Photon-Trap Spectroscopy

Jens Lykke Sørensen, Jan Hald, Eugene Simon Polzik

We demonstrate a new type of high-resolution two-photon frequency modulation (FM) spectroscopy with cold atoms in a magneto-optical trap. Instead of modulating the probe as in ordinary FM spectroscopy, we modulate the trap itself by FM of the trapping beams. We present theoretical as well as experimental results for both absorption and polarization rotation spectroscopy. Finally, we demonstrate two-photon FM spectroscopy, using the intrinsic phase noise of the trapping diode lasers.

E. G. Varona

P. Bräunlich

Akira Terasaki, T. Majima, Tamotsu Kondow

A novel experimental technique has been developed to observe a trace of optical absorption of free mass-selected ions. The technique combines a linear radio-frequency ion trap with a high-finesse optical cavity to perform cavity ring-down spectroscopy (photon-trap spectroscopy for generality), where the storage lifetime of photons in the cavity provides a sensitivity high enough to probe the trapped ions. Absorption spectra of the manganese ion Mn(+) are presented, showing hyperfine structures for the (7)P(2,3,4)<--(7)S(3) transitions in the ultraviolet range. Implementation of a solenoidal magnet allows us to observe the Zeeman splitting and the Faraday rotation as well.

Claudio Lenz Cesar, Daniel Kleppner

We describe the systematics of two-photon Doppler-free excitation of atoms confined in a cylindrical harmonic trap, at densities far from the regime of quantum degeneracy. The line shape is explained in terms of momentum transfer between the light beam and the trapped atoms. This formalism extends the semiclassical analysis of time-of-flight broadening. The results, which are general, were motivated by the development of two-photon Doppler-free spectroscopy of trapped atomic hydrogen.

Bernard Cagnac