Quenched narrow-line second- and third-stage laser cooling of ^40 Ca

We demonstrate three-dimensional 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 (which is quenched by an intercombination line at 552 nm), thereby reducing the atoms’ temperature from 2 mK to 10 μK. This reduction in temperature should help to reduce the overall systematic frequency uncertainty for our Ca optical frequency standard to <1 Hz. Additional pulsed, quenched, narrow-line third-stage cooling in one dimension yields subrecoil temperatures as low as 300 nK and makes possible the observation of high-contrast two-pulse Ramsey spectroscopic line shapes.