Studies on the atom-photon interactions in radiofrequency spectroscopy

André Schirotzek, Yong-il Shin, Christian H. Schunck +1 more

J. W. Watson

K Luksch, E Bentine, A J Barker +4 more

Abstract We dress atoms with multiple-radiofrequency (RF) fields and investigate the spectrum of transitions driven by an additional probe field. A complete theoretical description of this rich spectrum is presented, in which we find allowed transitions and determine their amplitudes using the resolvent formalism. Experimentally, we observe transitions up to sixth order in the probe field using RF spectroscopy of Bose–Einstein condensates trapped in single- and multiple-RF-dressed potentials. We find excellent agreement between theory and experiment, including the prediction and verification of previously unobserved transitions, even in the single-RF case.

Ana Predojević, Morgan W. Mitchell

Y -Q Liu, D. Kaiser, Gebhard von Oppen

Anticrossings of the 1s5d and 1s6d 1 Lambda and 3 Lambda Stark sublevels of He I were investigated using radiofrequency spectroscopy. Single and multiple photon transitions were induced and detected after excitation of thermal He atoms by 10-20 keV ion impact. The energy separations of closest approach of four 1s5d and two 1s6d anticrossings were deduced from the resonance signals.

Raghavan K. Easwaran

In this thesis, I describe the spectroscopic investigations and preliminary results of evaporative cooling of rubidium atoms done on a magnetic trap dressed with a radiofrequency field. Unlike the case of a static magnetic trap, where a single radiofrequency photon is used to outcouple atoms we have demonstrated that a multiphoton transition is necessary. This transitions are nearly resonant with the energy spacing of the radiofrequency dressed states. The evaporation efficiency is not the same for all the observed transitions: the transition involving a two photon process is more efficient compared to the others. Preliminary results of evaporative cooling in a radiofrequency dressed trap are discussed. The quantum degeneracy is not reached as it is difficult to reach thermalization due to the strong anisotropy in the trap. A way to render the evaporative cooling more efficient is to increase the horizontal oscillation frequencies. Finally, we discuss a method to load the atoms into a radiofrequency dressed quadrupole trap, leading to large oscillation frequencies in the horizontal directions.