  We demonstrate three-dimensional (3-D) quenched narrow-line laser cooling and
trapping of 40Ca. With 5 ms of cooling time we can transfer 28 % of the atoms
from a magneto-optic trap based on the strong 423 nm cooling line to a trap
based on the narrow 657 nm clock transition (that is quenched by an
intercombination line at 552 nm), thereby reducing the atoms' temperature from
2 millikelvin to 10 microkelvin. This reduction in temperature should help
reduce the overall systematic frequency uncertainty for our Ca optical
frequency standard to < 1 Hz. Additional pulsed, quenched narrow-line
third-stage cooling in 1-D yields sub-recoil temperatures as low as 300 nK, and
makes possible the observation of high-contrast two-pulse Ramsey spectroscopic
lineshapes.
