Quantum systems engineering

Abstract:

We review recent theoretical advances in cold atom physics concentrating on strongly correlated cold atoms in optical lattices. We discuss recently developed quantum optical tools for manipulating atoms and show how they can be used to realize a wide range of many body Hamiltonians. Then, we describe connections and differences to condensed matter physics and present applications in the fields of quantum computing and quantum simulations. Finally, we explain how defects and atomic quantum dots can be introduced in a controlled way in optical lattice systems. © 2004 Elsevier Inc. All rights reserved.

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.