We consider conduction-electron dephasing by the zero-point fluctuation of an electromagnetic field in a vacuum. We argue that there is an upper cutoff frequency of the zero-point fluctuation mode beyond which the zero-point fluctuation will not contribute to the dephasing of conduction electrons. The upper cutoff frequency is material-parameter dependent. We find that the dephasing time is proportional to the electron diffusion constant. This result agrees very well with existing experimental data.

• Received 2 November 1999

DOI:https://doi.org/10.1103/PhysRevB.61.R5090