Effects of Polarization Fluctuations in CPT-Based Atomic Clocks

Michael Huang, John Coffer, and James Camparo

Abstract:	In the typical CPT clock, circularly polarized light creates a superposition state between the two mF = 0 ground state sublevels via a common mF = +1 (or mF = -1) excited state. If the laser polarization suddenly changes, the common excited state will also change (e.g., mF = +1 ? mF= -1). This introduces a transient into the CPT signal, which can degrade the clock’s signal-tonoise ratio. Here, we present preliminary results from our experiments examining this issue. In particular, we find that a change in laser polarization leads to a transient change in the CPT signal via two processes. The first appears to be associated with the re-establishment of an equilibrium electronic spin polarization in the vapor, , which, in a four-level model of the CPT signal, can be thought of as a re-establishment of the “trapping state” population; the second process is still under investigation. Each of these processes has a unique timescale, and both will be important for understanding a CPT signal’s response to laser polarization noise.
Published in:	Proceedings of the 39th Annual Precise Time and Time Interval Meeting November 27 - 29, 2007 Hyatt Regency Long Beach Long Beach, California
Pages:	303 - 308
Cite this article:	Huang, Michael, Coffer, John, Camparo, James, "Effects of Polarization Fluctuations in CPT-Based Atomic Clocks," Proceedings of the 39th Annual Precise Time and Time Interval Meeting, Long Beach, California, November 2007, pp. 303-308.
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