Dissipationless dynamics of randomly coupled spins at high temperatures

Abstract

We develop a technique to compute the high-frequency asymptotics of spin correlators in weakly interacting disordered spin systems. We show that the dynamical spin correlator decreases exponentially at high frequencies, $<SS{>}_{\omega }\sim \exp (-{\tau }_{\ast }\omega )$ and compute the characteristic time ${\tau }^{\ast }$ of this dependence. In a typical random configuration, some fraction of spins form strongly coupled pairs, which behave as two-level systems. Their switching dynamics is driven by the high-frequency noise from the surrounding spins, resulting in low-frequency $1/f$ noise in the magnetic susceptibility and other physical quantities. We discuss application of these results to the problem of susceptibility and flux noise in superconducting circuits at mK temperatures.

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Cited by in corpus (8)

• 1/f noise: implications for solid-state quantum information
• Exponentially slow heating in periodically driven many-body systems
• Environmental noise spectroscopy with qubits subjected to dynamical decoupling
• The Theory of Spin Noise Spectroscopy: A Review
• A two-way approach to out-of-time-order correlators
• Flux $1/f^{\alpha }$ noise in 2D Heisenberg spin glasses: effects of weak anisotropic interactions
• Nonequilibrium Spin Noise and Noise of Susceptibility
• Dynamical spin polarization of excess quasi-particles in superconductors