Quantum information processing in optical lattices and magnetic microtraps

Abstract

We review our experiments on quantum information processing with neutral atoms in optical lattices and magnetic microtraps.Atoms in an optical lattice in the Mott insulator regime serve as a large qubit register. A spindependent lattice is used to split and delocalize the atomic wave functions in a controlled and coherent way over a defined number of lattice sites. This is used to experimentally demonstrate a massively parallel quantum gate array, which allows the creation of a highly entangled many-body cluster state through coherent collisions between atoms on neighbouring lattice sites.In magnetic microtraps on an atom chip, we demonstrate coherent manipulation of atomic qubit states and measure coherence lifetimes exceeding one second at micron-distance from the chip surface. We show that microwave near-fields on the chip can be used to create state-dependent potentials for the implementation of a quantum controlled phase gate with these robust qubit states. For single atom detection and preparation, we have developed high finesse fiber Fabry-Perot cavities and integrated them on the atom chip. We present an experiment in which we detected a very small number of cold atoms magnetically trapped in the cavity using the atom chip.

Macroscopic quantum information processing using spin coherent states

“…[11,12]. Here we discuss an alternative all-optical method for single qubit rotations which naturally fits into the scheme for two qubit rotations (discussed below) [31].…”

Steady-state entanglement in a double-well Bose-Einstein condensate through coupling to a superconducting resonator

“…The operators F ± and F z , and S (+) ± and S (+) z in Eqs. (20) to (22) generate an su(3) algebra [39]. In the limit of large N , we can apply the HPT to the operators:…”

“…Here we consider the two hyperfine states |e and |g of 87 Rb with the transition frequency 2π × 6.8 GHz [6]. The coherence times [19,20] of these hyperfine spin states (|e and |g ) are much longer than both the time scales of tunneling and atom-photon interactions. Therefore, this system offers possibilities for the study of how the tunnel couplings between the two spatially separated condensates affect the atom-photon dynamics.…”

Trapping and Manipulation of Isolated Atoms Using Nanoscale Plasmonic Structures

“…Simultaneously, the guided surface plasmon modes of the nanotip allow the atom to be optically manipulated, or for fluorescence photons to be collected, with very high efficiency. Finally, we analyze the surface forces and heating and decoherence rates acting on the trapped atom.Much interest has recently been directed towards hybrid systems that integrate isolated atomic systems with solid-state devices [1,2,3,4]. These efforts are aimed at combining the best of both worlds, namely the excellent coherence and control associated with isolated atoms, ions and molecules, with the miniaturization and integrability associated with solid-state devices.…”

“…Much interest has recently been directed towards hybrid systems that integrate isolated atomic systems with solid-state devices [1,2,3,4]. These efforts are aimed at combining the best of both worlds, namely the excellent coherence and control associated with isolated atoms, ions and molecules, with the miniaturization and integrability associated with solid-state devices.…”