Marie Curie Actions: Inspiring Researchers - Imdea

more accurate. Such a clock could be based on countingthe frequency of laser light that is exciting some well-defi nedoptical transition in atoms fl ying in a vacuum – for example,in atomic hydrogen.Going the extra mile for accuracyDr Alnis developed a taste for physics and electronics whilehe was still at school, so his decision to study physics cameas no great surprise. He started out with a Bachelor’s degree,majoring in electronics at the University of Latvia in Riga.However, ‘in electronics, there was not much research at thetime’ in Latvia, he explains. So, as Riga was home to a verysuccessful research group in laser spectroscopy and optics,Dr Alnis decided to change his specialisation.After his doctoral research and several research stays abroad,Dr Alnis asked Professor Theodor Hänsch at the MPQ, whom heremembered from a conference, if he could join the professor’sgroup as a postdoc. Happy to be accepted, he applied forMarie Curie support for the Hydrogen 1S-2S project at theend of his fi rst year.Under the mentorship of Professor Hänsch, who was awardedthe Nobel Prize in physics in 2005, Dr Alnis and his colleaguesdeveloped extremely stable Fabry-Pérot resonators. They ‘consistof two parallel mirrors which are separated by a spacer. Theyare necessary to pre-stabilise lasers for precision experiments,’Dr Alnis explains. An improved resonator design, which is nowbeing implemented by several other groups, helped to create‘some of the world’s most stable diode lasers with sub-Hzspectral line width,’ he notes. ‘We have two such lasers. Forfi ne-tuning, we listen to the amazingly stable difference betweenthese two huge optical frequencies on the loudspeaker – andit’s like music.’Shaping the future of timeDue to its outstanding stability, the diode laser system is of greatinterest to the antimatter spectroscopy group at the EuropeanOrganization for Nuclear Research, CERN, which is pursuinga long-term project to compare optical transition frequenciesin hydrogen and anti-hydrogen. And CERN is not alone in itsinterest in Dr Alnis’ research. Leading metrology institutionsworldwide have sought his cooperation in connection with38