Scientists drive atom lasers forward

17 Jun 2002

Researchers have developed an optical-based system that manipulates and focuses atom lasers.

Microscopy

A breakthrough from scientists at Germany's Ludwig Maximilians Universität and the Max-Planck Institute of Quantum Optics is set to revolutionize the field of atomic optics. Tilman Esslinger and colleagues have developed a novel atom optical element that manipulates an atom laser. The scientists' work could pave the way to better atomic clocks and a new wave of atom microscopes.

The researchers magnetically trapped a cloud of rubidium atoms in a Bose-Einstein condensate and then breached the trap to release a coherent laser beam of atoms. By using a combination of laser and magnetic fields, which formed the basis of the atom optical element, the researchers reflected, stored and focused the atom laser.

"The actual force exerted on the atom laser beam is due to a magnetic-field gradient," explained Esslinger. "The trick is to switch the force on and off using the laser fields."

The researchers used the magnetic field as a mirror to reflect the laser beam and store it in a magnetic trap, or resonator. While inside the resonator, the beam oscillated backwards and forwards and after just 18 ms, narrowed by 25%. Esslinger believes that by focusing the laser in this way, his team has made the first key step toward an atom-laser microscope. Such a microscope would be less damaging to a sample than the electron counterpart.

"The simplest type of atom-laser microscope would be a transmission microscope," he said. "Scanning a sample through the focus of the laser beam would give an image of the structure."

Esslinger would also like to focus the atom laser beam to smaller spot sizes. "A focus of 100 nm does not seem unrealistic to me, "he said. "In principle even smaller foci should be possible."