A National Institute of Standards and Technology (NIST) group can now supply chromium atoms on demand, one at a time. This is the first time such control over neutral atom delivery has been achieved. At the microscopic level, delivering electrons in a circuit or photons from a laser or atoms from a trap one at a time is more difficult than one would think.
Precision control over motion is tricky enough, but getting the objects to come one at a time, and not in twos, threes, or larger groups, is even harder.
Jabez McClelland and his colleagues send a tenuous beam of Cr atoms toward a magneto-optic trap. The atoms, which can be put into various excited states with a laser beam, announce their presence and their number by the photons they emit.
If just one atom has come along, its emissions can be used to trigger a gate turning the loading of the trap on or off. In this way a single atom can be trapped by design, and at a rate of many atoms per second.
Extracting the atoms controllably, with gravity or with "optical tweezers," will be the final step in obtaining mastery over the single atoms.
A deterministic source of single atoms is expected to be a critical component of various integrated atom-optic (atomtronics) schemes. Why chromium atoms? Because Cr atoms have a magnetic moment 6 times larger than alkali atoms, making the trapping process much easier.
The NIST group will report its finding at an upcoming APS meeting (Division of Atomic, Molecular, and Optical Physics, DAMOP) in Williamsburg, Virginia May 28-June 1.
(Editor's Note: This story is based on one in PHYSICS NEWS UPDATE, the American Institute of Physics Bulletin of Physics News Number 589, May 15, 2002, by Phillip F. Schewe, Ben Stein, and James Riordon.)
[Contact: Jabez McClelland]
17-May-2002
