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November 18, 2005

Quantum optics research earns medal from Japanese emperor

By David Orenstein

Stanford University electrical engineering and applied physics Professor Yoshihisa Yamamoto, whose research has helped to advance new methods of communications and computing based on the quirky properties of quantum physics, received the Medal with Purple Ribbon from Emperor Akihito of Japan in a Nov. 16 ceremony at the imperial palace in Tokyo.

The Medal with Purple Ribbon is one of Japan's Medals of Honor—high-profile government awards given for contributions to the arts, academics or sports. A total of 19 people received medals from the emperor at the ceremony.

A citizen of Japan, Yamamoto has been a member of the Stanford faculty since 1991 and is also a professor at Japan's National Institute of Informatics. He said that the award belongs to the entire community of researchers that has been laboring to study and apply quantum optics, the branch of physics that governs the behavior of light particles. "It is a very small field and mostly neglected in the last 50 years," he said. "It has never been recognized as an important scientific branch until recently."

Yamamoto's medal comes only a month after the Nobel Prize committee recognized Harvard physicist Roy Glauber for establishing the fundamental and theoretical underpinnings of the field. Yamamoto focuses on applications of quantum optics that could yield more secure telecommunications, more powerful computers and new methods of analyzing materials.

Applying weirdness

Quantum physics—the laws of nature that dominate at atomic and subatomic scales—is notorious for seeming counterintuitive. Yamamoto and others have slowly begun to understand these weird phenomena well enough to conceive of new technologies that can exploit them.

One phenomenon, for example, is that particles can occupy many states of a particular property at once, but those properties become fixed in just one state upon detection or measurement. Because of this fragility, no one can intercept the data that the particles of light called "photons" represent without tipping off the authorized parties at either end of the line. This makes quantum optical communications a secure way to deliver "keys" for encoding and decoding messages. Yamamoto's research group at Stanford has devised a way to transmit such keys over distances as long as 60 miles before they peter out.

For quantum optics to be useful for global communications, information must be able to traverse thousands of miles. Yamamoto is one of several researchers worldwide working to build optical devices to enable that.

In the longer term, Yamamoto says that quantum optical communications could facilitate information processing. In a quantum computer, photons would carry information from atom to atom where subatomic particles, such as electrons, would process the information in novel ways to perform tasks much faster than current binary computers.

"We have learned a lot from other people's work over many years," Yamamoto says. "I'm not sure any scientific achievement can be attributed to any single individual."

David Orenstein is the communications and public relations manager at the Stanford School of Engineering.

Editor Note:

A photo of Yamamoto is available on the web at (slug: "purple").



David Orenstein, School of Engineering: (650) 736-2245,


Yoshihisa Yamamoto, Electrical Engineering: (650) 725-3327,

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