Physics Colloquium - Andrew Ludlow, Ph.D.
Monday, November 9, 2009, 04:00 PM
Engineering Building, Room 120 (Hammond Auditorium)

"Timekeeping for Tomorrow: Atomic Clocks Using Ultracold Atoms in an Optical Lattice"

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The colloquium speaker is Andrew Ludlow, Ph.D. Refreshments will be available before the colloquium at 3:45 pm.

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Abstract

Atomic clocks find significant roles in a number of scientific and technological settings. One interesting approach to a next-generation clock utilizes alkaline earth atoms confined in an optical lattice. Strong confinement of the atoms eliminates motional effects which otherwise trouble the interrogation of the electronic transition at the heart of the clock.

At the same time, the optical lattice equally perturbs the two electronic clock states so that the confinement introduces a net zero shift of the natural transition frequency. Here I describe the design and realization of optical frequency standards using 87Sr and 171Yb, among the most common choices worldwide for the development of these types of standards.

With an ultra-stable laser light source, atomic spectral linewidths of the optical clock transition are observed below 2 Hz. High accuracy spectroscopy of the clock transition is carried out utilizing a frequency comb referenced to the NIST-F1 Cs fountain clock.

Remote comparison of the Sr system at JILA and the Yb system at NIST enables frequency measurements at a fractional level below 1 part in 1016. The performance of these state-of-the-art systems is discussed, as well as how these systems will improve in the upcoming years.

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About the speaker

Andrew received a B.S. in Physics from Brigham Young University. There he worked with Prof. Scott Bergeson, using optical cavities and laser thermometry techniques to study two photon absorption processes in crystals.

In 2002, he began graduate studies at the University of Colorado in Boulder as part of the Optical Science and Engineering Graduate Fellowship Program. He worked with Prof. Jun Ye, developing an optical atomic clock based on ultracold neutral strontium atoms confined in an optical lattice. This work culminated in an accuracy evaluation of the newly constructed strontium optical frequency standard, demonstrating one of the smallest frequency uncertainties of any standard, including primary standards based on cesium.

Furthermore, these efforts contributed to the international acceptance of the strontium standard as a practical realization of the meter and a secondary representation of the (SI) second. Andrew received the JILA scientific achievement award in 2006 and the 2009 APS DAMOP thesis prize. He currently serves as a National Research Council postdoctoral fellow at NIST in Boulder.

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Event Contact: Kathy Reischauer can be reached at (970) 491-6206

Sponsored by the Physics Department.