Towards trapping of circular Rydberg atoms

Controlling all the degrees of freedom of a simple system is an interesting goal both from a fundamental point of view and with a view to further applications, quantum information for example. We have started to build a new apparatus in order to trap circular Rydberg atoms in the vicinity of surface micro-fabricated devices. The primary source of Rubidium is a vertical atomic jet producing a flux of slow atoms. We demonstrate the possibility of conducting an experiment along the following lines. First, the atoms are captured inside a pumped Helium cryostat at the heart of which the experiment is carried out. A cold and dense Rubidium cloud is prepared using magnetic micro-chip techniques. Following an excitation process involving lasers and radio-frequency, a single circular Rydberg atom is obtained, due to the dipole blockade effect. This atom is finally confined in a dynamic electric trap exploiting the extreme polarizability of the relevant atomic states. A 'microwave dressing' technique reduces the difference in polarizability between two given levels, allowing the preservation of quantum coherencies over time scale of the order of a second. The atomic lifetime is also increased by spontaneous emission inhibition in the vicinity of metallic surfaces. Finally, the atomic internal state after interaction processes is measured via detection of the ionization electron using a superconducting transition-edge sensor. (author)