John L. Hall, a fellow and senior research associate at JILA, a joint institute of the University of Colorado at Boulder and the National Institute of Standards and Technology, has been awarded the 2005 Nobel Prize in Physics.
Hall, 71, shared the Nobel with Theodor W. H盲nsch of the Max Planck Institute for Quantum Optics and a professor of physics at Ludwig Maximilians University in Munich, Germany, and Roy J. Glauber, a professor of physics at Harvard University.
Hall and H盲nsch were awarded half the Nobel Prize for their contributions to the development of laser-based precision spectroscopy, including the optical frequency comb technique. An optical frequency comb is generated by a laser specially designed to produce a series of extremely short -- a few billionths of a second -- equally spaced pulses of light.
The other half of the prize was awarded to Glauber for his contribution to the quantum theory of optical coherence.
The call came at 3:15 a.m. today informing Hall he was a co-recipient of the physics prize. "It was quite unexpected," said Hall. "I already had worked out what I was going to say when it was announced that Ted H盲nsch had won."
According to the announcement, the important contributions by Hall and H盲nsch have made it possible to measure frequencies with an accuracy of 15 digits. Lasers with extremely sharp colors can now be constructed, and with the frequency comb technique, precise readings can be made of light of all colors.
For example, this technique makes it possible to study the stability of the constants of nature over time and to develop extremely accurate clocks and improved Global Positioning System, or GPS technology, Hall said.
Hall is known as a pre-eminent laser experimentalist, concentrating on improving the precision and accuracy with which lasers can produce a specific, sharp frequency or color of light, and the stability to hold that frequency. His work has been essential to precision spectroscopy for physical and chemical analysis, new tests and measurements of fundamental physical laws and constants, time and length, metrology and fiber-optic communications.
In the 1960s he worked on the development of the methane-stabilized helium-neon laser, which became the cornerstone of a famous experiment at NIST to measure the speed of light at least 100 times better than any previous determination. The work ultimately led to a fundamental redefinition of the meter, the basic unit of distance measurement.
Hall began his career at NIST as a National Research Council postdoctoral fellow in 1961. He joined the NIST staff as a physicist in 1962, and was named a senior scientist in 1971. In 1964, he became a fellow of JILA.
He has been affiliated with CU-Boulder's physics department since 1966, retired from NIST in 2004 and currently is a senior research associate at JILA, located on the CU-Boulder campus. Hall has been the thesis adviser of 15 physics doctoral students at CU-Boulder.
Hall said JILA "has created an environment in which excellence of research and post-graduate training can prosper. It's been a great 44 years."
He has received many honors during his career, including the Department of Commerce Gold Medal -- individually in 1969 and as part of a group in 1974 and 2002. He has been a member of the National Academy of Sciences since 1984.
One of the founding fellows of JILA, Hall's career has paralleled and fostered the development of the laser, which was first demonstrated in 1961 and which has gone from laboratory curiosity to one of the fundamental tools of modern science.
For more information, visit the Nobel Prize web site at or the NIST Web site at .