High-Angular-Momentum States in Cold Rydberg Gases

Dutta, Subrata; Feldbaum, D.; Walz-Flannigan, Alisa; Guest, Jeffrey R.; Raithel, Georg

doi:10.1103/physrevlett.86.3993

Cited by 103 publications

(76 citation statements)

References 8 publications

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“…While the theoretical analysis of Robicheaux and Hanson [9] found this phenomenon to be caused by electron collisions with high-ᐉ Rydberg states (in other words, the same process that causes high-n population), Walz-Flannigan et al suggest that these states are populated as a by-product of Penning ionization enhanced by dipole-dipole interactions. On the other hand, we observed no signal that persisted for longer than ϳ100 s after the initial Rydberg state was populated by the laser, whereas an earlier paper from the Michigan group reported seeing electron emission for as long as 20 ms [15]. Some of the differences between our work and that from the University of Michigan are perhaps attributable to the fact that we normally have a small (1-2 %) background of thermal Rydberg atoms, which is completely absent in the Michigan apparatus.…”

Section: Rydberg Population Redistributioncontrasting

confidence: 45%

“…Cold atoms in a MOT excited to Rydberg states of principal quantum number with n Ͼ 30, were found to evolve spontaneously to plasma on a time scale of ϳ1 s, provided that the sample contained ϳ1% of hot ͑ϳ300 K͒ Rydberg atoms [14]. Soon after this work, a sample of purely cold Rydberg atoms was observed to ionize spontaneously, and electron emission from such a sample was observed for more than 20 ms after the excitation of the initial Rydberg state [15]. A similar phenomenon had been observed previously in a thermal sample of cesium Rydberg atoms by Vitrant et al [16] at a density a factor of 10 4 higher than those used in Refs.…”

Section: Introductionmentioning

confidence: 95%

“…A similar phenomenon had been observed previously in a thermal sample of cesium Rydberg atoms by Vitrant et al [16] at a density a factor of 10 4 higher than those used in Refs. [14] and [15]. The evolution of the cold Rydberg atoms into the plasma was described by the following scenario.…”

Section: Introductionmentioning

confidence: 99%

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Evolution dynamics of a dense frozen Rydberg gas to plasma

Noel

Robinson

et al. 2004

Phys. Rev. A

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Dense samples of cold Rydberg atoms have previously been observed to spontaneously evolve to a plasma, despite the fact that each atom may be bound by as much as 100 cm −1 . Initially, ionization is caused by blackbody photoionization and Rydberg-Rydberg collisions. After the first electrons leave the interaction region, the net positive charge traps subsequent electrons. As a result, rapid ionization starts to occur after 1 s caused by electron-Rydberg collisions. The resulting cold plasma expands slowly and persists for tens of microseconds. While the initial report on this process identified the key issues described above, it failed to resolve one key aspect of the evolution process. Specifically, redistribution of population to Rydberg states other than the one initially populated was not observed, a necessary mechanism to maintain the energy balance in the system. Here we report new and expanded observations showing such redistribution and confirming theoretical predictions concerning the evolution to a plasma. These measurements also indicate that, for high n states of purely cold Rydberg samples, the initial ionization process which leads to electron trapping is one involving the interactions between Rydberg atoms.

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Section: Rydberg Population Redistributioncontrasting

confidence: 45%

Section: Introductionmentioning

confidence: 95%

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Evolution dynamics of a dense frozen Rydberg gas to plasma

Noel

Robinson

et al. 2004

Phys. Rev. A

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“…This can be accomplished in a controlled manner by adding a small seed UNP, which introduces free electrons that quickly promote Rydberg electrons to higher angular momentum states through quasielastic -mixing electron-Rydberg collisions [63]. The cross section for this process when the velocity of the free electron is close to the classical orbital velocity of the Rydberg electron is very large [63]. Figure 2(b) shows how the presence of a relatively small "seed" UNP leads to a dramatic increase in the LIF signal.…”

Section: A Low-rydberg Atoms and The Effect Of An Unp Seedmentioning

confidence: 99%

Imaging the evolution of an ultracold strontium Rydberg gas

et al. 2013

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Clouds of ultracold strontium 5s48s 1 S 0 or 5s47d 1 D 2 Rydberg atoms are created by two-photon excitation of laser-cooled 5s 2 1 S 0 atoms. The spontaneous evolution of the cloud of low orbital angular momentum (low-) Rydberg states towards an ultracold neutral plasma is observed by imaging resonant light scattered from core ions, a technique that provides both spatial and temporal resolution. Evolution is observed to be faster for the S states, which display isotropic attractive interactions, than for the D states, which exhibit anisotropic, principally repulsive interactions. Immersion of the atoms in a dilute ultracold neutral plasma speeds up the evolution and allows the number of Rydberg atoms initially created to be determined.

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“…We want to emphasize that the excitation trapping described here is not due to state redistribution by collisions with ions [22] since we have verified that there are no ions produced during the short excitation time. Furthermore the excitation volume is too small to support avalanche ionization.…”

mentioning

confidence: 99%

Rabi Oscillations and Excitation Trapping in the Coherent Excitation of a Mesoscopic Frozen Rydberg Gas

et al. 2008

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We demonstrate the coherent excitation of a mesoscopic ensemble of about 100 ultracold atoms to Rydberg states by driving Rabi oscillations from the atomic ground state. We employ a dedicated beam shaping and optical pumping scheme to compensate for the small transition matrix element. We study the excitation in a weakly interacting regime and in the regime of strong interactions. When increasing the interaction strength by pair state resonances we observe an increased excitation rate through coupling to high angular momentum states. This effect is in contrast to the proposed and previously observed interaction-induced suppression of excitation, the so-called dipole blockade.PACS numbers: 03.65. Yz, 32.80.Pj, 32.80.Rm, 34.20.Cf, 34.60.+z Rydberg atoms, with their rich internal structure, have been in the focus of atomic physics for more than a century [1]. In the last decade Rydberg physics were extended to laser-cooled atomic gases which allowed the study of a frozen system with controllable, strong interactions and negligible thermal contributions. This has opened a wide field in both experiment and theory covering such diverse areas as resonant energy transfer [2,3], plasma formation [4,5], exotic molecules [6,7], and quantum random walks [8,9]. In addition, these frozen Rydberg systems have been proposed as a possible candidate for quantum information processing [10,11]. However, the coherent excitation of Rydberg atoms, an important prerequisite for quantum information protocols, has proven a challenging task. While Rabi oscillations between different Rydberg states have been demonstrated and thoroughly analyzed before [12], Rabi oscillations between the ground state and Rydberg states of atoms have not been observed directly so far, mainly owing to the small transition matrix element.In this Letter we report on the experimental realization and observation of Rabi oscillations between the ground and Rydberg states of ultracold atoms. We demonstrate how strong interatomic interactions influence the coherent excitation of a mesoscopic cloud of atoms. We show that an interaction-induced coupling to a larger number of internal states can be used to trap the excitation. Employed in a controlled way, this effect offers future applications in the experimental realization of quantum random walks with exciton trapping [9].Our experiments are performed with a magneto-optical trap (MOT) of about 10 7 87 Rb atoms at densities of 10 10 cm −3 and temperatures below 100 µK. Rydberg excitation is achieved with two counterpropagating laser beams at 780 nm and 480 nm (see Fig. 1). The laser at 780 nm is collimated to a waist of 1.1 mm ensuring a constant Rabi frequency of 2π × 55 MHz over the excitation volume as determined from Autler-Townes splittings [13]. The laser at 480 nm is referenced to a temperature stabilized Zerodur-resonator and its beam is shaped with a diffractive optical element that produces a flattop beam profile which is characterized with an adapted CCD camera with a spatial resolution of 5.6 µm. The m...

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High-Angular-Momentum States in Cold Rydberg Gases

Cited by 103 publications

References 8 publications

Evolution dynamics of a dense frozen Rydberg gas to plasma

Evolution dynamics of a dense frozen Rydberg gas to plasma

Imaging the evolution of an ultracold strontium Rydberg gas

Rabi Oscillations and Excitation Trapping in the Coherent Excitation of a Mesoscopic Frozen Rydberg Gas

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