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Main Authors: Guo, Yu, Chowdhury, Arya, Tiwari, Pranay, Chin, Jia Boon, Banerji, Anindya, Ling, Alexander
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2605.25609
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author Guo, Yu
Chowdhury, Arya
Tiwari, Pranay
Chin, Jia Boon
Banerji, Anindya
Ling, Alexander
author_facet Guo, Yu
Chowdhury, Arya
Tiwari, Pranay
Chin, Jia Boon
Banerji, Anindya
Ling, Alexander
contents Photonic hyperentanglement enables increased information capacity and enhanced functionality for quantum communication and networking. However, synchronization of hyperentangled photon pairs requires maintaining correlations simultaneously across multiple degrees of freedom (DOFs). The preservation of polarization and energy-time entanglement in hyperentangled photon pairs is demonstrated using a free-space optical delay line based on nested Herriott cells. After a delay of 647 ns, a two-photon interference visibility of 93.9(3)% is observed in the energy-time DOF, while a CHSH parameter of 2.758(5) is obtained in the polarization DOF. These results confirm that entanglement correlations in both DOFs are preserved after propagation through the delay line. They demonstrate that free-space optical delay lines are compatible with complex photonic quantum states and provide a promising route toward delay-based memories for synchronization and multiplexing in quantum networks.
format Preprint
id arxiv_https___arxiv_org_abs_2605_25609
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle High fidelity preservation of photonic hyperentanglement in a free-space optical delay line
Guo, Yu
Chowdhury, Arya
Tiwari, Pranay
Chin, Jia Boon
Banerji, Anindya
Ling, Alexander
Quantum Physics
Photonic hyperentanglement enables increased information capacity and enhanced functionality for quantum communication and networking. However, synchronization of hyperentangled photon pairs requires maintaining correlations simultaneously across multiple degrees of freedom (DOFs). The preservation of polarization and energy-time entanglement in hyperentangled photon pairs is demonstrated using a free-space optical delay line based on nested Herriott cells. After a delay of 647 ns, a two-photon interference visibility of 93.9(3)% is observed in the energy-time DOF, while a CHSH parameter of 2.758(5) is obtained in the polarization DOF. These results confirm that entanglement correlations in both DOFs are preserved after propagation through the delay line. They demonstrate that free-space optical delay lines are compatible with complex photonic quantum states and provide a promising route toward delay-based memories for synchronization and multiplexing in quantum networks.
title High fidelity preservation of photonic hyperentanglement in a free-space optical delay line
topic Quantum Physics
url https://arxiv.org/abs/2605.25609