|UCLA Researchers J. Fraser Stoddart (left) and James Heath announced significant progress in their attempts to develop a reconfigurable molecular switching element.|
Writing in the 18 August 2000 issue of the journal Science, a team of UCLA chemists led by James Heath and J. Fraser Stoddart, reported it has succeeded in using a molecule to create an electronic switch that can be reconfigured turned on and off, and on again like a transistor.
Such a result would be a significant step toward the creation of molecular computers. Previous research had produced molecular switches that could change their state only once, or could operate only for a limited time or at very low temperatures.
The new work builds on the results of a collaborative effort by researchers at UCLA and Hewlett-Packard Labs, which was reported last year (see the Recent Progress, Media Watch and Web Watch columns in Update 38 and Update 39). That work by the HP/UCLA team, which included James R. Heath of UCLA and Stanley Williams and Phil Kuekes at HP Labs, has been nominated for the 2000 Annual Feynman Prize for experimental research (see related story in this issue). In June, Heath and Williams were awarded the Julius Springer Prize for Applied Physics, one of the most prestigious international awards in the field, for their work in nanotechnology and molecular electronics.
"Last year's paper was the first experimental step toward molecular computers," said James R. Heath of UCLA, one of the team leaders. "This is the second experimental step, and the steps are no longer a slow walk, but a fast jog . . . Overall, the progress is faster than any of us expected."
The UCLA research team gives much of the credit to the unique molecules developed by Stoddart and his team. Stoddart has been working for more than a decade on interlocking molecules with recognition sites.
Stoddart came to UCLA from England's University of Birmingham, where he was head of the school of chemistry and professor of organic chemistry. "I tried to get collaborators to work on a molecular computer in Europe, but I drew a blank," Stoddart said. "It was all a dream until I came to UCLA."
Called catenanes, they consist of two tiny mechanically interlocked rings of atoms. In the team's molecular switch, one ring can be stimulated to move between two different states with respect to the other reference ring, giving the catenane molecule its bistability. The switching can be induced by removing and restoring an electron.
The UCLA chemists say the catenanes work much better than last year's rotaxanes, and they are already experimenting with more than a half-dozen different kinds of molecular switches that may yield significantly better switching performance than the catenanes.
In last year's Science paper, the researchers could switch the molecules only once; now they have done so hundreds of times.
"Last year, we published an architectural demonstration with molecules and demonstrated that it is possible to do simple mathematical operations," Heath said. "However, the switches used in that work switched only once, and this limited their relevance to any serious technology. Now we have taken another class of Fraser's molecules and demonstrated that they may be repeatedly switched on and off over reasonably long periods of time in a solid-state device under normal laboratory conditions. For the first time, we are able to turn the molecular switches on and off repeatedly."
Within a few years, Heath thinks the research team will develop circuits that have molecular logic, molecular memory and nano-size wires. A hybrid computer that interfaces molecular memory with silicon logic is only a few years away, and a scientific demonstration of a nano-scale computer that is largely molecular with molecular logic and molecular memory will likely happen within the decade, Heath estimated.
Heath believes eventually there may be a new molecular manufacturing technology. "What once seemed like science fiction is now looking more and more like actual science," Heath said. "A molecular computer will enable us to do things we cannot even imagine now."
"Molecular machines will lead to other new technologies beyond molecular electronic computers," Stoddart said. "Other fields besides computers may be revolutionized by this molecular approach, although it is too soon to say precisely which ones will be the first to benefit."
In addition to conducting this research, Heath is a leader of a joint proposal by UCLA and UC Santa Barbara to create a wide-ranging California Nanosystems Institute that could help revolutionize many fields of science. The project has been chosen as a finalist in the competition for one of the California Institutes for Science and Innovation proposed by Gov. Gray Davis. The UCLA-UCSB collaboration focuses primarily on molecular medicine and information technology.
The research reported in Science was funded by the Defense Advanced Research Projects Agency (DARPA).
In article from the Houston Chronicle ("Nanotechnology development may drastically alter computing," by Tom Fowler, 15 August 2000), a leading molecular electronics researcher issued his own challenge in the increasingly competitive race to commercialize this new nanoscale technology.
"I want to see us run up the tail of every chip maker around," the article quotes Jim Tour of Rice University in Houston. "This will change the landscape for some huge, global industries."
Tour and Yale collaborator Mark Reed, along with a number of other partners, formed the Molecular Electronics Corporation (MEC) in December 1999 (see the report in Update 41).
Tour recalls the incredulity, even ridicule, of other reserachers in theoretical physics and chemistry which he endured when he began making presentations about his work and its potential. "Scientists can be extremely closed-minded," Tour says in the Houston Chronicle piece. "I've had reviews from my peers slamming my work for years."
But with new advances occurring week by week, and the credibility the field has gained from the advent of the National Nanotechnology Initiative, Tour, Reed and their partners chose to incorporate their molecular electronics start-up last fall. According to the Houston Chronicle:
"With the cooperation of Rice, Yale and Pennsylvania State University, the company secured rights to much of their university-sponsored research, and is busy filing patents. MEC now has a dozen or so employees spread out between the three campuses, with plans to move into a new facility near Yale this month . . . The headquarters is officially in Chicago, where CEO Harvey Plotnick lives, but as the company grows it could be anywhere, including Houston."
The article also mentions the competition MEC faces from California Molecular Electronics Corp. (CALMEC), Hewlett-Packard (see related story in this issue), and to a lesser extent from Technanogy Inc., a nanotech-oriented venture-capital firm based in Newport Beach, California. In addition, according to the Chronicle, Motorola, Hitachi and IBM all have research efforts under way, but their results have not been as widely reported as MEC's or those at UCLA.
A number of factors that place MEC at the head of the growing field of molectronics competitors are detailed:
It's been speculated by a number of analysts that the first practial commercial application of molecular electronics will be some form of computer memory, perhaps a hybrid of existing silicon technology and molecular technology as a first step toward molecular computing systems. MEC seems well on the way to delivering such a product.
A team of researchers at IBM-Almaden led by Isaac Chuang described experiments that demonstrated the world's most advanced quantum computer, which is based on a single, specially designed molecule containing five fluorine atoms. Chuang presented the results on 15 August 2000 at Stanford University at the Hot Chips 2000 conference, which is organized by the IEEE Computer Society.
An IBM press release described the research; the web version contains a number of useful links to related items.
Quantum computers operate by taking advantage of certain quantum properties of atoms or nuclei that allow them to work together as quantum bits, or "qubits," to be the computer's processor and memory.
The new IBM quantum computer contains five qubits ‹ five fluorine atoms within a molecule specially designed so the fluorine nuclei's "spins" can interact with each other as qubits, be programmed by radiofrequency pulses and be detected by nuclear magnetic resonance instruments similar to those commonly used in hospitals and chemistry labs.
Using the molecule, Chuang's team solved in one step a mathematical problem for which conventional computers require repeated cycles. The problem is called "order-finding" ‹ finding the period of a particular function ‹ which is typical of many basic mathematical problems that underlie important applications such as cryptography.
A brief article on the team's research also appeared in the 26 August 2000 issue of Science News.
From Foresight Update 42, originally published 30 September 2000.
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