Stanford Engineering Library Blog

Umran Inan, a professor of electrical engineering, was awarded the 2007 Allan V. Cox Medal for Faculty Excellence Fostering Undergraduate Research during the Electrical Engineering Department's diploma ceremony last month.

Inan, who earned his PhD from Stanford in 1977 and joined the faculty in 1982, is the director of the Space, Telecommunications and Radioscience (STAR) Laboratory and the head of the Very Low Frequency (VLF) Research Group.

The Cox Medal is awarded annually to a faculty member who has established a record of excellence directing undergraduate research over a number of years, or who has done an outstanding job with one or two undergraduates whose work is remarkably superior.

In the citation, Inan was recognized for:

His excellence in teaching undergraduates and his long-standing commitment to providing many with research opportunities through the Research Experience for Undergraduates program in Electrical Engineering;

Challenging undergraduates with high-impact, advanced work that offers an excellent learning experience, drives academic development and elicits significant contributions from them;

His leadership in creating a large, diverse group, a research community with a strong sense of common purpose, mutual support and dedication to undergraduate research;

Taking an interest in the whole student, his/her work and passions, and for meeting with each in weekly sessions despite heavy responsibilities as director of the STAR Lab and head of the VLF Research Group;

Acting as a role model whose own passion, excellence and leadership inspire many undergraduates to undertake graduate work and devote their lives to research.
The Cox Medal was established in memory of the late Allan Cox, a professor of geophysics and dean of the School of Earth Sciences, who is widely known as the co-discoverer of magnetic field reversals.

Story from: Stanford Report

Two faculty members receive grants for innovative energy research

BY JOHN CANNON

Competition for federal funding is fierce, and the odds seem even slimmer for unconventional research, regardless of its potential. But two Stanford professors will receive awards to finance their work over the next year for just that kind of outside-of-the-box thinking.

"We recognize the difficulty faculty can have, particularly early in their careers, in gaining funding for high-risk, unproven projects," said Katherine "KT" Moortgat. She is a partner at Mohr Davidow Ventures, which is sponsoring the $75,000 grants. "The MDV award aims to enable new possibilities for these extraordinary faculty innovators."

Assistant Professor Yi Cui and Associate Professor Michael McGehee, both in materials science and engineering, submitted proposals detailing projects with, according to MDV, "potential to disrupt current thinking in their field or provoke new areas of research." The Menlo Park-based venture capital firm announced the four winners of its inaugural Innovators Award (the other two are from the University of California-Berkeley) on Nov. 15.

Cui has big ideas he hopes will improve rechargeable lithium ion batteries like those found in cell phones, laptops and other portable electronic devices. But at the root of his big idea is something very small: tiny silicon filaments called nanowires that efficiently transmit charge.

"We are talking about an energy density two to three times higher than current technology, or even higher," Cui said. "Basically, we want to change the fundamental mechanism of how the battery works."

Silicon nanowires have a much higher capacity for energy than traditional carbon, at least in theory, Cui said, so they should allow a battery to hold more energy.

"The current technology is great, but we want to move it one big step further," he said. "If you charge up your laptop battery, you can use it for four hours. What if you want to use if for 24 hours? Say you're taking an international flight, and you aren't able to recharge it."

Because nanowires are so small—with a diameter 1,000 times smaller than the thickness of a sheet of paper—and there are many of them present, they provide greater total surface area to contact the chemicals in a battery than would a larger, single electrode. This increase in the area of the electrode transmitting charge should result in greater power.

McGehee is attacking the energy problem from another angle. For the past seven years, he has been studying ways to make solar cells from organic materials—that is, polymers.

"The general advantage of organic electronics is you can make large area devices at low cost," said McGehee. "Solar cells are an application where you need to cover a very large area at low cost."

A laptop, for example, uses about 100 watts of power, and to collect that from the sun would require a solar cell a square meter in area—about the size of a four-person dinner table. Imagine, then, how large an area would be required to begin to contribute to the country's energy needs as a whole. Clearly, there needs to be a more economical method of producing solar cells.

McGehee is interested in technology similar to a roll-to-roll coating machine—like the ones used to print newspapers—to roll out solar cells and increase the efficiency of production.

"We're hoping to cut the costs by a factor of five to 10," McGehee said.

Several of his students plan to start up companies after graduating, so they hope to benefit from collaboration with the venture capital firm. In turn, MDV will have access to emerging technologies and potential areas for investment.

And for McGehee and Cui, of course, it's important to have the support to try something new.

"At this point, the federal government would probably not fund this project because it's not clear we're going to be able to get it to work," McGehee said of his specific plans for the grant. "But it's nice to be able to try it because this new idea will be really exciting if it does work."

John Cannon is a science-writing intern at the Stanford News Service.

From the Stanford Report, December 27, 2007

Stanford researchers develop a quantum "light switch"

BY RACHEL TOMPA

Infinitely secure cryptography that renders any computer unhackable. Computers that can solve the structure of a complicated protein at the drop of a hat. Programs to decrypt complicated enemy secrets. Optical data connections up to 100 times faster than current technology allows.

Photons and atoms hold the power to make these innovations reality; scientists just have to figure out how to unlock their potential. Now, researchers at Stanford and the University of California-Santa Barbara have developed a quantum "light switch" that could have implications for the future of certain kinds of computing.

A team of scientists led by Jelena Vuckovic, assistant professor of electrical engineering, has succeeded in directly probing a solid quantum system with light. This finding could be a milestone on the road to building a functional "quantum computer," a machine where information is coded in individual particles that flip between different states instead of in transistors switching on and off. The finding could lead to better quantum cryptography and faster optical data connections. Their study was published in the Dec. 6 issue of Nature.

"This effect has been previously demonstrated only in complicated atomic physics systems," Vuckovic wrote in an e-mail, "but ours is the first demonstration in solid state."

Previous demonstrations of the technique on atoms suspended in a gaseous state used machines that would dwarf an office desk. Vuckovic's team used solid material on a chip smaller than a thumbnail.

Scientists have been dreaming of a quantum computer for over 25 years. In such a machine, bits of information would be encoded in systems that walk to the beat of quantum mechanics—the field of physics that describes the quirky behavior of tiny atomic and subatomic particles.

Certain problems that scientists want to answer, such as predicting the way a complicated protein will fold, which might aid drug discovery, or factoring large integers into prime numbers to decrypt encoded messages, are extremely difficult to do with classical computers. In 2005, a 200-digit number was decomposed into prime numbers using multiple computers running for 18 months—scientists estimated that it would have taken one relatively speedy computer over 50 years to do the same task. A single powerful quantum computer, if it existed, could have done it in minutes.

One of the difficulties in actually creating a quantum computer comes from the fact that no one particle can do it all, said Dirk Englund, doctoral student in applied physics and one of the lead authors of the study. Photons are great for carrying information, and they are easy to move around, but they can't interact with each other. Conversely, atoms can interact, but can't easily communicate information. Scientists hope to get around this problem by using both, through something called a quantum network that would connect a series of atoms with a photonic channel. "In this approach, you're trying to exploit the best parts of both the atom and the photon," Englund said. "Communicate with the photon, interact with the atom."

But the problem of how to transfer the information between a single atom and a single photon still remains. If you just lob a photon at an atom, chances are it will miss, Englund said. So to give the photon a fighting chance at finding the atom, the scientists built a cavity of mirrors. The photon shoots into the cavity from a finely tuned laser beam and, like a pinball in a pinball machine, it ricochets around and around until it finally hits its target.

In this case, the target is an artificial atom termed a "quantum dot"—a microscopic blob of semiconductor material—nestled in a cavity inside another semiconductor. The blob confines charged particles to a tiny volume, much like an atom confines electrons in the tiny boundaries of its shell. Because of this confinement, the quantum dot behaves much as an artificial atom, including the ability to occupy different energy states that could represent the binary "ones" and "zeros" of digital information. If you think of the quantum dot like a spinning top, Englund said, "you'd call a spinning top that's upright a 'one' and a spinning top that pointed down a 'zero.'"

When the quantum dot is inside the semiconductor cavity, the cavity can be switched from transparent to opaque when the laser beam shines on it—meaning the team of researchers has succeeded in making a light switch out of just one photon and one quantum dot. The team includes study co-authors Andrei Faraon and Ilya Fushman, doctoral students in applied physics.

Previous groups had probed the quantum dot/cavity pair using indirect methods, but nobody had ever directly accessed the quantum system with photons before, Englund said. A research team from the California Institute of Technology published a study in the Dec. 6 issue of Nature that also demonstrates direct probing of a quantum system with photons, using a different system and technique.

The tiny chips used by Vuckovic's group have the advantage that they could easily be manufactured using technologies similar to those for computer chip manufacturing, Englund said.

While it will probably be a while before Vuckovic's system challenges the transistor as a new computational unit of information, it has that potential, Englund said. The next important step is to make some changes to the quantum dot to demonstrate that information can actually be transferred from the photonic channel to the dot—that is, to show that a piece of information from the photon could be relayed by changing the dot's energy state or spin direction.

Quantum dots might pave the road to the computer of the future, but that doesn't mean quantum computers will stock the shelves of your local electronics store, Englund said. Quantum information devices are most sought after because of their special applications to certain problems, such as unbreakable encryption systems and simulations of intricate molecular structures.

"In the next 20 years you might well see a quantum computer in a scientific research setting or defense," Englund said, "but you won't see Dell making one."

The paper's other authors are Nick Stoltz and Pierre Petroff of the University of California-Santa Barbara.

Funding for the study was provided by the Office of Naval Research, the Okawa Foundation, the U.S. Department of Defense, the U.S. Army, the U.S. Disruptive Technology Office, the Center for Integrated Systems at Stanford and the National Science Foundation.

Rachel Tompa is a science-writing intern at the Stanford News Service.

From the Stanford Report, December 7, 2007

Congratulations to SoE's David A.B. Miller on his election to the National Academy of Sciences in recognition of his contributions to scientific research. Prof. Miller is currently the W. M. Keck Foundation Professor of Electrical Engineering at Stanford, Director of the the Solid State and Photonics Laboratory at Stanford, and a Co-Director of the Stanford Photonics Research Center. More