QUROPE Quantum Information Processing and Communication in Europe

We study the ground-state properties of bosons loaded into the 

Collective behavior in many-body systems is the origin of many fascinating phenomena in nature ranging from swarms of birds and modeling of human behavior to fundamental magnetic properties of solids. We report on the first observation of collective spin dynamics in an ultracold Fermi sea with large spin: We observe long-lived and large-amplitude coherent spin oscillations, driven by local spin interactions.

We describe a simple technique for generating a cold-atom lattice pierced by a uniform magnetic field. Our method is to extend a one-dimensional optical lattice into the "dimension" provided by the internal atomic degrees of freedom, yielding a synthetic 2D lattice. Suitable laser-coupling between these internal states leads to a uniform magnetic flux within the 2D lattice.

The paper, authored by Tomasz Sowiński, Mateusz Łacki, Omjyoti Dutta, Joanna Pietraszewicz, Piotr Sierant, Mariusz Gajda, Jakub Zakrzewski, Maciej Lewenstein, has been published on the 19th November 2013 on Phys. Rev. Lett. 111, 215302 (2013)

The paper, authored by Y. Lin, J. P. Gaebler, F. Reiter, T. R. Tan, R. Bowler, A. S. Sørensen, D. Leibfried, D. J. Wineland, has been published (online) on the 24th November 2013 on Nature 504, 415–418 doi:10.1038/nature12801

The Chalmers SOLID group recently published an article in Physical Review Letters in which they show, in the context of single-photon detection, that an atomic three-level model for a transmon in a transmission line does not support the predictions of the nonlinear polarizability model known as the cross-Kerr effect.

The group led by Lieven Vandersypen at TU-Delft recently published a paper in Nature Nanotechnology in which they show that two distant sites in an electrostatically defined quantum dot array can be tunnel-coupled directly. The coupling is mediated by virtual occupation of an intermediate site, with a strength that is controlled via the energy detuning of this site.

In a recent publication in Nature Physics the group led by SOLID partner Ronald Hanson realized a two-qubit parity measurement on nuclear spins localized near a nitrogen-vacancy centre in diamond by exploiting an electron spin as a readout ancilla. The measurement enabled the group to project the initially uncorrelated nuclear spins into maximally entangled states.