Thursday, April 18, 2013

1304.4615 (Luigi Amico et al.)

Flux qubits with neutral currents in optical lattices    [PDF]

Luigi Amico, Davit Aghamalyan, H. Crepaz, F. Auksztol, R. Dumke, L. -C. Kwek
We study an experimentally feasible qubit system employing neutral currents. Our system is based on bosonic cold atoms trapped in ring-shaped optical lattice potentials. The lattice makes the system strictly one dimensional and it provides the infrastructure to realize a tunable ring-ring interaction. By breaking the Galilean invariance we demonstrate how atomic currents trough the lattice provide a realization of a qubit. We break Galilean invariance either by artificially creating a phase slip in a single ring, or by considering two homogeneous ring lattices, coupled by tunneling interaction. The Hamiltonian of the system effectively leads to a washboard potential in the phase representation, tilted by the applied 'flux'. The single qubit infrastructure is experimentally investigated with tailored optical potentials. An experimentally feasible scheme of the two-ring-qubit is discussed. In this case, the dynamics is demonstrated to show macroscopic quantum self trapping. Time-of-flight expansion maps the pattern of atomic currents into detectable atomic density distributions. Based on our analysis, we provide viable protocols to initialize, address, and read-out the qubit.
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