Abstract
Concerted efforts are underway to establish an infrastructure for a global quantum Internet to realise a spectrum of quantum technologies. This will enable more precise sensors, secure communications, and faster data processing. Quantum communications are a front-runner with quantum networks already implemented in several metropolitan areas. A number of recent proposals have modelled the use of space segments to overcome range limitations of purely terrestrial networks. Rapid progress in the design of quantum devices have enabled their deployment in space for in-orbit demonstrations. We review developments in this emerging area of space-based quantum technologies and provide a roadmap of key milestones towards a complete, global quantum networked landscape. Small satellites hold increasing promise to provide a cost effective coverage required to realise the quantum Internet. The state of art in small satellite missions is reviewed and the most current in-field demonstrations of quantum cryptography are collated. The important challenges in space quantum technologies that must be overcome and recent efforts to mitigate their effects are summarised. A perspective on future developments that would improve the performance of space quantum communications is included. The authors conclude with a discussion on fundamental physics experiments that could take advantage of a global, space-based quantum network.
Highlights
The second quantum revolution promises a paradigm shift in quantum technologies that will deliver new capabilities, and performance enhancements in security, accuracy and precision [1]
We focus on capturing the fast progress in the emerging area of space‐based quantum communications
We briefly summarise a selection of small satellite mission proposals, development and upcoming launches in the remainder of this section
Summary
The second quantum revolution promises a paradigm shift in quantum technologies that will deliver new capabilities, and performance enhancements in security, accuracy and precision [1]. The working principles that permit these performance improvements are deep‐rooted phenomena in quantum mechanics, such as entanglement [2], teleportation [3,4,5], the Heisenberg uncertainty principle [6] and the no‐cloning theorem [7]. These effects illustrate a key departure from classical physics and are at the heart of delivering improvements to technologies that underpin modern society. Quantum theory governs how information is instantiated and processed in the configuration of matter and energy. This realisation led to an explosion in the development of quantum technologies. The race to develop mature quantum technologies has become a discipline in its own right with major renewed international efforts, both governmental and commercial
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