A team of researchers from the University of Southampton have successfully used matter waves to cool molecules that cannot be handled by typical laser methods. This is the first demonstration of this technique, which was first proposed by Martin Weitz and Ted Hänsch in 2000. The team’s research has been published in the Physical Review Letters and is titled “Interferometric Laser Cooling of Atomic Rubidium.”
Cold atoms are frequently used in atomic clocks, physics research, and possibly in quantum computers.
“Currently, atoms are cooled from room temperature to near absolute zero by preferential scattering of laser photons from the moving particle, which slows it. This requires a favorable electronic structure and is limited to a small fraction of atomic elements and a few diatomic molecules,” the team reported.
“There is a great push to extend ultra-cold physics to the rest of the periodic table to explore a wealth of fundamental processes and develop new technologies. Our technique, should we succeed in extending it to Weitz and Hänsch’s complete scheme, would be sort of a catch-all, that’s why this is exciting, even though our actual experiment just uses atoms,” Dr. Alex Dunning, Southampton physicist, said.
During the demonstration, the team used a Rubidium that was already cold and lowered its temperature down close to the limit of laser cooling.
“The same atom is both the matter waves, as it is placed into a superposition of states by a laser pulse and travels simultaneously along two paths, which interfere at a later time. Impulse imparted to the atom depends on how the difference in energy along the two paths compares with the energy of the laser photons, where the atom’s energy is formed of potential (internal electron configuration) and kinetic (external motion) parts,” according to the university.
“The clever trick behind Weitz and Hänsch’s scheme is to make the laser interact with the atoms in such a manner as to remove the dependence on the potential energy, and thus the internal electronic structure, leaving the interference based solely on the kinetic energy of the particle,” researchers added.
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