title: Improved short-term stability of optical frequency standards: approaching 1 Hz in 1 s with the Ca standard at 657 nm.
abstract: For a neutral (40)Ca-based optical frequency standard we report a fractional frequency instability of 4 x 10(-15) in 1 s, which represents a fivefold improvement over existing atomic frequency standards. Using the technique of optical Bordé-Ramsey spectroscopy with a sample of 10(7) trapped atoms, we have resolved linewidths as narrow as 200 Hz (FWHM). With colder atoms this system could potentially achieve an instability as low as 2 x 10(-16) in 1 s. Such low instabilities are important for frequency standards and precision tests of fundamental physics.
authors: Time and Frequency Division, National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80303, USA.
authors: C W
authors: CW
authors: Oates
authors: E A
authors: EA
authors: Curtis
authors: L
authors: L
authors: Hollberg