939 research outputs found
Beams of electromagnetic radiation carrying angular momentum: The Riemann-Silberstein vector and the classical-quantum correspondence
All beams of electromagnetic radiation are made of photons. Therefore, it is
important to find a precise relationship between the classical properties of
the beam and the quantum characteristics of the photons that make a particular
beam. It is shown that this relationship is best expressed in terms of the
Riemann-Silberstein vector -- a complex combination of the electric and
magnetic field vectors -- that plays the role of the photon wave function. The
Whittaker representation of this vector in terms of a single complex function
satisfying the wave equation greatly simplifies the analysis. Bessel beams,
exact Laguerre-Gauss beams, and other related beams of electromagnetic
radiation can be described in a unified fashion. The appropriate photon quantum
numbers for these beams are identified. Special emphasis is put on the angular
momentum of a single photon and its connection with the angular momentum of the
beam.Comment: To be published in the special issue of Optics Communications
honoring Bruce Shor
Motion of vortex lines in nonlinear wave mechanics
We extend our previous analysis of the motion of vortex lines [I.
Bialynicki-Birula, Z. Bialynicka-Birula and C. Sliwa, Phys. Rev. A 61, 032110
(2000)] from linear to a nonlinear Schroedinger equation with harmonic forces.
We also argue that under certain conditions the influence of the contact
nonlinearity on the motion of vortex lines is negligible. The present analysis
adds new weight to our previous conjecture that the topological features of
vortex dynamics are to a large extent universal.Comment: To appear in Phys. Rev. A, 4 page
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