Space-to-Ground Quantum Key Distribution Using a Small-Sized Payload on Tiangong-2 Space Lab

【摘要】 Quantum technology establishes a foundation for secure communication via quantum key distribution(QKD). In the last two decades, the rapid development of QKD makes a global quantum communication network feasible. In order to construct this network, it is economical to consider small-sized and low-cost QKD payloads, which can be assembled on satellites with different sizes, such as space stations. Here we report an experimental demonstration of space-to-ground QKD using a small-sized payload, from Tiangong-2 space lab to Nanshan ground station. The 57.9-kg payload integrates a tracking system, a QKD transmitter along with modules for synchronization, and a laser communication transmitter. In the space lab,a 50 MHz vacuum+weak decoy-state optical source is sent through a reflective telescope with an aperture of 200 mm. On the ground station, a telescope with an aperture of 1200 mm collects the signal photons. A stable and high-transmittance communication channel is set up with a high-precision bidirectional tracking system, a polarization compensation module, and a synchronization system.When the quantum link is successfully established,we obtain a key rate over 100 bps with a communication distance up to 719 km. Together with our recent development of QKD in daylight,the present demonstration paves the way towards a practical satellite-constellation-based global quantum secure network with small-sized QKD payloads.更多还原

【Abstract】 Quantum technology establishes a foundation for secure communication via quantum key distribution(QKD). In the last two decades, the rapid development of QKD makes a global quantum communication network feasible. In order to construct this network, it is economical to consider small-sized and low-cost QKD payloads, which can be assembled on satellites with different sizes, such as space stations. Here we report an experimental demonstration of space-to-ground QKD using a small-sized payload, from Tiangong-2 space lab to Nanshan ground station. The 57.9-kg payload integrates a tracking system, a QKD transmitter along with modules for synchronization, and a laser communication transmitter. In the space lab,a 50 MHz vacuum+weak decoy-state optical source is sent through a reflective telescope with an aperture of 200 mm. On the ground station, a telescope with an aperture of 1200 mm collects the signal photons. A stable and high-transmittance communication channel is set up with a high-precision bidirectional tracking system, a polarization compensation module, and a synchronization system.When the quantum link is successfully established,we obtain a key rate over 100 bps with a communication distance up to 719 km. Together with our recent development of QKD in daylight,the present demonstration paves the way towards a practical satellite-constellation-based global quantum secure network with small-sized QKD payloads.更多还原