Propagation of local excitations through strongly correlated quantum chains

TL;DR

This paper investigates how local excitations propagate through strongly correlated quantum spin chains, revealing wave-like behavior, velocity bounds, and their relation to Lieb-Robinson limits.

Contribution

It provides a detailed analysis of the propagation dynamics of local excitations in quantum chains, including velocity bounds and wave characteristics.

Findings

Propagation resembles a classical wave with multiple frequencies.

Group velocity varies and is bounded by Lieb-Robinson limits.

Propagation speed depends on chain size and system parameters.

Abstract

The propagation of an external transverse magnetic signal acting locally on a 1d chain of spins generates a disturbance which runs through the system. This quantum effect can be interpreted as a classical traveling wave which contains a superposition of a large set of frequencies depending on the size of the chain. Its local amplitude fixes the size of the z-component of the spins at any location in the chain. The average and maximum value of the group velocity are determined and compared with the transmission velocity fixed by the Lieb-Robinson upper bound inequality.