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-temperature 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 TLSs. 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 reduced at low energies due to TLS-TLS interactions. This reduction is determined by the ratio between the strengths of the TLS-TLS interactions and the random potential, which is enhanced in systems with dominant electric dipolar interactions.

arXiv comment12 pages, 7 figures

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• Two-level systems in superconducting quantum devices due to trapped quasiparticles
• Thin-film quartz for high-coherence piezoelectric phononic crystal resonators
• The strain gap in a system of weakly and strongly interacting two-level systems
• Anomalous Loss Reduction Below Two-Level System Saturation in Aluminum Superconducting Resonators