Faraday quantum clock and nonlocal photon pair correlations

We study the use of the Faraday effect as a quantum clock for measuring traversal times of evanescent photons through magnetorefractive structures. The Faraday effect acts both as a phase shifter and as a filter for circular polarizations. Only measurements based on the Faraday phase-shift properties are relevant to the traversal time measurements. The Faraday polarization filtering may cause the loss of nonlocal (Einstein-Podolsky-Rosen) two-photon correlations, but this loss can be avoided without sacrificing the clock accuracy. We show that a mechanism of destructive interference between consecutive paths is responsible for superluminal traversal times measured by the clock.