Stefan Truppe receives ERC Starting Grant to study cold molecules

Each year, the European Research Council awards Starting Grants to early-career scientists who have excellent academic track records and are ready to lead a large research project independently. For Dr. Stefan Truppe, who has been a group leader in the Department of Molecular Physics since 2017, this Grant comes at just the right time. Over the last three years, together with his team, he laid a lot of the groundwork needed for this research. With this Grant, they can reach the next milestone – the creation of a quantum gas of polar molecules, a long-standing goal of the atomic, molecular and optics community sometimes described as the ‘holy grail’ of experimental molecular physics.

The aim of his project, titled “Cold Molecules for Fundamental Physics” (with the jolly acronym CoMoFun), is to cool a molecular gas to ultra-low temperatures - only a millionth of a degree above absolute zero. “The reason for doing this is pretty simple”, explains Dr. Truppe, “thermal energy makes molecules move fast and in random directions and patterns. But when they are cold, molecules are significantly slower, so in order to study them at high levels of precision, we need to cool them, slow them down and catch them in a trap. It‘s like catching a microscopic chicken.”

Studying these molecules in this way also opens a lot of other doors. At ultra-low temperatures the molecules enter the so-called ‘quantum regime’, meaning that they stop behaving according to the laws described by classical physics. They can thus be used to study new quantum effects and to build universal quantum simulators. With the cooled and isolated molecules you can ‘build’ a model-system of complex materials and study their behavior in a very controlled environment. “That is one of the most exciting aspects of this research”, Dr. Truppe comments, “as this is simply impossible to model, even with a supercomputer.” Such simulations from the bottom-up will aid the understanding of fascinating phenomena such as high-temperature superconductivity and exotic forms of magnetism.

A plethora of new, exciting applications await once the molecules are cold enough to be trapped and manipulated. The research field to cool molecules is motivated also by the success story of laser-cooled, ultracold atomic gases. The study of those atomic gases has revolutionized modern physics. It deepened our understanding of fundamental physics and has had a profound impact on modern, 20^th-century technology. For example, ultra-precise atomic clocks, based on laser-cooled atoms, are now the backbone of modern GPS. The study of ultra-cold molecules will likely have a similar impact on fundamental science and technology.

Dr. Stefan Truppe studied Physics at the University of Vienna, Austria, and gained his PhD at Imperial College London, United Kingdom. He then accepted a PostDoc position at Imperial College before coming to the Fritz Haber Institute in 2017.