A method for controlling the spins of atoms using optical near-fields

HARUHIKO ITO

治彦 伊藤, HARUHIKO ITO

Yasuo Ohdaira, K. Kijima, K. Terasawa +3 more

Spin-sensitive optical near-field microscopy and spectroscopy are proposed based on the study on the conserved quantities in optical near-field interactions of atoms with dielectric surfaces. A two-step photoionization spectra of Cs atoms resolving hyperfine structures are demonstrated near a planar dielectric surface by using evanescent waves. These techniques of state/spin-selective excitation and highly sensitive detection, combined with the techniques of optical pumping, will open up possibilities of space- and polarization-sensitive detection of optical near-fields using atomic probes. This novel method provides us with a useful technique for the observation of polarization nature of the optical near-field and controlling the spin states of mesoscopic electronic systems.

Akira Shojiguchi, Kazuo Kitahara, Kiyoshi Kobayashi +1 more

On the basis of the procedure for controlling the spins of atoms using circularly polarized evanescent light proposed by Hori et al.[(1996) Abstracts of the 1st Asia-Pacific Workshop on Near-field Optics] we discuss the influence of boundary conditions on the probability of spontaneous emission and thus on the spin polarization efficiency, which was not considered in the Hori et al. study. Using the Carniglia-Mandel mode expansion of electromagnetic fields, we derive the spontaneous emission and spin polarization probabilities of atoms near a dielectric surface, and show the atom-surface distance dependence and refractive index dependence. Numerical evaluation for the 6P1/2-6S1/2 transition of a Cs atom indicates an increase in the efficiency of spin polarization by 30%.

Haruhiko Ito, Motoichi Ohtsu

Optical near field realizes the precise control of atomic motion .As the first step, guiding of atoms through micron-sized hollow optical fiber is demonstrated .The two-step laser-photoionization spectroscopy shows the frequency dispersion properties of dipole interaction between atoms and optical near field .The species-and state-selective guidance is applied to in-line spatial separation of two stable Rb isotopes .In addition, the cavity QED (Quantum Electrodynamics) effect inside a dielectric cylinder is observed for the first time.The atom fiber has the faculty of carrying atoms to an arbitrary point over a long distance and then is useful as a novel scheme of optically controlled atomic deposition.The feasibility of creating dot-shaped nano-scale structures is illustrated through measurement of spatial distribution of the guided atom flux .Finally, a method of manipulating atoms beyond the diffraction limit of light waves is presented including sharpened optical fibers and an atomic funnel with optical near field.

U. Janicke, Martin Wilkens