Entangling independent particles by path identity

TL;DR

This paper demonstrates that independent particles can be entangled without direct interaction or prior entanglement, by exploiting the indistinguishability of their origins, challenging traditional views and potentially simplifying quantum network resources.

Contribution

It introduces a novel method to entangle independent particles through path identity, bypassing the need for local interactions or Bell-state measurements.

Findings

Entanglement achieved without prior shared entanglement.

Reduces resource requirements for quantum networks.

Challenges traditional entanglement generation assumptions.

Abstract

Quantum entanglement -- correlations of particles that are stronger than any classical analogue -- is the basis for research on the foundations of quantum mechanics and for practical applications such as quantum networks. Traditionally, entanglement is achieved through local interactions or via entanglement swapping, where entanglement at a distance is generated through previously established entanglement and Bell-state measurements. However, the precise requirements enabling the generation of quantum entanglement without traditional local interactions remain less explored. Here we demonstrate that independent particles can be entangled without the need for direct interaction, prior established entanglement, or Bell-state measurements, by exploiting the indistinguishability of the origins of photon pairs. Our demonstrations challenge the long-standing belief that the prior generation and measurement of entanglement are necessary prerequisites for generating entanglement between independent particles that do not share a common past. In addition to its foundational interest, we show that this technique might lower the resource requirements in quantum networks, by reducing the complexity of photon sources and the overhead photon numbers.