Population Trapping in Extremely Highly Excited States in Microwave Ionization

Noel, Michael W.; Griffith, W. M.; Gallagher, T. F.

doi:10.1103/physrevlett.83.1747

Cited by 17 publications

(10 citation statements)

References 11 publications

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“…The effect of the microwave field is only to superimpose a fast oscillation at the microwave frequency on the slower orbital motion. Such high-lying states have been observed previously subsequent to exposure of Rydberg atoms to short microwave pulses [26]. More generally, Rydberg states can be found after exposure of atoms to fields far in excess of the static fields required for ionization [27,28].…”

Section: Discussionsupporting

confidence: 58%

Connecting field ionization to photoionization via 17- and 36-GHz microwave fields

et al. 2010

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Here we present experimental results connecting field ionization to photoionization in Li Rydberg atoms obtained with 17-and 36-GHz microwave fields. At a low principal quantum number n, where the microwave frequency ω is much lower than the classical, or Kepler frequency, ω K = 1/n 3 , microwave ionization occurs by field ionization, at E = 1/9n 4. When the microwave frequency exceeds the Kepler frequency, ω > 1/n 3 , the field required for ionization is independent of n and given by E = 2.4ω 5/3 , in agreement with dynamic localization models, which cross over to a Fermi's Golden Rule approach at the photoionization limit. A surprising aspect of our results is that when ω ≈ 1/2n 2 , the one-and multiphoton ionization rates are similar, and even at the lowest microwave powers, all are 10 times lower than the perturbation theory rate calculated for single-photon ionization. Further, we show that when the Rydberg atoms are excited in the presence of the microwave field, the probability of an atom's being bound at the end of the microwave pulse passes smoothly across the limit. This microwave stimulated recombination to bound Rydberg states can be well described by a simple classical model. More generally, these results suggest that the problem of a Rydberg atom coupled to a high-frequency microwave field is similar to the problem of interchannel internal coupling in multilimit atoms, a problem well described by quantum defect theory.

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Section: Discussionsupporting

confidence: 58%

Connecting field ionization to photoionization via 17- and 36-GHz microwave fields

et al. 2010

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“…Time-resolved studies of the spatial distributions of Rydberg wave packets have been conducted extensively. Many different optical tools have been used, such as ultraviolet laser pulses [13][14][15], half-cycle pulses [16][17][18], single-cycle pulses [19,20], microwaves [21][22][23], and others. Compared with the other methods, the ionization properties of single-cycle pulses on Rydberg wave packets have not been widely studied.…”

Section: Introductionmentioning

confidence: 99%

Ionization from Rydberg atoms and wave packets by scaled terahertz single-cycle pulses

Wang

Robicheaux

2019

Phys. Rev. A

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The strong field ionization behavior when a Rydberg atom is exposed to a terahertz singlecycle pulse is studied. Fully three-dimensional time-dependent Schrödinger equation and classical trajectory Monte Carlo calculations are performed. Results from stationary eigenstates and Rydberg wave packets are presented, and it is found that the ionization properties can be different for the two cases. All of the pulse parameters and physical quantities are scaled versus the principal quantum number, n. The ionized electron's scaled radial, energy, and angular distributions are investigated for different n, and the quantum results are interpreted using a semiclassical method. The scaling relations of quantum interference amplitudes are discussed.

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“…When laser excited atoms are exposed to an intense microwave or laser field, a certain fraction will be trapped in highly excited states for a long time [1][2][3][4][5], leading to their classification as quasi-stable states. Classically, the electrons in quasi-stable states derive their stability through orbiting in a weakly bound trajectory where they have little chance to absorb enough energy to escape [3,4,6].…”

Section: Introductionmentioning

confidence: 99%

Coherence and quasistable states in a strong infrared field

Zhong¹,

Robicheaux²

2016

Phys. Rev. A

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We study the quasi-stability of UV-pulse-train-excited H atoms in a strong infrared (IR) laser as a function of the phase delay of the UV-pulse-train relative to the IR laser. The UV-pulse-train contains two frequency components. When the two components have frequencies separated by two IR photons, the population of surviving electrons is modulated by up to ten percent. When electrons are excited to right above or below the threshold, the survival probabilities have inverted phase delay dependence which can be explained classically. When the two frequencies are one IR-photon apart, the angular symmetry of the quasi-stable electrons is broken, and the asymmetry is also controlled by the phase delay. The asymmetrical distribution can be observed while the IR is on and smoothly evolves to a nonzero asymmetry that only weakly depends on the duration of the IR field.

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Population Trapping in Extremely Highly Excited States in Microwave Ionization

Cited by 17 publications

References 11 publications

Connecting field ionization to photoionization via 17- and 36-GHz microwave fields

Connecting field ionization to photoionization via 17- and 36-GHz microwave fields

Ionization from Rydberg atoms and wave packets by scaled terahertz single-cycle pulses

Coherence and quasistable states in a strong infrared field

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