München 2004 – wissenschaftliches Programm
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Q: Quantenoptik und Photonik
Q 40: Laserspektroskopie
Q 40.6: Vortrag
Donnerstag, 25. März 2004, 17:45–18:00, HS 204
Coherent Population Trapping with Variable Doppler Sensitivity — •Christian Bolkart1,2, Danijela Rostahar1,2 und Martin Weitz1,2 — 1Physikalisches Institut — 2Auf der Morgenstelle 14; 72076 Tuebingen
Coherent population trapping is a resonance phenomenon which is of large current interest in the context of slow light, quantum computing and magnetometry. In a three-level system with two stable ground states and one spontaneously decaying upper state driven by two laser fields, atoms can be pumped into a ”dark” coherent superposition of the ground states. This dark state does not interact anymore with the laser field.
We have studied dark resonances in a thermal gas of rubidium atoms using a variable angle between the two driving optical beams. The angle was tuned between a Doppler-free situation (zero angle) and angle near 10(−3) radians, the latter corresponding to the Doppler-sensitivity of a far infrared photon. We find that the amplitude of the dark resonance is close to the Doppler-free case as long as the Doppler-effect does not contribute significantly to the linewidth, but decreases rapidly for larger angles. We have furthermore recorded similar spectra using rubidium cells with neon buffer gas, which allows us to investigate the Dicke-effect in a new regime.