In a virtuoso demonstration of nanotechnology, researchers used a scanning tunneling microscope (STM) to build walls of carbon monoxide molecules to confine electrons on a copper surface so that they resonate like a drum. They found that electrons confined by differently shaped walls resonated in the same way, that is, they shared the same properties. The researchers expect that this nanotech insight will prove useful in constructing real nanoelectronic systems and in obtaining information about quantum systems that is normally difficult to obtain.
From Science Daily “Hearing the sound of quantum drums“:
Using a tunneling scanning microscope and two roomfuls of equipment to move around individual carbon monoxide molecules on a copper surface, [Stanford physicist Hari Manoharan and his team] built tiny walls only one-molecule high and shaped them into nine-sided enclosures that could resonate like drums (because of the quantum wave/particle duality of the electrons within the enclosure).
Manoharan calls these enclosures quantum drums. Each drum has only 30 or so electrons inside. They are walled in by roughly 100 carbon monoxide molecules.
The result? Just as in the normal world, two nanostructures with different shapes can resonate in the same way, a phenomenon known as isospectrality. Manoharan, along with his graduate student Chris Moon and others, published their result in the Feb 8 edition of the journal Science. To reinforce the point, they created a video, complete with two quantum drums beating with the same sound. (The real “sound” is at ultra-high frequencies in the terahertz range; in the video, the sound has been converted to the range of human hearing.)
The practical value of having two different nanostructures with identical properties may lie in the design of ever-smaller computer chip circuits, Manoharan said. Designers of nano-electronic circuits will have two ways to get the same result. “Now your design palette is twice as big,” he said.
While the chip industry attempts to shrink existing circuitry, Manoharan is literally coming from the opposite direction. “My research asks, what if you start at the bottom of the ladder? We assemble structures one atom at a time,” he said. The unexplored gap between bottom-up research and the industry’s shrink-down effort “is where the excitement is,” he said.
The Stanford University press release has links to Prof. Manoharan’s web sites, a video version of the researchers explaining their work, and the sound of quantum drums, converted from the Terahertz to the Kilohertz region.
—Jim
