SINGLE Ca~+ ION TRAPPING AND QUADRUPOLE TRANSITION MEASUREMENT TOWARDS AN OPTICAL FREQUENCY STANDARD

摘要

NICT in Japan is developing an optical frequency standard using a quadrupole transition of single Ca~+. After our first measurement, reported at PTTI 2006, we have improved the experimental setup. We have performed laser cooling using two cooling lasers, improved vacuum pressure with an additional getter pump, and introduced a pulse-light sequence to the transition measurement In consequence, we observed the quadrupole transition with a linewidth of ～25 kHz in magnetic fields. The center frequency between the 4 ~2S_(1/2), m_j = -1/2> -3 ~2D_(5/2), m_j=-3/2> and the 4 ~2S_(1/2), m_j=1/2> - 3 ~2D_(5/2), m_j=3/2> components was preliminarily estimated to be 411 042 129 782. 5 ± 1.4 kHz. The measurement will be improved to obtain better uncertainty.