Conference talk Jeroen Koelemeij

Speaker: 
Jeroen Koelemeij
Affiliation: 
VU University
Title: 
Accurate clocks based on atoms and molecules: what is hiding behind the next decimal?
Abstract: 

Today’s most accurate clocks are based on optical transitions in atoms, excited by ultrastable lasers with a linewidth below 1 Hz. Exploiting advanced laser cooling and manipulation methods and long storage times in atom traps, frequency uncertainties well below one part in 10^17 have been achieved. In the wake of this development, optical clocks based on vibrating molecules are now being set up, including simple and therefore highly ‘calculable’ species such as the molecular hydrogen ion H2+. While atomic and molecular optical clocks are very similar in design and operation, they represent fundamentally different oscillators with clock frequencies depending on the fine-structure constant for atoms, and on the proton-electron mass ratio for molecules. Clock comparisons thus enable various stringent tests of fundamental laws of physics, as well as searches for possible ‘new physics’ hiding behind the next digit of precision. Furthermore, the need to compare optical clocks operated by different laboratories – often separated by distances of hundreds of kilometers – has spurred the development of time and frequency transfer methods through fiber-optical links in public telecommunication networks. It has recently been suggested that this technology may soon provide the next digits of precision for time distribution as well as positioning, offering a performance beyond that of the Global Positioning System.

Date: 
Friday, April 17, 2015 - 16:00 - 17:00