Berlin 2001 – wissenschaftliches Programm
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A: Atomphysik
A 17: Posters Friday (Spectroscopy)
A 17.18: Poster
Freitag, 6. April 2001, 12:30–15:00, AT3
Coherent spectroscopy of degenerate two-level systems in Cs — •Christina Andreeva1, Valerio Biancalana2, Alessia Bruchianti2, Stefka Cartaleva1, Yordanka Dancheva1, Carmen Marinelli2, Emilio Mariotti2, and Luigi Moi2 — 1Institute of Electronics, Bulgarian Academy of Sciences, Boul. Tsarigradsko Shosse 72, Sofia 1784, Bulgaria — 2Dipartimento di Fisica, Universita di Siena, Via Banchi di Sotto 55, 53100 Siena, Italy
Experimental examination of the coherent population trapping (CPT) that can be established on the D2 line of Cs at single hyperfine transition using the Zeeman sublevels of the hyperfine states is reported. Exciting Cs vapour in a glass cell by monomode laser beam, subnatural width dips and peaks in the fluorescence in dependence on magnetic field, centered at zero magnetic field, are observed. In case of degeneracy of the ground level Fg lower than that of the excited level Fe, narrow bright peak in the fluorescence occurs, while for Fg higher then or equal to Fe dark resonance is observed. The parameters of the resonances are investigated in dependence on the power and polarization of the laser beam, and on the buffer gas pressure in the cell. At laser power densities of 0.05 mW/cm2 dark resonances of 8 kHz FWHM were observed, which is orders of magnitude less than the natural width of the transition (4.5 MHz). It is proposed to utilize the CPT structure for measurement of very weak magnetic fields.