Experimental Single-Photon Transmission from Satellite to Earth

Satellite-based quantum steering under the influence of spacetime curvature of the Earth

Spacetime curvature of the Earth deforms wavepackets of photons sent from the Earth to satellites, thus influencing the quantum state of light. We show that Gaussian steering of photon pairs, which are initially prepared in a two-mode squeezed state, is affected by the curved spacetime background of the Earth. We demonstrate that quantum steerability of the state increases for a specific range of height $h$ and then gradually approaches a finite value with further increasing height of the satellite's orbit. Comparing with the peak frequency parameter, the Gaussian steering changes more for dif…

利用空间多样性提升地球到卫星的量子-经典通信

Exploiting Spatial Diversity in Earth-to-Satellite Quantum-Classical Communications

本研究首次探讨了利用空间多样性缓解地球到卫星量子通信中衰减问题，通过理论分析和数值模拟证明了多地面站与卫星多接收孔径组合能提升纠缠分布效率。

Temporal Modes of Light in Satellite-to-Earth Quantum Communications

The photonic Temporal Mode (TM) represents a possible candidate for the delivery of viable multidimensional quantum communications. However, relative to other multidimensional quantum information carriers such as the Orbital Angular Momentum (OAM), the TM has received less attention. Moreover, in the context of the emerging quantum internet and satellite-based quantum communications, the TM has received no attention. In this work, we remedy this situation by considering the traversal through the satellite-to-Earth channel of single photons encoded in TM space. Our results indicate that for ant…

面向星地通道的量子与后量子组合安全

Combined Quantum and Post-Quantum Security for Earth-Satellite Channels

本研究开发了一个实时原型QKD系统，首次部署BBM92协议，通过结合AES后量子安全与基于纠缠的QKD量子安全，确保在密钥率较低或单一加密被攻破时，星地通信仍具备抵御未来量子计算机的先进安全性。

Photonic Engineering for CV-QKD over Earth-Satellite Channels

Quantum Key Distribution (QKD) via satellite offers up the possibility of unconditionally secure communications on a global scale. Increasing the secret key rate in such systems, via photonic engineering at the source, is a topic of much ongoing research. In this work we investigate the use of photon-added states and photon-subtracted states, derived from two mode squeezed vacuum states, as examples of such photonic engineering. Specifically, we determine which engineered-photonic state provides for better QKD performance when implemented over channels connecting terrestrial receivers with Low…

Experimental verification of the feasibility of a quantum channel between Space and Earth

Extending quantum communication to Space environments would enable to perform fundamental experiments on quantum physics as well as applications of quantum information at planetary and interplanetary scales. Here, we report the first experimental implementation of a scheme for single-photon exchange between a satellite and an Earth-based station. We built an experiment that mimics a single photon source on a satellite, exploiting the telescope at the Matera Laser Ranging Observatory of the Italian Space Agency to detect the transmitted photons. Weak laser pulses, emitted by the ground-based st…

星地量子通信中用于相位估计的机器学习

Machine Learning for Phase Estimation in Satellite-to-Earth Quantum Communication

针对星地CV-QKD网络中信号相位误差估计的速度与准确度需求，提出基于低复杂度长短期记忆神经网络架构的估计方法，在不显著牺牲准确度的前提下显著提升了系统的实时性能。

Influence of relativistic effects on satellite-based clock synchronization

Clock synchronization between the ground and satellites is a fundamental issue in future quantum telecommunication, navigation, and global positioning systems. Here, we propose a scheme of near-Earth orbit satellite-based quantum clock synchronization with atmospheric dispersion cancellation by taking into account the spacetime background of the Earth. Two frequency entangled pulses are employed to synchronize two clocks, one at a ground station and the other at a satellite. The time discrepancy of the two clocks is introduced into the pulses by moving mirrors and is extracted by measuring the…