Great recognition for a team of theoretical physicists from Oldenburg and experimentalists from Pisa: The American Physical Society (APS) has classified a paper published jointly by Dr Andre Eckart (now in Barcelona), Prof. Dr Martin Holthaus (Condensed Matter Theory Group at the University of Oldenburg) and their Italian colleagues entitled "Exploring dynamic localisation with a Bose-Einstein condensate" (Phys. Rev. A 79, 013611 (2009)) as a "highlight" and reported on it in its series "Physics - spotlighting exceptional research".
(physics.aps.org/)

The oscillating body of a pendulum, which is brought over the suspension point of the pendulum and then released, falls immediately unless the pendulum is subjected to a time-periodic force that can stabilise it in the inverted position.

A similar effect occurs in quantum mechanics: The wave packet of a particle travelling on a periodic lattice normally propagates over the entire lattice - unless a time-periodic force is acting that can permanently hold the particle in one place. This effect, which has been known as "dynamic localisation" since its prediction 22 years ago, has now been observed by their experimental partners in Pisa with Bose-Einstein condensates in shaken optical lattices at the suggestion of the Oldenburg theorists.

In their publication, the team explains that this observation represents a milestone on the way to a new form of "quantum engineering": An electron moving in the periodic potential of a lattice is described by the famous Bloch waves of solid-state physics. Ultracold atoms in shaken optical lattices, on the other hand, sense the spatial
periodicity of the lattice AND the temporal periodicity of the shaking, so that novel quantum states emerge, which the authors call "spatiotemporal Bloch waves". Because one axis of their lattice does not extend in space as usual, but in time, these states can be systematically manipulated and controlled by, for example, simply changing the amplitude or frequency of the shaking. This fact not only explains the dynamic localisation, but could also lead to further novel applications - the team is staying on the ball.

Contact: Pro.Dr Martin Holthaus, Institute of Physics, Tel. 0441/798-3960

E-Mail:holthaus@theorie.physik.uni-oldenburg.de