Pretty much the limiting case for nanotechnology

At the very frontier of nano-technology are researchers' endeavors to control and leverage the quantum nature of matter. Unlike the messily analog world we're used to, the quantum world offers the potential of orderly, defined states which can be used for fast and dense calculation and storage. Nanowerk reports on some interesting and rather beautiful work performed at IBM more than a decade ago but newly spotlighted in an art exhibit, of all things, at the United States Patent and Trademark Museum in Alexandria, Virginia:

Driven by their discovery of the STM's ability to image the wave patterns (more precisely known as the "density distribution") of electrons on the surface of a metal, IBM Scientists Michael Crommie, Chris Lutz and Don Eigler (the "artists") were compelled to take the next step -- building an electron's "quantum state" to their own design. Here they have positioned 48 iron atoms into a circular ring in order to "corral" some of the surface electrons and force them into quantum states determined by the circular corral walls. The ripples in the ring of atoms are the wave patterns of some of the electrons that were trapped in the corral. The mechanics-turned-artists were delighted to discover that they could quantitatively account for the behavior of the electrons by solving a classic problem in quantum mechanics -- a particle in a hard-wall box -- paving the way for building functional quantum states for potential use in future computer chips and other areas.

More fascinating images and discussion are posted at http://www.almaden.ibm.com/vis/stm/gallery.html

Nanowerk notes,

IBM researchers continue using STM technology in an effort to pave the way for circuits made from atomic and molecular components. Such circuits could enable computers with hundreds of thousands of times more logic elements on a chip than today's state-of-the-art technology. That, in turn, could lead to smaller, faster, lower-power and even more portable computers and devices nobody has even imagined yet.

They also provide a nice "timeline of the legacy of IBM's Nobel Prize-winning Scanning Tunneling Microscope":

• 1981: Invention of the STM
• 1986: IBM Researchers Gerd Binnig and Heinrich Rohrer win the Nobel Prize in
  physics for inventing the STM
• 1990: For the first time, the ability to position individual atoms is
  demonstrated by spelling out "I-B-M" using xenon atoms
• 1993: Quantum Corrals created
• 1998: Discovery of molecular wheels
• 2000: Discovery of the quantum mirage effect
• 2002: Molecule cascade created
• 2004: Single-atom magnetic measurement achieved
• 2006: Ability to control atomic magnetism achieved