A resource-efficient and noise-robust entanglement witness based on the swap test

Fuente: arXiv
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Main Authors: Guaraldo, Sebastiano, Mazzucchi, Sonia, Baldazzi, Alessio, Azzini, Stefano, Pavesi, Lorenzo
Format: Preprint
Published: 2025
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author Guaraldo, Sebastiano
Mazzucchi, Sonia
Baldazzi, Alessio
Azzini, Stefano
Pavesi, Lorenzo
author_facet Guaraldo, Sebastiano
Mazzucchi, Sonia
Baldazzi, Alessio
Azzini, Stefano
Pavesi, Lorenzo
contents Quantum entanglement is an essential resource for quantum technologies, and the controlled swap test provides a versatile tool for its detection and quantification. Here, we propose a SWAP-based entanglement witness that applies to arbitrary two-qubit states - both pure and mixed - and provides a lower bound on the concurrence. The method is resource-efficient, robust to noise, and platform-independent. As an example, we validate the approach on a room-temperature photonic chip, where the swap test is carried out using only linear and well-established integrated optical components. The robustness of the method against photonic-hardware noise is also analysed. Our results establish a simple and reliable tool for entanglement witnessing.
format Preprint
id arxiv_https___arxiv_org_abs_2512_20235
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A resource-efficient and noise-robust entanglement witness based on the swap test
Guaraldo, Sebastiano
Mazzucchi, Sonia
Baldazzi, Alessio
Azzini, Stefano
Pavesi, Lorenzo
Quantum Physics
Quantum entanglement is an essential resource for quantum technologies, and the controlled swap test provides a versatile tool for its detection and quantification. Here, we propose a SWAP-based entanglement witness that applies to arbitrary two-qubit states - both pure and mixed - and provides a lower bound on the concurrence. The method is resource-efficient, robust to noise, and platform-independent. As an example, we validate the approach on a room-temperature photonic chip, where the swap test is carried out using only linear and well-established integrated optical components. The robustness of the method against photonic-hardware noise is also analysed. Our results establish a simple and reliable tool for entanglement witnessing.
title A resource-efficient and noise-robust entanglement witness based on the swap test
topic Quantum Physics
url https://arxiv.org/abs/2512.20235