Hau Receives Tenure; Physics Professor Slowed Light

Lene Verstergaard Hau, the Danish physicist who announced last February that she had slowed down light, has been appointed to a tenured post in Harvard's physics department and Division of Engineering and Applied Sciences (DEAS).

Hau, who in September became McKay professor of applied physics, reported with two other researchers in the science journal Nature that they had slowed light to 17 meters per second.

Hau, who is one of four experimental physicists added to the Faculty in the last year, says she hopes to slow light to a centimeter per second within a month.

"We think of light as very quick and very fast, but she has been able to slow down light to the speed of a racing bicycle," said David R. Nelson, Mallinckrodt professor of physics and chair of the department.

The process involves supercooling sodium until it becomes a "Bose-Einstein condensate," and then using quantum interference to slow the light as it passes through the condensate.

Hau said her process will be useful in building highly sensitive optical switches--switches that can be thrown by a single photon.

"If we can somehow find a way to make this system more practical--it's not yet the sort of thing you can fit in a knapsack--it would have fantastic applications," Hau said.

According to Venkatesh G. Narayanamurti, dean of DEAS and also McKay professor of applied physics, that day of knapsack light decelerators may be soon.

"If history is any guide, 10 years from now this big laboratory curiosity could well become the right size," Narayanamurti said.

According to Narayanamurti, Hau's work opens new possibilities for interdepartmental research.

"Harvard has a fine tradition with nonlinear optics and atomic physics, and Lene brings these things together in unusual ways, which will probably mean new connections with [DEAS] and physics," he said.

Hau, who has been a member of the research staff at the Rowland Institute for Science in Cambridge's Kendall Square since 1991, has team-taught a Harvard first-year seminar, "Physicists and Scientific Problems," with another McKay professor of applied physics, Jene A. Golovchenko, for the last five years.

Hau became interested in slowing down light and Bose-Einstein condensates in the late 1980s, while a graduate student at the University of Aarhus in Denmark.

"I became aware that there was this new field emerging, that you could use lasers to cool atoms down to extremely low temperatures," Hau said. "Each time you cool, you move into a new regime of nature, and that's where new things are bound to happen."

In 1991, she joined Harvard as a postdoctoral fellow.

"I definitely had plans to go back to Denmark. I had plans to be here for two years," Hau said.

She said she then received word from the Rowland Institute, a research group, that she would be granted funds and laboratory space for her dream research.

"I thought, 'That sounds really good. I think I'm staying here,'" Hau said.

Hau said her eight years at the Rowland Institute have been time well spent.

"It was a very good place for [me as] a young person," she said. "You really get to worry about science and develop scientifically in your early years."

But now, Hau says, she is ready for a change.

"I felt this was a time in my life when I would really like to teach and deal with students," Hau said. "And I think with my background--having worked really heavy-duty scientifically--I have a strong background to do that.

Hau, who was courted by Princeton and Stanford Universities as well as the University of Illinois, said the major draws of Harvard were its students and facilities, particularly the center for mesoscale structures that is currently in planning stages.