Prof Dieter Jaksch

Abstract:

The possibility of observing energy decoherence due to quantum gravity, corresponding to a discretization of time at the Planck scale, is discussed. The observable effects are governed by the relative phase between the two systems and are unchanged by energy decoherence that acts globally on system and phase reference together. It was suggested that the basic reason for the need for a phase reference is the fact that macroscopic objects have very little energy coherence. Energy decoherence acting locally below the micrometer scale is already ruled out by atom interferometer.

Abstract:

We propose a scheme utilizing a quantum interference phenomenon to switch the transport of atoms in a 1D optical lattice through a site containing an impurity atom. The impurity represents a qubit which in one spin state is transparent to the probe atoms, but in the other acts as a single atom mirror. This allows a single-shot quantum nondemolition measurement of the qubit spin.

Abstract:

We review novel methods for the investigation, control and manipulation of neutral atoms in optical lattices. These setups allow unprecedented quantum control over large numbers of atoms and thus are very promising for applications in quantum information processing. After introducing optical lattices we discuss the superfluid (SF) and Mott insulating (MI) states of neutral atoms trapped in such lattices and investigate the SF-MI transition as observed experimentally recently. In the second part of the paper we give an overview of proposals for quantum information processing and show different ways to entangle the trapped atoms, in particular the usage of cold collisions and Rydberg atoms. Finally, we discuss briefly the implementation of quantum simulators, entanglement enhanced atom interferometers, and ideas for robust quantum memory in optical lattices.