Hamburg 2009 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 63: Quanteninformation: Quantencomputer
Q 63.3: Talk
Friday, March 6, 2009, 14:30–14:45, VMP 6 HS-A
Demonstration of a geometric two ion/qubit phase gate on the radial modes of motion — •Thomas Huber1, Hector Schmitz2, Christian Schneider1, Martin Enderlein1, and Tobias Schaetz1 — 1Max-Planck-Institut für Quantenoptik — 2LMU München
Phonons in a linear chain of ions can provide interactions/a data bus between spins/qubits for quantum simulations(QS)/computation(QC). So far, experimentalists only exploit the axial degree of freedom in linear traps, i.e. the phonons of the axial normal modes of motion. We want to open up the radial degrees of freedom, exploring the (dis)advantages with respect to QC and QS. For an increasing amount of ions it becomes, for example, more difficult to place the ions at the correct relative positions to experience identical laser phases of a standing or travelling axially propagating wave, which provides the conditional motional excitations. Pushing the ions radially renders the system insensitive to the mutual ion distance. Additionally, the frequencies of the radial modes can be adjusted to be similar. The required ground state cooling of all motional modes might hence be possible by one common cooling cycle. To calibrate our interactions for future QS, we implemented a two-qubit phase gate with a fidelity exceeding 90%. We are able to laser-cool five ions to the radial motional ground states, a first step towards simulations with increased amounts of ion spins required in QS of systems of interest, like the Bose-Hubbard Hamiltonian. It also gives perspectives to 2D lattices of spins provided in potential surface trap arrays.