# Previous Michelson Postdoctoral Prize Lectureships

## Tuesday, May 11, 2010 , 11:30 a.m. in Miller Room

David Hanneke, NIST

#### Optical Atomic Clocks

The most precise measurement techniques involve time, frequency, or a
frequency ratio. For example, for centuries, accurate navigation has relied
on precise timekeeping -- a trend that continues with today's global
positioning system. After briefly reviewing the current microwave frequency
standards based on the hyperfine structure of cesium, I will describe work
towards atomic clocks working at optical frequencies. Among these are
standards based on trapped ions or on neutral atoms trapped in an optical
lattice. A frequency comb allows the comparison of different optical
frequencies and the linking of optical frequencies to more-easily-counted
microwave ones. Though still in the basic research stage, optical clocks
have already made significant contributions to physics by setting limits for
time-variation of the fundamental constants, seeing general relativistic
effects at the centimeter scale, and testing local position invariance by
looking for differential redshifts as the Earth moves in the Sun's
gravitational potential.

Download David's Slides for this talk.

Download David's Slides for this talk.

Host: Harsh Mathur