Portable ground stations for space-to-ground quantum key distribution

Abstract

Quantum key distribution (QKD) uses the fundamental principles of quantum mechanics to share unconditionally secure keys between distant users. Previous works based on the quantum science satellite "Micius" have initially demonstrated the feasibility of a global QKD network. However, the practical applications of space-based QKD still face many technical problems, such as the huge size and weight of ground stations required to receive quantum signals. Here, we report space-to-ground QKD demonstrations based on portable receiving ground stations. The weight of the portable ground station is less than 100 kg, the space required is less than 1 m 3 and the installation time requires no more than 12 hours, all of the weight, required space and deployment time are about two orders of magnitude lower than those for the previous systems. Moreover, the equipment is easy to handle and can be placed on the roof of buildings in a metropolis. Secure keys have been successfully generated from the "Micius" satellite to these portable ground stations at six different places in China, and an average final secure key length is around 50 kb can be obtained during one passage. Our results pave the way for, and greatly accelerate the practical application of, space-based QKD.

Polarization compensation method based on the wave plate group in phase mismatch for free-space quantum key distribution

“…In free-space QKD, a basis vector deviation between the transmitter and the receiver is inevitable [11,21,22]. Generally, the receiver is equipped with a nearly perfect 1/2 wave plate for basis vector correction [22,23], which can help to achieve high-fidelity transmission of quantum keys from the transmitter to the receiver.…”

Application and Development of QKD-Based Quantum Secure Communication

“…To take advantage of the mobility and flexibility of satellite-based QKD, a portable ground station is essential supporting equipment. Portable ground stations weighing less than 100 kg, requiring less than 1 m 3 of space, and taking no more than 12 h to install have been successfully developed and could be deployed on the rooftops of urban buildings to complete space-to-ground QKD experiments with Micius [ 88 ]. Satellite-based QKD is one of the most important use cases to fully utilize the advantages of QKD, which could provide quantum key services for remote locations or moving objects that do not have fiber accessibility.…”

Optical transmitter for time-bin encoding Quantum Key Distribution

“…Since then, many protocols, techniques and emerging technologies have contributed to bolster this rapidly expanding field. Preferred channels for these quantum communications protocols are optical fibers in the near infrared spectral region [4][5][6][7] and, most recently, open space links between ground stations and low earth orbit satellites [8][9][10]. Ground based QKD protocols have evolved to simpler and more efficient schemes combined with robust security that feature symbol rates in the order range of the GHz [11][12][13][14][15][16], and record length transmission links exceeding 400 km of single mode fibers [17] for prepare-and-measure protocols, 800 km for the novel twin-field protocols [18] and 1000 km for entanglement-based protocols [19] .…”