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arXiv · 2507.08102

Photonic quantum information with time-bins: Principles and applications

Ashutosh Singh·Anuj Sethia·Leili Esmaeilifar·Raju Valivarthi·Neil Sinclair·Maria Spiropulu·Daniel Oblak
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Abstract

Long-range quantum communication, distributed quantum computing, and sensing applications require robust and reliable ways to encode transmitted quantum information. In this context, time-bin encoding has emerged as a promising candidate due to its resilience to mechanical and thermal perturbations, depolarization from refractive index changes, and birefringence in fiber optic media. Time-bin quantum bits (qubits) can be produced in various ways, and each implementation calls for different considerations regarding design parameters, component compatibility (optical, electrical, electro-optical), and measurement procedures. Here, we provide a comprehensive overview of experimental methods for preparing and characterizing time-bin qubits (TBQs) for quantum communication protocols, with an assessment of their advantages and limitations. We discuss challenges in transmitting TBQs over optical fibers and free-space channels, and methods to overcome them. We also analyze the selection of key time-bin parameters and component requirements across experiments. This leads us to explore the preparation and characterization of time-bin entanglement and examine requirements for interference of time-bins from separate sources. Further, we cover preparation and characterization techniques for high-dimensional time-bin states, namely qudits, and the generation of time-bin entangled qudit pairs. We review time-energy entanglement and key experimental realizations. Finally, we present notable applications of time-bin encoded quantum states, from quantum communication protocols to photonic quantum computation. This work serves as an accessible introduction and a comprehensive review of recent developments.

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Ashutosh Singh, Anuj Sethia, Leili Esmaeilifar, Raju Valivarthi, Neil Sinclair, Maria Spiropulu, Daniel Oblak. 2026-07-02. Photonic quantum information with time-bins: Principles and applications. https://doi.org/10.1016/j.physrep.2026.06.005

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