Time-dependent Real-space Renormalization-Group Approach: application to an adiabatic random quantum Ising model

TL;DR

This paper introduces a time-dependent real-space renormalization-group method for analyzing adiabatic, random quantum Ising models, enabling the study of ground state properties and defect formation during parameter evolution.

Contribution

It develops a novel time-dependent RG approach applicable to Hamiltonians with dynamic randomness, connecting adiabatic dynamics to critical phenomena and defect scaling.

Findings

Successfully computes off-critical flows and ground state properties.

Establishes a scaling relation for defect density during adiabatic passage.

Links RG analysis with Kibble-Zurek mechanism in quantum systems.

Abstract

We develop a time-dependent real-space renormalization-group approach which can be applied to Hamiltonians with time-dependent random terms. To illustrate the renormalization-group analysis, we focus on the quantum Ising Hamiltonian with random site- and time-dependent (adiabatic) transverse-field and nearest-neighbour exchange couplings. We demonstrate how the method works in detail, by calculating the off-critical flows and recovering the ground state properties of the Hamiltonian such as magnetization and correlation functions. The adiabatic time allows us to traverse the parameter space, remaining near-to the ground state which is broadened if the rate of change of the Hamiltonian is finite. The quantum critical point, or points, depend on time through the time-dependence of the parameters of the Hamiltonian. We, furthermore, make connections with Kibble-Zurek dynamics and provide a scaling argument for the density of defects as we adiabatically pass through the critical point of the system.