| dc.description.abstract | This thesis reports the use of both dc and ac electric fi eld induced resonant
energy transfer, RET, between cold Rydberg atoms as a useful tool for enhancement
of interatomic interactions. A general technique for laser frequency stabilization and
its suitability for Rydberg atom excitation is also demonstrated.
RET between cold Rydberg atoms was used to determine Rydberg atom energy
levels. The ⁸⁵Rb atoms are laser cooled and trapped in a magneto-optical trap.
For energy level determination experiment, atoms were optically excited to 32d₅/₂
Rydberg states. The two-atom process 32d₅/₂ + 32d₅/₂ → 34p₃/₂+30g is resonant at
an electric fi eld of approximately 0.3 V/cm through dipole dipole interaction. The
experimentally observed resonant fi eld, together with the Stark map calculation is
used to make a determination of the ⁸⁵Rb ng-series quantum defect to be ⵒg(n =
30) = 0.00405(6).
The ac Stark eff ect was also used to induce RET between cold Rydberg atoms.
When a 28.5 GHz dressing field was set at speci fic fi eld strengths, the two-atom
dipole-dipole process 43d₅/₂ + 43d₅/₂ → 45p₃/₂ + 41f was dramatically enhanced,
due to induced degeneracy of the initial and final states. This method for enhancing
interactions is complementary to dc electric- field-induced RET, but has more
flexibility due to the possibility of varying the applied frequency. At a dressing field
of 28.5 GHz all of the participating levels (43d₅/₂, 45p₃/₂ and 41f) show signi cant
shifts and these give a complicated series of resonances. An oscillating electric
fi eld at 1.356 GHz was also used to promote the above RET process where the
atoms are initially excited to the 43d₅/₂ Rydberg states. The ac fi eld strength was
scanned to collect RET spectra. Di fferent resonances were observed for diff erent
magnetic sublevels involved in the process. Compared to the higher dressing field
frequency of 28.5 GHz, the choice of dressing frequency of 1.356 GHz, which is
slightly blue detuned from the 41f - 41g transition, and structure of the spectra
may be understood, by analogy with the dc field case. | en |
