Role of Noise on Defect Formation and Correlations in a Long-Range Ising Model Under Adiabatic Driving

TL;DR

This paper investigates how long-range interactions and noise influence defect formation, correlations, and spin dynamics in an exactly solvable long-range transverse-field Ising model during adiabatic driving.

Contribution

It provides a detailed analysis of noise effects on defect density, correlations, and mode contributions in a long-range Ising model, highlighting differences from short-range systems.

Findings

Defect density scales as τ_Q^{-1/2} in noiseless case

Long-range interactions increase defect density without noise, but suppress it with noise

Correlations exhibit Gaussian and exponential decay patterns depending on conditions

Abstract

We study an exactly solvable long-range (LR) transverse-field Ising model (TFIM) with a power-law decaying interaction characterized by a decay exponent {\alpha}. In the thermodynamic limit, the system is adiabatically driven in the presence of noise, from a paramagnetic phase with all spins down to one with all spins up. Our study examines the role of long-range interactions on the defect density, its distribution, and spin correlations, comparing noisy and noiseless scenarios. In the noiseless case, within the long-range regime, the steady-state properties are primarily influenced by modes near the k = {\pi} region. However, in the presence of noise, the dominant contributions shift to the modes near k = 0. This differs from the SR model, where previous studies have shown that modes around k = {\pi}/2 play a significant role under noisy conditions. In the absence of noise, defect density scales as $n\propto \tau_Q^{-1/2}$, implying scaling exponent independent of decay exponent. However, we find that decreasing the value of {\alpha} (i.e., increasing the range) enhances the defect density, whereas in the presence of noise, it is suppressed. In the LR regime, two-point fermionic correlators initially exhibit Gaussian decay, followed by quadratic suppression instead of power-law decay for both noisy and noiseless scenarios. Meanwhile, spin correlators, expressed as a string of fermionic operators, undergo purely exponential decay with no crossover behavior. Furthermore, our analysis of defect formation reveals the influence of LR interaction on the kink-number distribution and its cumulants.