Persistent Quantum Beats and Long-Distance Entanglement from Waveguide-Mediated Interactions

TL;DR

This paper investigates photon correlations and entanglement in waveguide-coupled qubits, revealing long-lasting quantum beats and non-Markovian effects that enable scalable quantum networking.

Contribution

It introduces a Green function method to analyze vacuum-mediated qubit interactions, including non-Markovian dynamics, and demonstrates long-distance entanglement generation.

Findings

Quantum beats in correlation functions persist longer than qubit lifetime.

Non-Markovian effects enable high degrees of long-distance entanglement.

Waveguide-QED systems are promising for scalable quantum networks.

Abstract

We study photon-photon correlations and entanglement generation in a one-dimensional waveguide coupled to two qubits with an arbitrary spatial separation. We develop a novel Green function method to study vacuum-mediated qubit-qubit interactions, including both spontaneous and coherent couplings. As a result of these interactions, quantum beats appear in the second-order correlation function. We go beyond the Markovian regime and observe that such quantum beats persist much longer than the qubit life time. Using these non-Markovian processes, a high degree of long-distance entanglement can be generated, making waveguide-QED systems promising candidates for scalable quantum networking.