Edge magnetoplasmons arise on a boundary of conducting layer in perpendicular
magnetic field due to an interplay of electron cyclotron motion and Coulomb
repulsion. Lateral electric field, which confines electrons inside the sample,
drives their spiraling motion in magnetic field along the edge with the average
drift velocity contributing to the total magnetoplasmon velocity. We revisit
this classical picture by developing fully quantum theory of drift velocity
starting from analysis of magnetic edge channels and their electrodynamic
response. We derive the quantum-mechanical expression for the drift velocity,
which arises in our theory as a characteristic of such response. Using the
Wiener-Hopf method to solve analytically the edge mode electrodynamic problem,
we demonstrate that the edge channel response effectively enhances the bulk
Hall response of the conducting layer and thus increases the edge
magnetoplasmon velocity. In the quasiclassical long-wavelength limit of our
model, the drift velocity is simply added to the total magnetoplasmon velocity,
in agreement with the classical picture.Comment: 10 pages, 6 figure