A clock transition for future optical frequency standard with trapped atoms

• Published in: 2003 European Quantum Electronics Conference. EQEC 2003 (IEEE Cat No.03TH8665) p. 265
• Main Authors: Courtillot, I., Quessada, A., Brusch, A., Kolker, A., Kovacich, R.P., Acef, O., Santarelli, G., Clairon, A., Rovera, G.D., Lemonde, P.
• Format: Conference Proceeding
• Language: English
• Published: IEEE 2003
• Subjects: Atom optics; Atomic beams; Atomic measurements; Charge carrier processes; Clocks; Energy measurement; Frequency measurement; Optical saturation; Resonance; Resonant frequency
• ISBN: 9780780377332; 0780377338
• DOI: 10.1109/EQEC.2003.1314122

Direct observation and frequency measurement of /sup 1/S/sub 0//spl rarr//sup 3/P/sub 0 /line within an accuracy of 20 kHz is reported. The resonance frequency with an accuracy of /spl sim/ 100 kHz is reported by indirect measurement of the energy difference between /sup 1/S/sub 0/ and /sup 3/P/sub 0/ states. It is performed by successive frequency measurements of atomic transitions with higher linewidth, easier to observe: /sup 1/S/sub 0/ - /sup 3/P/sub 1/, /sup 3/P/sub 1/ - /sup 3/S/sub 1/ and /sup 3/S/sub 1/ - /sup 3/P/sub 0/ transitions. To perform direct observation of the clock transition, atoms are cooled to a temperature of /spl sim/ 2 mK in a magneto-optical trap (MOT). Although the saturation broadening of the transition is orders of magnitude smaller than the Doppler width (1.5 MHz), a detectable signal is achieved by inducing a small leak in the MOT with a laser tuned to resonance. Atoms accumulate in the metastable /sup 3/P/sub 0 /state where they escape the trap. The resonance is detected by a decrease in the MOT fluorescence signal with a contrast of 1%.