In one minute

Thomas Philbin builds on the Casimir effect's central lesson, that the zero-point energy of the electromagnetic vacuum has real physical consequences. He models quantum light travelling in one dimension past a block of material, including full dispersion and absorption. The block pushes the zero-point energy below its free-space value at some frequencies and raises it at others. The regularised Casimir energy per frequency also drops below zero, the free-space value, at some frequencies. The total Casimir energy is positive, and single-mode zero-point quantities have direct experimental meaning through homodyne detection and spontaneous emission.

Damped vacuum states of light