Radiative lifetime measurements of rubidium Rydberg states

Abstract

Abstract. We have measured the radiative lifetimes of ns, np and nd Rydberg states of rubidium in the range 28 ≤ n ≤ 45. To enable long-lived states to be measured, our experiment uses slow-moving (∼100 µK) 85 Rb atoms in a magnetooptical trap (MOT). Two experimental techniques have been adopted to reduce random and systematic errors. First, a narrow-bandwidth pulsed laser is used to excite the target nℓ Rydberg state, resulting in minimal shot-to-shot variation in the initial state population. Second, we monitor the target state population as a function of time delay from the laser pulse using a short-duration, millimetre-wave pulse that is resonant with a one-or two-photon transition to a higher energy "monitor state", n ′ ℓ ′ . We then selectively field ionize the monitor state, and detect the resulting electrons with a micro-channel plate. This signal is an accurate mirror of the nℓ target state population, and is uncontaminated by contributions from other states which are populated by black body radiation. Our results are generally consistent with other recent experimental results obtained using a method which is more prone to systematic error, and are also in excellent agreement with theory.

Photoionization rates of Cs Rydberg atoms in a 1064-nm far-off-resonance trap

“…The experimental lifetimes in the control experiment agree well with the predictions from [22], which suggests that we are also in agreement with experimental results for Rb [4][5][6]20] and lower-lying states of Cs [21]. Consistency with theoretical calculations and experimental work of other groups gives us confidence that the depopulation rates obtained in the MOT control experiment are valid and may safely be used to obtain photoionization rates in the 1064 nm FORT experiment.…”

“…The depopulation rates due to spontaneous emission and blackbody radiation are in agreement with recent calculations [22] and are thus in agreement with experimental results for lower-lying states of Rb [4][5][6]20] and Cs [21]. There is no systematic photoionization experiment with which to compare to our data, but the photoionization rates observed here are consistent with calculations following [15,24].…”

An experimental and theoretical guide to strongly interacting Rydberg gases

“…The first sum is limited to states with energies below the Rydberg state and the second sum runs over all allowed dipole transitions, however neglecting transitions to ionized states. The actual measurement of the radiative lifetime by delayed field ionization and detection of remaining Rydberg states is quite involved since one has to distinguish the Rydberg state in question from energetically close by states, which are likely to be populated by blackbody radiation [66]. Here this problem has been avoided by a state sensitive detection scheme.…”

Decoherence in Excited Atoms by Low-Energy Scattering

“…These cases represent common circumstances for atoms to be exposed to, and cover a fair range of energy densities. The time scale of the plot comprise periods that are much larger than the radiative lifetimes of Rydberg atoms [21]. In experiments, it should not be expected to directly see the loss in population due to the proposed effect, but rather a deviation in the decay curves due to spontaneous emission and other known perturbation sources.…”