Abstract
A photoresponse at THz frequencies of a quantum point contact fabricated on a CdTe/CdMgTe quantum well was studied at low temperatures as a function of magnetic field. The spectra show a structure which was interpreted as resulting from the cyclotron resonance and magnetoplasmon excitations. The wavelength of the fundamental magnetoplasmon mode was found to be about 2 mu m which coincides with one of dimensions of the point contact. We also discuss the possibility of coupling of magnetoplasmon modes to shallow impurity transitions in the quantum well.