[MOS] February 28, 2012

[Zina M Queen]

Seminar on






Modern Optics and Spectroscopy

Electronic coherence in a gas of dipole-dipole coupled Rydberg atoms

Robert Jones,
University of Virginia
Tuesday, February 28, 2012

12:00 – 1:00 p.m.
The great spatial extent of highly-excited Rydberg atoms endows them with large dipole moments and electric polarizabilities, making them extremely sensitive to external fields and neighboring atoms. We use cold diffuse ensembles of Rydberg atoms to explore few-and many-body dipole-dipole interactions at long range. We have recently demonstrated a novel time-domain method to probe coherence in ensembles where the dipole-dipole couplings are nearly resonant. In our experiments, short laser pulses create coherent superpositions of few-atom Rydberg eigenstates which evolve under the influence of pulsed electric field sequences. The field pulses coherently enhance the probability for finding atoms in $np$, rather than initially excited $ns$ states. The persistence of the enhancement indicates coherence times exceeding 10$\mu$s, comparable to the spontaneous emission lifetime of the atoms and roughly two orders of magnitude longer than macroscopic dephasing times in the same system. Simulations indicate that atom motion is primarily responsible for the eventual loss of coherence. Beyond the coherence measurement, the experiments provide some evidence for coherent control of the few-body system in the form of pulsed-field enhancement of the coherence time.


Grier Room, MIT Bldg 34-401
Refreshments served after the lecture
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