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Q: Quantenoptik
Q 9: Poster: Quantum Information
Q 9.18: Poster
Tuesday, April 3, 2001, 12:30–15:00, AT2
Lifetime measurement as a test of cooperative effects in ion strings — •M. Block, A. Drakoudis, H. Garcia-Prima, H. Leuthner, X. Luo, and G. Werth — Institut für Physik der Johannes Gutenberg Universität, Staudingerweg 7, 55099 Mainz
We have measured the lifetime of the metastable 3D5/2 level in 40Ca+. The effective lifetime represents an upper limit for the coherence time in proposed quantum computation schemes using linear chains of ions [1]. We used the method of quantum jumps of a single trapped ion and obtained 1100(18)ms [2] as the lifetime. In a second stage we performed measurements on strings of ten ions which were observed individually by a CCD camera. In some of the runs we found a substantially reduced lifetime compared to the single ion value under nominally identical conditions. In these cases we observed more frequently coincident decays of two or more ions than one expects for statistically independent particles within the time window given by our detection system. Since the distance of the ions is large compared to the wavelength (about 10λ) superradiance is excluded. Similar observations have been made in 1986 [3] for few ions but recently a similar experiment at Oxford did not show enhanced coincidences for two and three ions [4]. We are currently performing further experiments to confirm our observation and to search for an explanation.
[1] Cirac, Zoller, PRL 74,4091 (1995)
[2] Block et al., EPJD 7,461 (1999)
[3] Sauter et al. Opt. Commun. 60, 287 (1986)
[4] Donald et al. Europhys. Lett. 51, 388 (2000)