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Physics @ Berkeley
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Events in Physics
Title: (Anti-)matter Waves For Researching Time, Mass, And Gravity    (Colloquia)
Start Date: 10/28/2013
Time: 4:15 pm
Location: 1 LeConte Hall
Speaker: Holger Mueller
Affiliation: Assistant Professor, UC Berkeley
Contact Person: Sarah Wittmer   (510) 642-3034
What is time? We have built a clock that measures time based on the oscillation frequency mc^2/h of a particle's matter wave. The clock shows that time is physical as long as the universe has massive particles. It is based on a light-pulse atom interferometer which is self-referenced by stabilizing the frequency of the light pulses to the interferometer's interference fringes via a frequency comb generator. Used the other way around, the clock offers a new way of defining the unit of mass, replacing the last unit that is still defined by an artifact with a definition based on the fundamental constants c and h. Matter waves have also been used to test the theory of General Relativity, comprehensively ruling out violations of the equivalence principle with high precision. In the future, we hope to perform such experiments with antiparticles, measuring the gravitational influence on antimatter. As a speculation, maybe clocks can be made of an even stranger creature: the quantum vacuum.