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arXiv · 2407.04048

Time-bin entangled Bell state generation and tomography on thin-film lithium niobate

Giovanni Finco·Filippo Miserocchi·Andreas Maeder·Jost Kellner·Alessandra Sabatti·Robert J. Chapman·Rachel Grange
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Abstract

Optical quantum communication technologies are making the prospect of unconditionally secure and efficient information transfer a reality. The possibility of generating and reliably detecting quantum states of light, with the further need of increasing the private data-rate is where most research efforts are focusing. The physical concept of entanglement is a solution guaranteeing the highest degree of security in device-independent schemes, yet its implementation and preservation over long communication links is hard to achieve. Lithium niobate-on-insulator has emerged as a revolutionising platform for high-speed classical telecommunication and is equally suited for quantum information applications owing to the large second-order nonlinearities that can efficiently produce entangled photon pairs. In this work, we generate maximally entangled quantum states in the time-bin basis using lithium niobate-on-insulator photonics at the fibre optics telecommunication wavelength, and reconstruct the density matrix by quantum tomography on a single photonic integrated circuit. We use on-chip periodically-poled lithium niobate as source of entangled qubits with a brightness of 242 MHz/mW and perform quantum tomography with a fidelity of 91.9+-1.0 %. Our results, combined with the established large electro-optic bandwidth of lithium niobate, showcase the platform as perfect candidate to realise fibre-coupled, high-speed time-bin quantum communication modules that exploit entanglement to achieve information security.

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Giovanni Finco, Filippo Miserocchi, Andreas Maeder, Jost Kellner, Alessandra Sabatti, Robert J. Chapman, Rachel Grange. 2024-07-04. Time-bin entangled Bell state generation and tomography on thin-film lithium niobate. https://arxiv.org/abs/2407.04048

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