D A Howe
University of Colorado, USA
Title: Phase stability in next-generation atomic frequency standards
Biography
Biography: D A Howe
Abstract
Atomic clocks (or oscillators) form the basis of standard, everyday timekeeping. Separated, hi-accuracy clocks can maintain nanosecond-level autonomous synchronization for many days. The world’s best Cs time standards are atomic fountains that use convenient RF quantum transition at 9,192,631,770 Hz and reach total frequency uncertainties of 2.7 – 4×10-16 with many days of averaging time. A new class of optical atomic standards with quantum transitions having +1×10-15 uncertainty drives an optical frequency-comb divider (OFD), thus providing exceptional phase stability, or ultra-low phase noise (ULPN), at convenient RF frequencies. In terms of time, this means that a 1 ns time difference wouldn’t occur in a network of clocks for 15 days. I show how the combination of high atomic accuracy and low-phase noise coupled with reduced size, weight, and power usage pushes certain limits of physics to unlock a new paradigm – creating networks of separated oscillators that maintain extended phase coherence, or a virtual lock, with no means of synchronization whatsoever except at the start. This single property elevates their usage to a vast array of applications that extend far beyond everyday timekeeping. I show how accurate oscillators with low-phase noise dramatically improves: position, navigation, and timing; high-speed communications, private messaging and cryptology, and spectrum sharing. This talk outlines game-changing possibilities in these four areas to the degree that clock properties are sustained in application environments. I will show a summary of several ongoing US programs in which the commercial availability of such low-phase noise, atomic oscillators are now a real possibility.