An ion in a sea of ultracold neutral atoms
Control of Quantum Correlations in Tailored Matter
SFB/TRR 21 - Stuttgart, Ulm, Tübingen
The project is financially support by the Deutsche Forschungsgemeinschaft
We study the fundamental interactions of a single, trapped, laser-cooled Ba+ ion with ultracold 87Rb atoms. This experimentally unexplored terrain offers a multitude of fascinating experiments on the quantum level.
Here is a list of topics we would like to investigate in the near future:
- Inelastic and elastic cold collisions between atoms and ions
(Charge transfer, long range 1/r4 potential, huge scattering lengths)
- Ultracold chemistry with neutral atoms and ions
(charged, ultracold molecules)
- Demonstrate the formation of a predicted mesoscopic molecular bound state
(see R. Cote et al., PRL 89, 093001 (2002) )
- Study polaronic physics of charged impurities in the BEC
(dressing of ions, screening and tuning of interaction, effective mass, polaron binding energy)
- Controlled entanglement of single atoms and ions
(using a Mott insulator state of atoms in an optical lattice)
The Experimental Setup
We have completed setting up the experimental apparatus. It features a MOT chamber for initial laser cooling of the 87Rb atoms which are then magnetically transferred into a BEC chamber. Here, the Rb BEC is produced via forced evaporative cooling. With an optical standing wave the condensate is then transported into an ion trap chamber where a single Ba+ ion is located in a linear Paul trap.
The ion trap chamber features a linear Paul trap specifically designed to allow for the insertion of a standing wave dipole trap transporting an ultracold cloud of neutral atoms to the position of the ion. An objective lens system is installed inside the vacuum chamber facilitating efficient simultaneous flourescence imaging of the ion and absorption imaging of the atomic cloud.
At the beginning of 2010, we have for the first time observed cold atom-ion collisions (arXiv:1007.4717). On February 22nd, we have moved our apparatus from Innsbruck to Ulm. Recently, we have trapped strings of 138Ba ions for the first time here in Ulm. Also, we are again able to produce 87Rb Bose-Einstein condensates in our science chamber consisting of up to 105 atoms.