I remember learning at university about quantum entanglement and Erwin Schrödinger’s famous thought experiment relating to the hypothetical cat in a box that is considered to be dead and alive at the same time. Quantum key distribution relies on quantum entanglement and promises unconditional security, which is considered as the Holy Grail of communication security. Unlike classical key distribution, the presence of an eavesdropper can be detected by two communicating users. Experimental quantum key distribution has been performed over distances in the order of 100 km in standard telecom fibres as well as in free space.

There seem to be many potential applications of quantum key distribution, including in space-related technologies. According to the quantum technologies and space report prepared by the EPO and the European Space Policy Institute (ESPI) in collaboration with the European Space Agency (ESA), quantum key distribution is currently the leading application in space-related quantum technologies. More than 77% of the identified space-related quantum technology patent filings relate to this application, which largely accounts for an overall growth in space-related quantum technology patent filings between 2015 and 2020.

According to the report, there is a clear sense of urgency to develop new secure communication methods, in the wake of technological advances in quantum computing. The patent data presented in the report seems to confirm that this urgency is translating into a noticeable wave of new inventions in space-related quantum key distribution. No doubt satellite quantum key distribution links will play an important role in secure communication networks in the future.

In addition to quantum key distribution, the report identifies two further key space-related quantum technologies, namely cold atom clocks and cold atom interferometers. New-generation cold atom clocks allow for improved positioning, navigation and timing applications, while cold atom interferometers can be used in Earth sensing and observation technologies.

The number of patent families relating to these three space-related quantum technologies has been growing more than fourfold between 2015 and 2020. This highlights that space-related quantum technologies can be considered as a rapidly emerging technology with an increasing number of inventions, therefore gaining in commercial and strategical importance.

Space applications of quantum technology are a fast-growing domain, with patent filings increasing by more than 400% over the last five years.