ausblenden:
Schlagwörter:
General Relativity and Quantum Cosmology, gr-qc, Physics, Optics, physics.optics
Zusammenfassung:
The spin Hall effects of light represent a diverse class of
polarization-dependent physical phenomena involving the dynamics of
electromagnetic wave packets. In a medium with an inhomogeneous refractive
index, wave packets can be effectively described by massless spinning particles
following polarization-dependent trajectories. Similarly, in curved spacetime
the gravitational spin Hall effect of light is represented by
polarization-dependent deviations from null geodesics. In this paper, we
analyze the equations of motion describing the gravitational spin Hall effect
of light. We show that these equations are a special case of the
Mathisson-Papapetrou equations for spinning objects in general relativity. This
allows us to use several known results for the Mathisson-Papapetrou equations,
and apply them to the study of electromagnetic wave packets. We derive
conservation laws, we discuss the limits of validity of the spin Hall
equations, and we study how the energy centroids of wave packets, effectively
described as massless spinning particles, depend on the external choice of a
timelike vector field, representing a family of observers. In flat spacetime,
the relativistic Hall effect and the Wigner(-Souriau) translations are
recovered, while our equations also provide a generalization of these effects
in arbitrary spacetimes. We construct a large class of wave packets that can be
described by the spin Hall equations, but also find its limits by giving
examples of wave packets which are more general and are not described by the
spin Hall equations. Lastly, we examine the assumption that electromagnetic
wave packets are massless. While this is approximately true in many contexts,
it is not exact. We show that failing to carefully account for the limitations
of the massless approximation results in the appearance of unphysical centroids
which are nowhere near the wave packet itself.
