Anomalous low-energy properties in amorphous solids and the interplay of electric and elastic interactions of tunneling two-level systems

Abstract

Tunneling two-level systems (TLSs), generic to amorphous solids, dictate the low-energy properties of amorphous solids and dominate noise and decoherence in quantum nano-devices. The properties of the TLSs are generally described by the phenomenological standard tunneling model. Yet, significant deviations from the predictions of this model found experimentally suggest the need for a more precise model in describing the low-energy properties of amorphous solids. Here we show that the temperature dependence of the sound velocity, dielectric constant, specific heat, and thermal conductivity, can be explained using an energy-dependent TLS density of states. The reduction of the TLS density of states at low energies relates to the ratio between the strengths of the TLS-TLS interactions and the random potential, which is enhanced in systems with dominant electric dipolar interactions.