Almost everyone has seen that wonderful first picture of a “Quantum Corral” from the now-famous paper by Crommie, Lutz and Eigler (Confinement of electrons to quantum corrals on a metal surface. Science 262, 218-220 (1993)). The surface states of the electrons on the copper substrate were coralled by a cylindrical barrier made out of iron adatoms. And waves confined to a nearly-circular box have Bessel functions as a good basis set. The second picture is a new device that uses waves to print standing patterns on water surfaces. It is a neat collaboration between Akishima Laboratories and professor Shigeru Naito of Osaka University. The device consists of 50 water wave generators encircling a cylindrical tank 1.6 meters in diameter and 30 cm deep. Once again, the cylindrical geometry makes Bessel functions a natural basis set for expanding the standing-wave pictures that are drawn on the surface. Once the Bessel function components are known, the drivers at the edge of the tank can be made to work in unison to excite that pattern.
Found via Pink Tentacle.
[tags]bessel functions, quantum corrals, water[/tags]