Bon MOT: Innovative atom trap catches highly magn...( A research team from the National In...)

A research team from the National Institute of Standards and Technology (NIST) and the University of Maryland has succeeded in cooling atoms of a rare-earth element, erbium, to within two millionths of a degree of absolute zero using a novel trapping and laser cooling technique. Their recent report* is a major step towards a capability to capture, cool and manipulate individual atoms of erbium, an element with unique optical properties that promises highly sensitive nanoscale force or magnetic sensors, as well as single-photon sources and amplifiers at telecommunications wavelengths. It also may have applications in quantum computing devices.

The strongly counterintuitive technique of laser cooling to slow down atoms to very low speedstemperatures close to absolute zerohas become a platform technology of atomic physics. Laser cooling combined with specially arranged magnetic fieldsa so-called magneto-optical trap (MOT)has enabled the creation of Bose-Einstein condensates, the capture of neutral atoms for experiments in quantum computing and ultra-precise time-keeping and spectroscopy experiments. The technique originally focused on atoms that were only weakly magnetic and had relatively simple energy structures that could be exploited for cooling, but two years ago a NIST team showed that the far more complex energy structures of erbium, a strongly magnetic element, also could be manipulated for laser cooling.

The typical MOT uses a combination of six tuned laser beams converging on a point that is in a low magnetic field but surrounded by stronger fields. Originally, the lasers were tuned near a strong natural energy oscillation or resonance in the atom, a condition that provides efficient cooling but to only moderately low temperatures. In the new work, the research team instead used much gentler forces applied through a very weak resonance in order to bring erbium atoms to within a few millionths of a degree of absolute zero. Such wea
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