Space–ground QKD network based on a compact payload and medium-inclination orbit

Abstract

Significant progress has been made in satellite-based quantum key distribution (QKD), and urgent follow-up work is to explore the optimal solution for building practical quantum constellations. Here, we demonstrate successful QKD based on the compact terminal on the Tiangong-2 Space Lab and construct a space–ground quantum network among four ground stations. The medium-inclination orbit of Tiangong-2 Space Lab can obtain multiple available passes for the same ground station in one night, increasing the key generation amount directly. Further analysis results show that the medium-inclination orbit and Sun-synchronous orbit can form good complementarity in future quantum constellations. As a comprehensive demonstration, this work takes a step toward cost-effective quantum satellites and provides a perspective for satellite constellation construction with different orbit types.

State-dependent misalignment and turbulence effects on high-dimensional quantum key distribution with orbital angular momentum

“…L pe (ρ) = L pe (∆x, ∆y) = ˆA I l (x + ∆x, y + ∆y, z) dxdy (8) where (∆x) 2 + (∆y) 2 = ρ 2 . Replace the telescope area A with a square aperture of area π (D R /2) 2 .…”

“…Based on quantum mechanics, QKD could provide information-theoretic approach against an eavesdropper during key distribution tasks [1][2][3]. Currently, along with the breakthrough of fiber-based [4][5][6] and satellite-based [7,8] quantum communication, building and operating a high-efficient and flexible quantum internet has become a grand vision attracting global attention [9,10]. However, most of these achievements are based on encoding information with two-dimensional quantum systems such as polarization and phase of photons.…”

Evaluation of Quantum Key Distribution for Secure Satellite-integrated IoT Networks

“…Tiangong-2 Space Lab is a Chinese space station orbiting in a LEO at medium inclination. It has been used as a testbed for a trusted relay for a QKD experiment, achieving a sifted key generation rate of 1.33 Mb per day under best-case conditions (Li et al, 2022). This experiment showed that by combining satellites in sun synchronous orbit (SSO) and medium inclination orbit (MIO), a higher overall key rate per day can be achieved due to the multi-pass benefit of MIOs.…”

“…More recently, there have been QKD experiments performed on actual space-ground optical downlinks from LEO, most notably using the satellite Micius under the auspices of the Chinese QUESS program (Liao et al, 2017) and Tiangong-2 Space Lab (Li et al, 2022). These experiments show that whilst their key generation rate is still too miniscule to be useful in an IoT backhaul application, the concept of satellite-based QKD is at least feasible and now needs only to be scaled up.…”

Quantum walk-based protocol for secure communication between any two directly connected nodes on a network

“…One of the most accessible technologies in this regard are the quantum key distribution (QKD) protocols to ensure secure communication [15][16][17]. The QKD networks have been deployed in large metropolitan settings [18][19][20][21][22], and have also been operationally demonstrated in networks connecting ground stations using satellites as trusted nodes [23][24][25][26][27], highlighting the utility of this approach.…”