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Dr. Andrea Alberti

Institut für Angewandte Physik der Universität Bonn

Thursday, September 27th, 2012 at 11:00:00 AM  

Conference room Querzoli - LENS - via Nello Carrara 1 - Sesto Fiorentino (Florence)

Published on-line at 03:42:05 PM on Wednesday, September 19th, 2012

Interferometers, quantum walks and Bloch oscillations

Digital atom interferometry for single-atom force sensors and quantum (random) walk implementations.

Coherent control and delocalization of single trapped atoms constitute powerful new resources for quantum technologies. We will report on a digital atom interferometer employing discrete-time quantum operations to program the interfering paths of individual atoms (see 10.1073/pnas.1204285109). By applying about 100 operations, we demonstrated coherent splitting of a single atom in a spin-dependent optical lattice by more than 10 μm. Concerning its application as a single-atom force sensor, we showed a sensitivity to external potential gradients of 5 x 10-4 in units of gravitational acceleration g.

We use the same toolbox of operations developed for the digital atom interferometer to implement quantum walks, which realize the quantum counterpart of well-known classic random walks. Owing to their discrete-time quantum nature, these systems are inherently flexible and can be employed to simulate other physical mechanisms. To demonstrate their potential, we have recently realized an electric quantum walk, which mimics the behavior of a charged particle in a periodic potential in the presence of an electric field. We reproduced the characteristic mechanism of Bloch oscillations, and we identified features unique of a discrete-time system of period τ, where the commensurability of τ-1 with the Bloch frequency shows a dramatic enhancement of the Landau-Zener tunneling rate.

For further informations, please contact Prof. Guglielmo Tino.