Enhancement of Rydberg atom interactions using dc and ac Stark shifts
Parisa Bohlouli-Zanjani
This thesis reports the use of both dc and ac electric fi eld induced resonant \nenergy transfer, RET, between cold Rydberg atoms as a useful tool for enhancement \nof interatomic interactions. A general technique for laser frequency stabilization and \nits suitability for Rydberg atom excitation is also demonstrated. \nRET between cold Rydberg atoms was used to determine Rydberg atom energy \nlevels. The ⁸⁵Rb atoms are laser cooled and trapped in a magneto-optical trap. \nFor energy level determination experiment, atoms were optically excited to 32d₅/₂ \nRydberg states. The two-atom process 32d₅/₂ + 32d₅/₂ → 34p₃/₂+30g is resonant at \nan electric fi eld of approximately 0.3 V/cm through dipole dipole interaction. The \nexperimentally observed resonant fi eld, together with the Stark map calculation is \nused to make a determination of the ⁸⁵Rb ng-series quantum defect to be ⵒg(n = \n30) = 0.00405(6). \nThe ac Stark eff ect was also used to induce RET between cold Rydberg atoms. \nWhen a 28.5 GHz dressing field was set at speci fic fi eld strengths, the two-atom \ndipole-dipole process 43d₅/₂ + 43d₅/₂ → 45p₃/₂ + 41f was dramatically enhanced, \ndue to induced degeneracy of the initial and final states. This method for enhancing \ninteractions is complementary to dc electric- field-induced RET, but has more \n \nflexibility due to the possibility of varying the applied frequency. At a dressing field \nof 28.5 GHz all of the participating levels (43d₅/₂, 45p₃/₂ and 41f) show signi cant \nshifts and these give a complicated series of resonances. An oscillating electric \nfi eld at 1.356 GHz was also used to promote the above RET process where the \natoms are initially excited to the 43d₅/₂ Rydberg states. The ac fi eld strength was \nscanned to collect RET spectra. Di fferent resonances were observed for diff erent \nmagnetic sublevels involved in the process. Compared to the higher dressing field \nfrequency of 28.5 GHz, the choice of dressing frequency of 1.356 GHz, which is \nslightly blue detuned from the 41f - 41g transition, and structure of the spectra \nmay be understood, by analogy with the dc field case.
•May 19, 2010•1 citation