Efficient and Robust Initialization of a Qubit Register with Fermionic Atoms

We show that fermionic atoms have crucial advantages over bosonic atoms in terms of loading in optical lattices for use as a possible quantum computation device. After analyzing the change in the level structure of a nonuniform confining potential as a periodic potential is superimposed to it, we show how this structure combined with the Pauli principle and fermion degeneracy can be exploited to create unit occupancy of the lattice sites with very high efficiency.

Figure 1

Energy levels relative to the ground state $E_0$ as a function of the optical potential depth $s$, for a harmonic confinement with $\hslash \omega =E_r/(2{\pi }^2)$ and $z_0=d/3$.

Figure 2

Spatial position and extension of the eigenfunctions versus the corresponding eigenvalues for $s=1.2$ (a) and $s=12$ (b). Density profiles calculated for a number of atoms such that ${ϵ}_F=E_r$ at $s=0$, for $s=1.2$ (c), and $s=12$ (d). The confining potential is the same as in Fig. 1.

Figure 3

On the right-hand side we show the localization of the lowest eigenfunctions for $s=12$ for the same harmonic confinement as in Fig. 1. On the left-hand side, the eigenfunctions are shown for a V-shaped confinement $V=|z-z_0|E_r/(2{\pi }^{2}d)$. The V-shaped potential is chosen to have the same slope as the harmonic one at $z=4d$.