This is a stunning new demonstration of the wavelike behavior of atoms and provides an important tool for eventual technological applications of BECs.

First observed on the surface of a narrow canal in 1834, a soliton is a group of waves combining in such a way as to form a single composite wave that can travel for long distances without spreading out or losing its original shape.

Solitons can occur in all kinds of waves; for example, they have been thoroughly studied in sound waves and light waves. In fact, soliton light waves are currently employed in telecommunications. Solitons can exist in BECs too.

Since a BEC consists of ultracold atoms all in the same quantum state, it exhibits wavelike behavior and therefore can be considered as a single atom wave. However, the BEC atom wave usually spreads apart or "disperses" shortly after the BEC is released from a trap.

Nonetheless, in previous BEC experiments (such as Burger et al., Phys. Rev. Lett., 20 December 1999), researchers have observed "dark solitons," representing absences of atoms that can propagate without changing shape in a condensate.

Now, in a BEC of lithium atoms, the Rice team has produced "bright" solitons, each representing a condensate of actual atoms extracted from the main BEC. In effect, the bright solitons are individual atom waves broken off from the main BEC atom wave.

Using a narrow laser beam to guide BEC atoms in a single-file line, the Rice team tailored the interactions between lithium atoms to be attractive so that the atoms' attraction for one another perfectly offset their predisposition to spread out.

With their technique, the Rice researchers have created "trains" of up to 15 solitons (see figure at this URL).

These atom-wave solitons will likely be a useful tool someday for BEC versions of gyroscopes for ultra-precise navigation and very accurate atomic clocks (Strecker et al., Nature, 9 May 2002 print issue; this work will also be presented in papers G1.011 and R1.001 at the upcoming APS Division of Atomic, Molecular, and Optical Physics (DAMOP) meeting in Williamsburg from May 29-June 1.)

(Editor's Note: This story, with some editing, is taken from PHYSICS NEWS UPDATE, the American Institute of Physics Bulletin of Physics News Number 588, May 9, 2002, by Phillip F. Schewe, Ben Stein, and James Riordon.)


[Contact: Randy Hulet]

14-May-2002