2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/99212We predict a double-resonant feature in the magnetic field dependence of the phonon-mediated longitudinal conductivity $σ_{xx}$ of a two-subband quasi-two-dimensional electron system in a quantizing magnetic field. The two sharp peaks in $σ_{xx}$ appear when the energy separation between two Landau levels belonging to different size-quantization subbands is favorable for acoustic-phonon transitions. One-phonon and two-phonon mechanisms of electron conductivity are calculated and mutually compared. The phonon-mediated interaction between the intersecting Landau levels is considered and no avoided crossing is found at thermal equilibrium.13 pages, 8 figuresMesoscale and Nanoscale Physicstext