University of Connecticut

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Atomic, Molecular, and Optical Physics Seminar

Monday, March 20, 2017
4:00pm – 5:00pm

Storrs Campus
Physics Building, P121

Dr. Mikko Partanen, Aalto University, Finland

Momentum and mass in the covariant theory of light in a medium

We have recently developed a novel covariant theory of light in a medium by considering a light wave simultaneously with the dynamics of the medium driven by the optomechanical forces between the induced dipoles and the electromagnetic field. One of the most fundamental consequences of our theory following directly from the covariance principle and the fundamental conservation laws of nature is that a light pulse having a total electromagnetic energy E0 propagating in a nondispersive medium transfers a mass equal to δM = (n^2−1)E_0/c^2, where n is the refractive index. This mass is made of atoms, which are more densely spaced inside the light pulse due to the optomechanical forces. The predicted photon mass drag effect leads to dissipation of photon energy and it also gives an essential contribution to the total momentum of the light wave, which becomes equal to the Minkowski momentum p=nE_0/c. Therefore, our theory also gives a unique resolution to the centenary Abraham-Minkowski controversy of the momentum of light in a medium. In the case of a silicon single crystal, the atoms moving due to the field-dipole forces carry in the optical regime about 92% of the total momentum of the light pulse. We finally discuss a possibility of an optical waveguide setup for experimental measurement of the transferred mass of the light pulse. Our main result that a light pulse is inevitably associated with an experimentally measurable mass is a fundamental change in our understanding of light propagation in a medium.


Prof. Phillip Gould

Physics Department (primary)

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