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We report measurements of the ratio of the scalar polarizability $$\alpha$$ to the vector polarizability $$\beta$$ for the $$6s ^2S_{1/2} \rightarrow 7s ^2S_{1/2}$$ transition in atomic cesium. These measurements are motivated by a discrepancy between the values of the vector transition polarizability as determined using two separate methods. In the present measurement, we use a two-pathway, coherent-control technique in which we observe the interference between a two-photon interaction driven by infrared light at 1079 nm and a linear Stark-induced interaction driven by the mutually-coherent second harmonic of this infrared beam at 540 nm. The result of our measurements is $$\alpha/\beta = -9.902 \: (9)$$, in good agreement with the previous determination of this ratio. This measurement, critical to the study of atomic parity violation in cesium, does not reduce the discrepancy between the two methods for the determination of the vector polarizability $$\beta$$ for this transition.
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Retardation effects in atom-wall interactions
The onset of retardation effects in atom-wall interactions is studied. It is shown that the transition range from the $1/z^3$ short-range (van der Waals) interaction to the $1/z^4$ long-range (Casimir) retarded interaction critically depends on the atomic properties and on the dielectric function of the material. For simple non-alkali atoms (e.g., ground-state hydrogen and ground-state helium) interacting with typical dielectric materials such as intrinsic silicon, the transition to the retarded regime is shown to proceed at a distance of about 10 nm (200 Bohr radii). This is much shorter than typical characteristic absorption wavelengths of solids. Larger transition regimes are obtained for atoms with a large static polarizability such as metastable helium. We present a simple estimate, $$z_{crit} = 137 \, \sqrt{\alpha(0)/Z}$$ atomic units, where $$\alpha(0)$$ is the static polarizability (expressed in atomic units) and Z is the number of electrons of the atom.
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- Award ID(s):
- 2149082
- PAR ID:
- 10491382
- Publisher / Repository:
- American Physical Society
- Date Published:
- Journal Name:
- Physical Review A
- Volume:
- 109
- Issue:
- 2
- ISSN:
- 2469-9926
- Page Range / eLocation ID:
- 022808
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1103/PhysRevA.109.022808
