Pushing Around Cold Trapped Ions

We report on our work towards fast quantum logic gates in trapped atomic ions using strong laser fields to coherently "push" ions, following the ideas of Cirac and Zoller [Nature 404, 579 (2000)]. The scheme involves entanglement of trapped ion qubits by an internal state-dependent dipole force creating spatial superpositions, or "Schrödinger cat" states of the associated ion. Initial experiments are conducted with Cd^+ ions confined in an asymmetric rf quadrupole trap. The dipole force is provided by a frequency-quadrupled pulsed Nd:YAG laser at 266nm. We report on our progress in pushing laser-cooled ions with this laser, and the prospects of applying spin-dependent forces for future entangling logic gates in this system. This work is supported by NSA and ARDA under ARO contract DAAD19-01-1-0667 and the NSF-ITR program.