ERC Starting Grant - Helium dimer Ultracold Molecules.

Helium dimer Ultracold Molecules - a platform for fundamental physics and ultracold chemistry

Molecules at standstill

To reach high precision in spectroscopic measurements, we would like to trap our molecules. This is necessary, because when molecules move around, they experience the laser radiation used in the measurements differently. That’s the Doppler effect, which is also known in everyday life: it causes an ambulance siren to sound higher in pitch when it is approaching than when it is receding. Having the molecules at one location makes it also easier to determine and compensate interactions with the environment, which might otherwise distort the measurements. While trapping is relatively easy for molecular ions (we use radio-frequency traps for our measurements on H$_2^+$), it is much more complicated for neutral molecules.

Laser cooling

Within this ERC Starting Grant we want to laser cool the simplest neutral molecule possible. And as it turns out, this is not molecular hydrogen, but molecular helium. He$_2$ is the simplest molecule for which laser cooling to near absolute zero temperature seems feasible - which is the main goal of this project. At near zero temperature, the molecules hardly move due to the vanishing kinetic energy and therefore allow very precise measurements.

Platform for fundamental physics and chemistry research

If successful, this will deliver the fifth-ever molecule that was directly laser-cooled and trapped. Compared to all other molecules laser cooled to this day, the simplicity of He$_2$ makes very accurate calculations of its collision properties possible. This will allow to study ultracold collisions and chemical reactions with unprecedented accuracy. Being able to understand and control the collision properties is crucial for producing a molecular Bose-Einstein condensate. With such a system, applications range from testing quantum electrodynamics to quantum information and many-body physics.

Open PhD and postdoc positions. Please contact m.beyer@vu.nl