Original title: A proposal for a hybrid free-space optical quantum communication network with hexagonal boron nitride-based single photon sources
Julien Chénedé, Mostafa Abasifard, Tjorben Matthes, Aslı Çakan +1 · September 2026
Sending secure quantum signals from space usually fails during the day because bright sunlight drowns out single light particles, called photons. To solve this, researchers designed a plan using hexagonal boron nitride, a material that shoots out high-purity single photons even at room temperature. They created a pathway to tune these space-ready emitters to 854 nm. This matches a solar dip where atmospheric sunlight is naturally dimmer, allowing daylight satellite connections. This wavelength also aligns with the 850 nm fiber-optic window. As a result, one ground station can catch the satellite beams and route them through standard fiber cables to multiple users. This setup allows continuous day-and-night quantum networking, lowers setup costs, and delivers high data rates.
You try to shout a secret number across a crowded football stadium, but the crowd noise drowns you out. If you pick a moment when the crowd is quiet, your shout carries clearly. In this paper, the stadium is the daytime sky, the crowd noise is sunlight, and the quiet moment is the Fraunhofer line wavelength where sunlight is weak—so the secret number (the quantum key) gets through without interference.
Current quantum key distribution (QKD) systems struggle in daylight because background light drowns out single-photon signals. This concept uses hexagonal boron nitride emitters tuned to a specific color where the sun's light is naturally dim, enabling secure communication during the day. It also mixes satellite links with fiber optics to connect last-mile users cheaply, moving the quantum internet closer to practical use.
The abstract describes a proposed pathway, not an implemented system. It does not provide experimental data or performance metrics such as key rates or error rates. Developing hBN emitters precisely at 854 nm with sufficient brightness and purity is not yet demonstrated in this work. The concepts of continuous operation and hybrid links remain theoretical at this stage.
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A proposal for a hybrid free-space optical quantum communication network with hexagonal boron nitride-based single photon sources — Julien Chénedé, Mostafa Abasifard, Tjorben Matthes et al.
Abstract licence: CC0
Explanation generated by Synthesis from the abstract — it is not the original paper. This is a preprint, so it hasn't necessarily been peer reviewed.