Quench-Probe Setup as Analyzer of Fractionalized Entanglement Spreading

TL;DR

This paper introduces a new inhomogeneous setup to detect fractionalized excitations like Majorana zero modes through entanglement dynamics after a quantum quench, providing a sensitive dynamical signature without needing a topological initial state.

Contribution

It proposes a novel quench-probe setup for revealing fractionalized excitations via entanglement signatures, especially identifying Majorana zero modes through entanglement entropy jumps.

Findings

Detection of a $rac{ ext{log}(2)}{2}$ entanglement entropy jump associated with Majorana zero modes.

The setup is highly sensitive to the localized nature of Majorana modes.

No topological initial state preparation is required for detection.

Abstract

We propose a novel spatially inhomogeneous setup for revealing quench-induced fractionalized excitations in entanglement dynamics. In this quench-probe setting, the region undergoing a quantum quench is tunnel-coupled to a static region, the probe.Subsequently, the time-dependent entanglement signatures of a tunable subset of excitations propagating to the probe are monitored by energy selectivity. We exemplify the power of this generic approach by identifying a unique dynamical signature associated with the presence of an isolated Majorana zero mode in the post-quench Hamiltonian. In this case excitations emitted from the topological part of the system give rise to a fractionalized jump of $\log(2)/2$ in the entanglement entropy of the probe. This dynamical effect is highly sensitive to the localized nature of the Majorana zero mode, but does not require the preparation of a topological initial state.