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American physicist William Philips shared the 1997 Nobel Prize in physics with two other reasearchers. Philips was recognized for his work on ways to cool and trap atoms.
William D. Philips, born in 1948, American physicist and Nobel laureate. Philips’s advancements in the use of special beams of light called lasers to slow, cool, and capture atoms (tiny particles that make up matter) were instrumental in furthering the study and use of atoms. In the late 1980s Philips used laser cooling to cool and slow atoms to a point not thought possible at the time. He shared the 1997 Nobel Prize for physics with two other scientists who made separate but complementary advancements, Steven Chu of the United States and Claude Cohen-Tannoudji of France. Their achievements led to a breakthrough in the study and manipulation of atoms, which in turn brought improvements to many applications, including global navigation and gravitational measurement techniques.
Philips was born in Wilkes-Barre, Pennsylvania. He earned a B.S. degree in physics at Juniata College in Huntingdon, Pennsylvania, in 1970. In 1976 he earned his Ph.D. degree in physics from Massachusetts Institute of Technology (MIT). After post-doctoral research at MIT, in 1978 he joined the National Institute of Standards and Technology (NIST), then known as the National Bureau of Standards.
Hired to work with precision electrical measurements, Philips soon also began conducting experiments in trapping atoms. He made advancements using a magnetic device to slow atoms. Meanwhile Steven Chu and a team at Bell Laboratories in Holmdel, New Jersey, began furthering the use of lasers to capture atoms. In 1985 Chu successfully used lasers in a vacuum chamber to cool atoms to 240 millionths of a Celsius degree (430 millionths of a Fahrenheit degree) above absolute zero, the point at which all matter stops moving (–273.15° C, or -459.67° F).
Philips adopted Chu’s techniques, and by 1988 Philips and his research team had cooled atoms to 40 millionths of a Celsius degree (70 millionths of a Fahrenheit degree) above absolute zero, lower than scientists thought was theoretically possible at the time. Philips came up with methods to capture atoms at regular intervals in what was termed an optical lattice.
At room temperature, atoms move at speeds of about 4000 km/h (2500 mph), much too fast for scientists to study them. The rate at which atoms move is related to the temperature of the matter made up by the atoms. Lowering the temperature of the sample of atoms slows the atoms’ motion, and vice versa. Chu and Philips developed techniques in which atoms are bombarded with finely tuned laser beams. The lasers immerse the atoms in packets of light wave energy called photons. The photons strike the atoms in a way that is roughly like raindrops hitting a beach ball. The photons have no mass, but because they travel at the speed of light, they carry enough momentum to hit the atoms and slow them down. By 1995 Claude Cohen-Tannoudji and his team used similar techniques to lower the temperature of a sample of atoms to 0.2 millionths of a Celsius degree (0.4 millionths of a Fahrenheit degree) above absolute zero.
The ability to manipulate atoms and study them more closely led to many immediate and many potential applications. Trapped atoms have increased the accuracy of atomic clocks, which increases the accuracy of other instruments that use atomic clocks, such as navigation systems. Control of atoms also helps calibrate instruments used to measure the force of gravity at spots on the earth. These measurements indicate different densities within the earth, which can reveal features such as petroleum deposits beneath the earth’s surface. The ability to manipulate atoms also raises the possibility of using atoms to etch electronic circuits, thereby increasing the circuits’ capabilities by increasing the number of circuits that can fit in a certain area.
In the 1990s Philips continued his research into ultra-cold trapped atoms. In 1995 he was elected to the American Academy of Arts and Sciences and became an NIST Fellow. Two years later he was named to the National Academy of Sciences.