26th Australian Institute of Physics Congress and the Australian and New Zealand Conference on Optics and Photonics

Certifying high-dimensional entanglement via particle exchange symmetry

Not scheduled

20m

Belinda Hutchinson Building (The University of Sydney )

Contributed Oral AIP | Quantum Science and Technology (QST)

Speaker

Jayden Webster (Quantum and Advanced Technologies Research Institute, Griffith University, Yuggera Country, Brisbane, QLD 4111, Australia)

Description

Photons have proven themselves to be an excellent choice for carrying quantum information. Storing information in the arrival time of photons, i.e. time-bin encoding, naturally enables the creation of high-dimensional states that are information dense and robust against noise. By coupling high-dimension time-bin encoding with entanglement, we can extend the application of these states into the realm of classically intractable quantum information tasks. However, certifying entanglement in high dimensions is a significant challenge. Traditional methods require either a number of measurements and/or outcomes that scale with the certified dimension, or strict assumptions on the nature of the probed state (or sometimes both), which, in turn, increase the complexity or compromise on the generality of the approach.

Our work overcomes these issues [1]. Using a simple linear optical scheme, we alter the particle exchange symmetry of an unknown, high-dimensional time-bin-entangled state. By then utilizing the sensitivity of Hong-Ou-Mandel interference to state symmetry, in combination with a novel entanglement witness, we extract a lower bound on the entanglement dimension of this state. In an adversarial scenario, that is, one with no assumptions about our state, we certify a non-trivial three dimensions of entanglement. As we include further physically justified assumptions, our certification improves to 12 dimensions of entanglement. Significantly, these certified entanglement dimensions are obtained using only two dichotomic measurements, without any assumptions on the probed state, while remaining independent of the detector temporal resolution. Therefore, our approach represents a powerful tool for harnessing high-dimensional time-bin-entangled quantum states, paving the way for scalable time-bin-based technologies.

[1] Jayden Webster et al. Revealing high-dimensional entanglement through symmetry. 2026. arXiv: 2606.23817 [quant-ph]. URL: https://arxiv.org/abs/2606.23817.