Yuval Reches | Searcharxiv

arXiv2026

Free-space and Satellite-Based Quantum Communication: Principles, Implementations, and Challenges

Satellite-based quantum communications represent a critical advancement in the pursuit of secure, global-scale quantum networks. Leveraging the principles of quantum mechanics, these systems offer unparalleled security through Quantum Key Distribution (QKD) and other quantum communication protocols. This review provides a comprehensive overview of the current state of satellite-based quantum communications, focusing on the evolution from terrestrial to space-based systems. We explore the distinct advantages and challenges of discrete-variable (DV) and continuous-variable (CV) quantum communication technologies in the context of satellite deployments. The paper also discusses key milestones such as the successful implementation of quantum communication via the Micius satellite and outlines the primary challenges, including atmospheric turbulence and the development of quantum repeaters, that must be addressed to achieve a global quantum internet. This review aims to consolidate recent advancements in the field, providing insights and perspectives on the future directions and potential innovations that will drive the continued evolution of satellite-based quantum communications.

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arXiv2024

Efficient Robust Spontaneous Parametric Down-Conversion via Detuning Modulated Composite Segments Designs

Spontaneous Parametric Down Conversion (SPDC) holds a pivotal role in quantum physics, facilitating the creation of entangled photon pairs, heralded single photons and squeezed light, critical resources for many applications in quantum technologies. However, their production is susceptible to physical variations, posing limitations on their robust utility. To overcome these limitations, this work introduces a method to significantly enhance the reliability of entangled photon pair generation. This approach involves introducing a composite design scheme to the SPDC process. The design is based on the development of a theoretical composite segments framework for SU(1,1), offering increased error resilience and robustness of the process. The practical application is experimentally demonstrated by modulating the nonlinear coefficient of a KTP crystal for degenerate 532 nm to 1064 nm conversion, resulting in an effective sevenfold improvement in stability of photon-pair generation and coincidence rate against temperature fluctuations compared to conventional quasi-phase-matching techniques. Furthermore, the presented concept is applicable to other physical systems that exhibit SU(1,1) dynamics. This methodology can create a leap forward in quantum technologies by significantly enhancing stability and error tolerance, thus paving the way for a new generation of entangled photon sources, holding promise for quantum information processing, communication, and precision measurement applications.

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