Alkaline-Earth-Metal Atoms as Few-Qubit Quantum Registers

We propose and analyze a novel approach to quantum information processing, in which multiple qubits can be encoded and manipulated using electronic and nuclear degrees of freedom associated with individual alkaline-earth-metal atoms trapped in an optical lattice. Specifically, we describe how the qubits within each register can be individually manipulated and measured with subwavelength optical resolution. We also show how such few-qubit registers can be coupled to each other in optical superlattices via conditional tunneling to form a scalable quantum network. Finally, potential applications to quantum computation and precision measurements are discussed.

Figure 1

(a) On the example of ${}^{171}\mathrm{Yb}$ ($I=1/2$) in the Paschen-Back regime for state ${}^{1}P_1$, relevant alkaline-earth-like level structure. (b) Interregister gate based on conditional resonant tunneling.

Figure 2

Nuclear-spin-preserving electronic-qubit detection. (a) ${}^{87}\mathrm{Sr}$ ($I=9/2$) in the Paschen-Back regime (the shift $-g_I{\mu }_N{m}_{I}B$ not shown). (b) On the example of ${}^{171}\mathrm{Yb}$ ($I=1/2$), dark-state-based spatial selectivity [19].