In early 2007, Lene Hau’s “trick of the light,” stopping and switching off a light pulse in one part of space and then rekindling it in another location, gave the public and experts alike pause — just enough time to let in wonder.

The media latched on to metaphors, from the sublime (“evokes the magic of carrying moonbeams in a jar”) to the poetic (“visions in the dark of light”) to the pedestrian (“it’s like three-card Monte”). A colleague in physics, John Preskill of the California Institute of Technology, even composed a poem in honor of Hau (“But Lene Hau has built a nest/Where tired light can stop to rest”).

The pursuit of such scientific wizardry led the President and Fellows of Harvard College to award Hau, Mallinckrodt Professor of Physics and of Applied Physics, the George Ledlie Prize.

“I am very honored to receive the prize. It is really wonderful to receive this kind of recognition from your home institution,” said Hau.

The physicist’s fascination with the nature of light resulted in several breakthroughs during the past decade. In 1999, Hau slowed light down to 38 mph, or about the speed of a racing bicycle, by shooting a laser beam through incredibly cold atoms. Two years later she one-upped her own finding, bringing light to a complete standstill before restarting it and sending it once again on its path.

“The highly original discoveries of Lene and her lab remind all of us who pursue research of those ‘ah-ha’ moments that led us into the profession in the first place,” said Frans Spaepen, interim dean of Harvard’s School of Engineering and Applied Sciences (SEAS) and John C. and Helen F. Franklin Professor of Applied Physics. “I hope her success encourages the next generation of innovators to be bold, take risks, and go after the fundamental questions that really inspire them.

As with Hau’s latest discovery of exchanging light and matter, the work has life beyond the lab. Manipulating and controlling light could be of great importance for next-generation computing and lead to practical applications in optical networks and quantum cryptography.

“This feat, the sharing around of quantum information in light-form and in not just one but two atom-forms, offers great encouragement to those who hope to develop quantum computers,” said Jeremy Bloxham, dean of science in the Faculty of Arts and Sciences.

“Lene’s work is path-breaking,” added Harvard’s Provost Steven E. Hyman. “Her research blurs the boundaries between basic and applied science, draws on the talent and people of two Schools and several departments, and provides a literally glowing example of how taking daring intellectual risks leads to profound rewards.”

Hau, a recently elected member of the Royal Swedish Academy of Sciences and a 2001 MacArthur “Genius” Fellow, received her B.S., M.S., and Ph.D. degrees from the University of Aarhus in her home country of Denmark. Her Ph.D. work was in theoretical solid state physics, a field completely different from that of her later work with ultracold atoms.

In 1989, she received the prestigious J.C. Jacobsen Anniversary Fellowship, awarded by the Carlsberg Foundation of Denmark. She came to Harvard as a postdoctoral fellow to pursue research with Jene Golovchenko, Rumsford Professor of Physics and Gordon McKay Professor of Applied Physics, who held positions at Harvard and the then-independent (and now FAS-run) Rowland Institute of Science. In 1991 Hau became a member of the scientific staff and was given her own lab at Rowland; eight years later she was appointed as a tenured member of the Harvard faculty.

Hau’s current research space, easily recognizable by the ‘Day-Glo’ orange and yellow colored walls, is located in the Cruft and Lyman Laboratories of SEAS and the Physics Department.

“The experiments we do require an intense focus and often run late into the night,” said Hau. “They require teamwork, and it has been a great experience to work with [the] bright and dedicated young people — students and postdocs — we have here at Harvard. … They keep you on your toes!”

The Ledlie Prize is awarded no more than once every two years to someone affiliated with the University who “since the last awarding of said prize has by research, discovery or otherwise made the most valuable contribution to science, or in any way for the benefit of mankind.” Robert B. Woodward, the Morris Loeb Professor of Chemistry, was the first recipient in 1955. Other winners have included Judah Folkman, the Julia Dyckman Andrus Professor of Pediatric Surgery; Douglas Melton, the Thomas Dudley Cabot Professor of the Natural Sciences; Gerald Gabrielse, the George Vasmer Leverett Professor of Physics; and most recently, in 2006, Lakshminarayanan Mahadevan, Lola England de Valpine Professor of Applied Mathematics at SEAS.

And quiet flows the Don at Pusey