Experimental overview

Warning: sizeof(): Parameter must be an array or an object that implements Countable in /home/Grupos/quantumnano/public_html/wp-content/plugins/papercite/papercite.php on line 205

Overview of the
Kapitza-Dirac-Talbot-Lau Interferometer

The Kapitza-Dirac-Talbot-Lau interferometer has been in operation since 2006 and is continuously remodelled. It consists of a source, the interferometer and a detector. In order to avoid any influence from external factors it is built into a vacuum chamber that is mounted on a vibration isolated optical table.

While we can describe the molecules in the source and in the detector by classical physics, inside the interferometer we want to analyze phenomena that can only be described by the physics of quantum mechanical matter waves.


The molecules (pink beam) exit the source, a small oven for molecules, through a nozzle. The beam can be delimited by the source opening (S1) and two slits (S2, S3). In the interferometer, they pass through three consecutive gratings (G1, LG, G3). The first grating widens the molecular wave function and generates a spatially coherent molecular beam. At the second grating (LG), a standing laser light wave, the molecules get diffracted according to the Kapitza Dirac effect. Quantum interference generates a self image of the diffractive structure (Talbot-Lau effect) at the position of the third grating (G3). This grating can scan the interference pattern as a mask. A mass spectrometer detects the molecules that pass the third grating. In order to measure the velocity of the molecules a chopper wheel can be moved into the beam.

Experimental order

Test your knowledge!

Experimental challenge: First impression

Go to the laboratory and follow the instructions. Once you have accomplished your task, continue here.