Random Nonlinear Infinite-Level-System Model for Amorphous Solid Phonon Echo and Saturation Phenomena

Abstract

The first two successful predictions for amorphous solid experiments by tunneling-two-level system (TTLS) was phonon echo 17 and saturation 18 phenomena. In this paper by generalizing TTLS to infinite-level-system model with certain randomness and nonlinearity, we prove that phonon echo is a stimulated emission process. The classical infinite-level-system (taking → 0 limit) cannot find saturation effect, while quatum infinite-level-system can find it with certain nonlinearity assumed. We also prove that without randomness or nonlinearity neither phonon echo nor saturation exists in arbitrary infinite-level-system.

Depletion of Two-Level Systems in Ultrastable Computer-Generated Glasses

“…In the subsequent decades, the generic behavior described by Zeller and Pohl has been observed in numerous other amorphous materials, and the TLS theory has withstood essentially all experimental tests [5][6][7][8][9]. Despite this great progress in our understanding, the microscopic real-space structure of the tunneling defects remains debated, as do the fac-* These authors contributed equally to the work tors that determine the density and distribution of TLS in amorphous solids [10][11][12][13][14][15][16][17][18][19][20][21][22].…”