Probing the Quantum Collisions of Atoms Image 3
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Probing the Quantum Collisions of Atoms (Image 3)

June 29, 2010
Probing the Quantum Collisions of Atoms (Image 3) Colliding a clock atom with atoms in another state. When the clock atoms collide, they experience a discrete time jump, which is the difference of two s-wave phase shifts. The s-wave phase shifts can be measured with atomic-clock accuracy and give precise information about the atom-atom interactions. Kurt Gibble, associate professor of physics at Penn State University, is the principal investigator of a research team that developed an innovative way to study atomic collisions in a cesium fountain clock--the kind of atomic clock used to keep the world's standard of time. Atomic clocks use the quantum oscillations of ultra-cold atoms, which tick at regular intervals, to gauge the passage of time. The Penn State team was able to measure accurately the shift in the atom's quantum oscillations, or phase shifts, that it experiences during a collision with another atom. These phase shifts, which cause jumps in the atom's ticks, limit the accuracy of the world's most accurate atomic clocks. Until this study, these shifts had been impossible to measure with high precision because earlier techniques relied on knowing the atom's density, which cannot be measured accurately. Support for this research was provided by the National Aeronautic and Space Administration, the National Science Foundation, the Office of Naval Research, and Penn State University. A research paper describing this work was published in the 19 April 2007 edition of the journal Nature. For further information, see the Penn State news story New Method to Directly Probe the Quantum Collisions of Individual Atoms. (Date of Image: 2007) [One of four related images. See Next Image.]

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