Colloquium – Jeffery Sherman – Atomic timekeeping

Speaker: Dr. Jeffery Sherman (NIST)

Title: Atomic timekeeping

Abstract:

At present, our best recipe for measurement of time calls for keeping a continuous count of a stable, periodic process, such as oscillations of an isolated naturally-occurring quantum mechanical system. Atomic clocks and frequency references underpin essential technologies like global positioning, telecommunications, and effectively all dimensional metrology. Atomic clocks enable a wide array of scientific studies, including very-long baseline interferometry and fundamental tests of physics. New atomic frequency references based on optical transitions are comparable with an uncertainty below that of practical realizations of the SI second, a source of tension which now motivates a campaign to redefine the SI second. Challenges remain, including demonstrating that such optical standards are widely realizable internationally with the promised two orders of magnitude of accuracy improvement—watching the clock all day for the U.S. government has never been more exciting!

Bio:

Jeff Sherman currently leads the Time Realization and Distribution Group at the National Institute of Standards and Technology. The group works to maintain and improve NIST systems that produce and distribute official U.S. time, time-interval, and frequency signals, which are based on an ensemble of atomic clocks and frequency references. Jeff’s research has centered around high-precision measurements in optical-atomic systems and includes a Ph.D. in Physics from the University of Washington (2007), postdoctoral work at the University of Oxford, and a National Research Council research associateship at NIST.

Host: Thejesh N. Bandi