Electromagnetic energy-momentum in dispersive media
Philbin, Thomas G.
Physical Review A
American Physical Society
The standard derivations of electromagnetic energy and momentum in media take Maxwell’s equations as the starting point. It is well known that for dispersive media this approach does not directly yield exact expressions for the energy and momentum densities. Although Maxwell’s equations fully describe electromagnetic fields, the general approach to conserved quantities in field theory is not based on the field equations, but rather on the action. Here an action principle for macroscopic electromagnetism in dispersive, lossless media is used to derive the exact conserved energy-momentum tensor. The time-averaged energy density reduces to Brillouin’s simple formula when the fields are monochromatic. The time-averaged momentum density for monochromatic fields corresponds to the familiar Minkowski expression D×B, but for general fields in dispersive media the momentum density does not have the Minkowski value. The results are unaffected by the debate over momentum balance in light-matter interactions.
Copyright © 2011 American Physical Society - original article
Copyright © 2012 American Physical Society - erratum
PDF incorporates the Erratum to the published version
Vol. 83 (1), article 013823 - original article; Vol. 85 (5), article 013823 - erratum