Molecule interferometry

The motivation for de Broglie interference of heavy particles is manifold, for example, to address the foundations of physics by invesitgating the quantum to classical transition, the use of interferometric techniques for applications as for example: molecule metrology, molecule sorting, molecule quantum interference lithography and investigations of van der Walls/Casimir-Polder interactions, and to study the coherent manipulation of complex partciles for instants  to reconstruct the Wigner function of the motional quantum state of the diffracted molecules.  The centre-of-mass interferometry is not affected by internal excitation of the molecules as impressively demonstrated by our experiments. If however internal state dynamics is coupled to the centre-of-mass motion by electric or optical fields, the interference pattern is changed. I will explain our experiment on mapping the dynamics of the change of conformation of hot molecules onto its centre of mass motion while measuring the interference pattern. I will further emphasise the status of the develpoment of the Southampton molecule interferometer, where we recently achieved 27% of quantum contrast.
	
Manipulation and cooling the motion of complex partciles to increase beam coherences and beam brightness as well as decreacing speeds is essential for interference experiments. Therefore we are interested in optical techniques to mechanically effect the motion of molecules. I will report on our recent experimental results on lensing a fulleren beam by a focused beam of a ultrashort-pulsed laser. These results are confimed by Monte-Carlo simulations as well as by adjusting an analytical model to the experimental parameter. We think that these experiments represent an important step to study this kind of light-matter interaction towards optical cooling the motion of complex molecules.  

In the last part I will illustrate our ideas for de Broglie interference of polystyrene or glass spheres (beads) of up to 100nm diameter. Our approach considers the use of optical near-field enhanced trapping of those particles close to nano/micro-structured thin metal films (self-induced back action effect) as a launch pad for Talbot-Lau interferometry. We have very recently started the first experiments.