Title :
Does the light shift drive frequency aging in the rubidium atomic clock?
Author_Institution :
Electron. & Photonics Lab., Aerosp. Corp., Los Angeles, CA, USA
fDate :
7/1/2005 12:00:00 AM
Abstract :
Frequency aging in the rubidium (Rb) vapor-cell atomic clock plays a significant role in the device´s timekeeping ability. Though many researchers have speculated on the physical mechanism(s) driving the linear, deterministic frequency change (i.e., /spl Delta/f(t)/f/sub o/ = At), there is little unambiguous experimental data regarding the phenomenon. Here, long-term data were used from on-orbit global positioning system (GPS) Rb clocks to examine one postulated mechanism for frequency aging (i.e., the light-shift effect). Defining the light shift of the clock´s fractional frequency as /spl alpha/I/I/sub o/, where /spl alpha/ is the light-shift coefficient, we find that temporal variations of the relative light intensity, I/I/sub o/ cannot account for frequency aging. However, for the population of clocks considered here, we obtain the intriguing result that /spl lambda//A = 1.7 /spl plusmn/ 1.5. Thus, it may be that frequency aging is driven by the light-shift effect through temporal variations of the light-shift coefficient.
Keywords :
Global Positioning System; atomic clocks; fluctuations; frequency stability; frequency standards; rubidium; stochastic processes; Rb; atomic clock; atomic standards; clock fractional frequency; frequency aging; frequency stability; light shift; light-shift coefficient; on-orbit global positioning system; rubidium clock; rubidium vapor-cell; stochastic frequency fluctuations; Aging; Atomic beams; Atomic clocks; Frequency synchronization; Global Positioning System; Laboratories; Resonance; Root mean square; Stability; Stationary state;
Journal_Title :
Ultrasonics, Ferroelectrics, and Frequency Control, IEEE Transactions on
DOI :
10.1109/TUFFC.2005.1503993