University of ​Copenhagen 

The Quantum Metrology group at the Niels Bohr Institute, University of Copenhagen, does research primarily within cold atom physics and optical frequency references. The group has more than 17 years of experience working with cold two-electron atoms, such as Mg and Sr, for precision measurements and was the first to realize a BEC in Denmark using Na. Recently, the group demonstrated the potential of combining a low finesse optical cavity and atoms with narrow linewidth for bringing down local oscillator frequency noise and instability. 

Within iqClock the Copenhagen group will collaborate with the Amsterdam, Vienna and Innsbruck groups to build a continuously operating superradiant clock on the kHz transition of strontium (Task 2).

Group webpage

Team members

Jan W. Thomsen received his Ph.D. in Paris and is leading the Copenhagen initiative on merging cavity QED and optical clock technology to improve further the local oscillator stability and precision. In connection to this project there are strong collaborations with Danish Fundamental Metrology (DFM), the Danish Measurement Institute, Dr. Jan Hald and with leading international atomic clock teams headed by Prof. Jun Ye and Prof. James K. Thompson at JILA (University of Colorado). JWT spends 1-2 months a year at JILA working primarily in the group of Prof. Jun Ye with  87 Sr optical lattice clocks. JWT spent 2007-2008 as a JILA visiting fellow.

Contact: [email protected]

Stefan Alaric Schäffer, PhD fellow
Stefan works on the cold strontium experiment where he has demonstrated the potential for using narrow linewidth atoms in low finesse cavities as frequency references. The same testbeds developed from these approaches will be used to demonstrate active clock operation on the kHz line of Strontium-88.
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Contact: [email protected]

Mikkel Tang, PhD fellow
Mikkel works on the Strontium 3D MOT experiment and the next generation of active clock experiments based on the kHz line. During his master's thesis he worked on simulations and experiments with pumping and active lasing in the 3D MOT system.

Contact: [email protected]