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 toward the 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 speeds—temperatures close to absolute zero—has become a platform technology of atomic physics. Laser cooling combined with specially arranged magnetic fields—a so-called magnetooptical trap (MOT)—has enabled the creation of Bose-Einstein condensates, the capture of neutral atoms for experiments in quantum computing and ultra-precise timekeeping 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; however, 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.
Color-enhanced image of a cloud of erbium atoms trapped and cooled, and a narrow-line MOT using a single laser beam. The laser beam is coming down from the top of the image, which measures about 1 millimeter square. The atoms collect along the ellipse of a constant magnetic field (dashed line) where they come into resonance with the laser. (Click image to enlarge)
