Efficient anharmonic phonon generation using a quasiperiodic lattice

The effects of anharmonic interactions on the phonon modes in quasiperiodic systems are studied by looking at the time-evolution Fourier spectrum. The results reveal an efficient generation of high-amplitude harmonics in Fibonacci chains. We also perform an energy-level-spacing analysis of the spectrum. Anharmonic contributions do clearly manifest by changing the level clustering behavior observed in quasiperiodic chains, and contrary to the periodic case, where the distribution is insensitive to weak anharmonic interactions. This result suggests a structural instability of the self-similar vibrational spectrum in quasiperiodic systems.