What are the interactions in quantum glasses?

Abstract

The form of the low-temperature interactions between defects in neutral glasses is reconsidered. We analyse the case where the defects can be modelled either as simple 2-level tunneling systems, or tunneling rotational impurities. The coupling to strain fields is determined up to 2nd order in the displacement field. It is shown that the linear coupling generates not only the usual $1/r^3$ Ising-like interaction between the rotational tunneling defect modes, which cause them to freeze around a temperature $T_G$, but also a random field term. At lower temperatures the inversion symmetric tunneling modes are still active - however the coupling of these to the frozen rotational modes, now via the 2nd-order coupling to phonons, generates another random field term acting on the inversion symmetric modes (as well as shorter-range $1/r^5$ interactions between them). Detailed expressions for all these couplings are given.

12 pages, 2 figures. Minor modifications, published version

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Cited by in corpus (13)

• Low temperature universality in disordered solids
• Cosmological Constant from Decoherence
• Proof of Rounding by Quenched Disorder of First Order Transitions in Low-Dimensional Quantum Systems
• Identification of strong and weak interacting two level systems in KBr:CN
• Non-homogeneity of the density of states of tunneling two-level systems at low energies
• Decoherence of a quantum two-level system by spectral diffusion
• Correlated random fields in dielectric and spin glasses
• Nonuniversality and strongly interacting two-level systems in glasses at low temperatures
• Anomalous low-energy properties in amorphous solids and the interplay of electric and elastic interactions of tunneling two-level systems
• Acoustic interactions between inversion symmetric and asymmetric two-level systems
• 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
• Thermal cycling -- evidence for a generalized tunneling model and a tool to distinguish noise sources in quantum circuits