A light beam is usually divided by being directed onto a partially reflecting mirror: Part of the light is then reflected back to create the mirror image. The rest passes through the mirror. "However, this process can be turned around if the experimental set-up is reversed," says Prof. Dr. Martin Weitz from the Institute of Applied Physics at the University of Bonn. If the reflected light and the part of the light passing through the mirror are sent in the opposite direction, the original light beam can be reconstructed.
The physicist investigates exotic optical quantum states of light. Together with his team and Prof. Dr. Achim Rosch from the Institute for Theoretical Physics at the University of Cologne, Weitz was looking for a new method to generate optical one-way streets by cooling the light particles (photons): As a result of the smaller energy of the photons, the light should collect in various valleys and thereby be irreversibly divided. The physicists used a Bose-Einstein condensate made of photons for this purpose, with which Weitz made a name for himself in 2010 because he was the first to create such a "super-photon."
Beam - Light - Forth - Mirrors - Process
A beam of light is thrown back and forth between two mirrors. During this process, the photons collide with dye molecules located between the reflecting surfaces. The dye molecules "swallow" the photons and then spit them out again. "The photons acquire the temperature of the dye solution," says Weitz. "In the course of this, they cool down to room temperature without getting lost."
By irradiating the dye solution with a laser, the physicists increase the number of photons between the mirrors. The strong concentration of...
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