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.