Distribution of Bell State Entanglement in Qubit Networks via Collision Models

TL;DR

This paper introduces a collision model-based scheme for controllably distributing Bell state entanglement across qubit networks, adaptable to various interaction patterns and applicable in quantum communication and computing.

Contribution

It presents a novel collision model framework for entanglement distribution that includes both traditional and repeated interaction scenarios, enabling selective entanglement generation.

Findings

Maximally entangled Bell pairs can be generated between non-neighboring qubits.

The scheme works in small networks up to three qubits.

Both collision and repeated interaction models are effective for entanglement distribution.

Abstract

We propose a general scheme to controllably distribute pairwise entanglement in a quantum network of qubits by exploiting environmental ancilla qubits interacting with the network nodes through tunable Hamiltonians. Our approach leverages collision models, in which a quantum syatem interacts sequentially with ancilla units. We explore two distinct scenarios within this framework: one in which the ancilla is reset to its initial coherent state after each interaction (the traditional collision model), and another where the ancilla is not reset but its state is simply carried over to the next interaction, which we dub the repeated interaction model. In both scenarios, we ensure that the system-ancilla correlations are discarded between steps. We also demonstrate how varying the ancilla-system interaction patterns enables selective generation of entanglement between different qubit pairs, including non-neighbouring nodes that do not directly interact. The scheme is analyzed in networks up to three qubits under both collision and repeated interaction dynamics, revealing the genaration of maximally entangled bell pairs even in configurations where the interacting ancilla couples to only a single node. Our results provide a systematic and physically implementable route to entanglement distribution, offering potential applications in quantum communication, metrology and modular quantum computing.