# Hannover 2010 – wissenschaftliches Programm

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# Q: Fachverband Quantenoptik und Photonik

## Q 24: Quantum Gases: Mixtures and Spinor Gases

### Q 24.3: Vortrag

### Mittwoch, 10. März 2010, 11:00–11:15, E 001

**Excitation modes of a parametric amplifier for matter waves** — Carsten Klempt^{1}, Oliver Topic^{1}, Garu Gebreyesus^{2}, •Manuel Scherer^{1}, Bernd Lücke^{1}, Frank Deuretzbacher^{2}, Phillip Hyllus^{2}, Wolfgang Ertmer^{1}, Luis Santos^{2}, and Jan Arlt^{1} — ^{1}Institut für Quantenoptik, Leibniz Universität Hannover — ^{2}Institut für theoretische Physik, Leibniz Universität Hannover

Matter wave optics with ultracold atoms has reached the point where non-classical states can be prepared and their fascinating properties can be explored. In optics, parametric down conversion is routinely used to generate light with squeezed observables as well as highly entangled photon pairs. The applications of these non-classical states range from fundamental tests of quantum mechanics to improved interferometers and quantum computation. Therefore, it is of great interest to realize such non-classical states with matter waves. Bose-Einstein condensates with non-zero spin can provide a mechanism analogous to parametric down conversion, thus enabling the generation of non-classical matter waves. We have observed magnetic field dependent spin resonances where the spin dynamics is dramatically enhanced. On these resonances, a parametric amplification process produces entangled atom pairs in excited spatial modes which are similar to the modes of a classical membrane with fixed boundary conditions. Intriguingly, these spatial modes can carry orbital angular momentum. A first analysis shows that the system may serve as a source of atomic Bell pairs with entangled angular momentum states, possibly allowing for Bell type measurements with neutral atoms.