Plasmon excitations in Josephson arrays and thin superconducting layers

Abstract
Long-wave excitations in Josephson arrays are investigated. The existence of excitations with square root or acoustic dispersion law, like plasmons in two-dimensional electron gas, is predicted. Observation of such excitations with frequency much lower than the frequency of the superconducting gap Δ/ħ is possible by use of a grating and the same far infrared or microwave techniques used for detection of the plasmons in semiconductor microstructures.