© 2026 Aqora Quantum S.A.S.

Terms Privacy Legal Notice

Physical Review A

Ionization of Rydberg atoms by a precessing electric field of constant amplitude

C. H. Cheng, Thomas F. Gallagher

Published May 16, 2000• 7 citations

Abstract

We have studied in detail the continuous evolution from static field ionization to ionization by a circularly polarized microwave field by combining a z-polarized static field with a circularly polarized microwave field in the x-y plane. We have measured the ionization threshold for Na states of $27<~n<~50$ in the precessing total field ${F}_{t},$ as a function of its angle \ensuremath{\theta} from the z axis. For low n, ${F}_{t}\ensuremath{\cong}{1/16n}^{4},$ independent of \ensuremath{\theta}. For $n>~45,$ ${F}_{t}$ decreases from ${1/16n}^{4}$ to ${0.8/16n}^{4}$ as \ensuremath{\theta} is increased from 0\ifmmode^\circ\else\textdegree\fi{} to 25\ifmmode^\circ\else\textdegree\fi{}, and it remains at this value until $\ensuremath{\theta}=90\ifmmode^\circ\else\textdegree\fi{}.$ We also observe ionization at quite low values of ${F}_{t},$ which we attribute to resonantly enhanced ionization, with the resonances driven by a stray static field in the x-y plane.

DOI: 10.1103/physreva.61.063411

Related papers

Ionization of Rydberg atoms by a circularly polarized microwave field

Panmimg Fu, T. J. Scholz, J. M. Hettema +1 more

We report the first observation of the ionization of Rydberg atoms by a circularly polarized 8.5-GHz microwave field. The observed threshold field for ionization is E=1/16${\mathrm{n}}^{4}$, a value higher than that required for ionization by a linearly polarized microwave field. The origin of this threshold can be understood by transforming to a frame rotating at the microwave frequency. In the rotating frame no transitions occur, and level mixings alone are responsible for the ionization.

Physical Review Letters•Jan 29, 1990•87 citations

Microwave ionization of Na atoms in weak-to-strong static electric fields

C. Y. Lee, J. M. Hettema, Thomas F. Gallagher +1 more

We report measurements of the microwave ionization of Rydberg atoms as a function of static electric field, for static fields from zero to the classical ionization limit. The microwave-ionization threshold field shows clear structure as a function of the static field, in some static field regimes actually increasing as the static field is increased. The dependence of the microwave field can be understood by considering the dynamics of the levels in a temporally varying field.

Physical Review A•Dec 1, 1992•4 citations

IONIZATION OF RYDBERG ATOMS BY CIRCULARLY POLARIZED MICROWAVE FIELDS

Thomas F. Gallagher

In circularly polarized microwave fields of frequencies in the vicinity of 10 GHz ionization of Na Rydberg atoms occurs at a field E=1/16n4, up to principal quantum number n=50. This field is equal to the classical field for ionization and the static field required to ionize a Na atom. On the other hand, this field is far below the linearly polarized 10 GHz field required to ionize Na atoms, E=1/3n5. If the problem is transformed to a frame rotating with the microwave field, the field becomes a static field. In this case it is straightforward to calculate the ionization field classically. However, it is far lower than the experimentally observed field, a discrepancy which may be due to an angular momentum barrier.

Modern Physics Letters B•Feb 20, 1991•18 citations

Circularly and elliptically polarized microwave ionization of Na Rydberg atoms

C Y Lee, J. M. Hettema, C. H. Cheng +2 more

We have measured the 17.3 GHz circularly polarized microwave ionization (CPMI) threshold fields for Na Rydberg atoms and compared them to the previous 8.5 GHz measurements. In both cases the ionization fields are near for low n and fall below this value at high n. A small ellipticity in the polarization and a small static field in the plane of the rotating microwave field both lead to ionization at substantially lower fields, approaching . In addition, elliptically polarized microwave ionization (EPMI) of Rydberg atoms and CPMI in the presence of a small static field have much lower threshold fields for ionization and unexpected resonant peaks at microwave fields below the CPMI threshold fields are observed in both cases at 8, but not at 17, GHz. Sequences of resonant microwave transitions are proposed to explain these resonant structures.

Journal of Physics B Atomic Molecular and Optical Physics•Aug 14, 1996•2 citations

Resonances for Rydberg atoms in a precessing electric field of constant amplitude

Valentin N. Ostrovsky, Erik Horsdal-Pedersen

The quasienergy spectrum of hydrogenlike Rydberg atoms in a precessing electric field of constant amplitude is found in simple form. Resonant intrashell transitions occur for specific field values when a (small) additional static electric field perpendicular to the precession axis is present. Sequences of such transitions may enhance the microwave ionization of a Rydberg atom. C. H. Cheng and T. F. Gallagher [Phys. Rev. A 61, 063411 (2000)] recently observed a one-photon resonance of this type. We evaluate the widths of one-photon intrashell resonances, and develop a general approach to the N-photon case within the framework of a quasienergy representation.

Physical Review A•Mar 26, 2003•7 citations

Ionization of Na Rydberg atoms by a 79-GHz microwave field

Alexandr Arakelyan, Jirakan Nunkaew, Thomas F. Gallagher

We have measured the ionization fields for Na Rydberg states of $n\ensuremath{\ge}26$ by a 79-GHz microwave field. At low $n$, where the microwave frequency $\ensuremath{\omega}$ is one-third the classical Kepler frequency ${\ensuremath{\omega}}_{K}$, which is equal to the $1/{n}^{3}$ spacing between $n$ states, the ionization field is $\ensuremath{\approx}1/3{n}^{5}$, in atomic units. As $n$ is raised ${\ensuremath{\omega}}_{K}$ decreases, and the ionization field rises above $1/3{n}^{5}$, reaching a constant value when $\ensuremath{\omega}={\ensuremath{\omega}}_{K}$. At very high $n$, where $\ensuremath{\omega}>1/2{n}^{2}$, single photoionization is possible, and the measured rate agrees with the calculated value. These measurements, together with those done previously, connect the processes of field ionization and photoionization in Na. At low $n$ and radio frequencies ionization is simply field ionization, and at very high $n$ it occurs by photoionization, single-photon absorption. These measurements also show that microwave ionization of Rydberg atoms at 79 GHz results in significant populations' being left in the very high-lying states.

Physical Review A•Nov 17, 2016•19 citations

We have studied in detail the continuous evolution from static field ionization to ionization by a circularly polarized microwave field by combining a z-polarized static field with a circularly polarized microwave field in the x-y plane. We have measured the ionization threshold for Na states of

27<~n<~50

in the precessing total field

{F}_{t},

as a function of its angle \ensuremath{\theta} from the z axis. For low n,

{F}_{t}\ensuremath{\cong}{1/16n}^{4},

independent of \ensuremath{\theta}. For

n>~45,

{F}_{t}

decreases from

{1/16n}^{4}

to

{0.8/16n}^{4}

as \ensuremath{\theta} is increased from 0\ifmmode^\circ\else\textdegree\fi{} to 25\ifmmode^\circ\else\textdegree\fi{}, and it remains at this value until

\ensuremath{\theta}=90\ifmmode^\circ\else\textdegree\fi{}.

We also observe ionization at quite low values of

{F}_{t},

which we attribute to resonantly enhanced ionization, with the resonances driven by a stray static field in the x-y plane.

We report the first observation of the ionization of Rydberg atoms by a circularly polarized 8.5-GHz microwave field. The observed threshold field for ionization is E=1/16

{\mathrm{n}}^{4}

, a value higher than that required for ionization by a linearly polarized microwave field. The origin of this threshold can be understood by transforming to a frame rotating at the microwave frequency. In the rotating frame no transitions occur, and level mixings alone are responsible for the ionization.

In circularly polarized microwave fields of frequencies in the vicinity of 10 GHz ionization of Na Rydberg atoms occurs at a field E=1/16n4, up to principal quantum number n=50. This field is equal to the classical field for ionization and the static field required to ionize a Na atom. On the other hand, this field is far below the linearly polarized 10 GHz field required to ionize Na atoms, E=1/3n5. If the problem is transformed to a frame rotating with the microwave field, the field becomes a static field. In this case it is straightforward to calculate the ionization field classically. However, it is far lower than the experimentally observed field, a discrepancy which may be due to an angular momentum barrier.

We have measured the 17.3 GHz circularly polarized microwave ionization (CPMI) threshold fields for Na Rydberg atoms and compared them to the previous 8.5 GHz measurements. In both cases the ionization fields are near for low n and fall below this value at high n. A small ellipticity in the polarization and a small static field in the plane of the rotating microwave field both lead to ionization at substantially lower fields, approaching . In addition, elliptically polarized microwave ionization (EPMI) of Rydberg atoms and CPMI in the presence of a small static field have much lower threshold fields for ionization and unexpected resonant peaks at microwave fields below the CPMI threshold fields are observed in both cases at 8, but not at 17, GHz. Sequences of resonant microwave transitions are proposed to explain these resonant structures.

The quasienergy spectrum of hydrogenlike Rydberg atoms in a precessing electric field of constant amplitude is found in simple form. Resonant intrashell transitions occur for specific field values when a (small) additional static electric field perpendicular to the precession axis is present. Sequences of such transitions may enhance the microwave ionization of a Rydberg atom. C. H. Cheng and T. F. Gallagher [Phys. Rev. A 61, 063411 (2000)] recently observed a one-photon resonance of this type. We evaluate the widths of one-photon intrashell resonances, and develop a general approach to the N-photon case within the framework of a quasienergy representation.

We have measured the ionization fields for Na Rydberg states of $n\ensuremath{\ge}26$ by a 79-GHz microwave field. At low

n

, where the microwave frequency $\ensuremath{\omega}$ is one-third the classical Kepler frequency ${\ensuremath{\omega}}_{K}$, which is equal to the

1/{n}^{3}

spacing between

n

states, the ionization field is $\ensuremath{\approx}1/3{n}^{5}$, in atomic units. As

n

is raised ${\ensuremath{\omega}}_{K}$ decreases, and the ionization field rises above

1/3{n}^{5}

, reaching a constant value when $\ensuremath{\omega}={\ensuremath{\omega}}_{K}$. At very high

n

, where $\ensuremath{\omega}>1/2{n}^{2}$, single photoionization is possible, and the measured rate agrees with the calculated value. These measurements, together with those done previously, connect the processes of field ionization and photoionization in Na. At low

n

and radio frequencies ionization is simply field ionization, and at very high

n

it occurs by photoionization, single-photon absorption. These measurements also show that microwave ionization of Rydberg atoms at 79 GHz results in significant populations' being left in the very high-lying states.