TE1 modes interfering in a planar waveguide. The resulting 2D traps confine atoms along $y$ and $z$. (b) For laser powers of $1\mathrm{mW}$ (TE0) and $0.042\mathrm{mW}$ (TE1), the $E_x$ components of the TE0 (dashed line) and TE1 (dotted line) modes interfere (dash-dotted line) to form a nodal line $150\mathrm{nm}$ above the surface. The solid line (right axis) shows the potential energy of a Rb atom above the surface for $\Delta =1000\Gamma$. (c) Crossing two of the fields shown in (a) leads to a square array of 3D traps $150\mathrm{nm}$ above the surface, with a spacing of $0.98\mu \mathrm{m}$.

Figure 2

(Color online) 1D translatable array of 3D traps above a ridge waveguide formed by interfering two modes.

Figure 3

Trap contours (a) in the $x\text{‐}y$ plane and (b) in the $y\text{‐}z$ plane for one of the microtraps $(z*=0)$ of Fig. 2. For the laser intensities in the text, $\Delta U∕k_B=150\mu \mathrm{K}$, between contours.