This paper looks at the impacts that emerging quantum technologies might have on defence. Some of the technologies are relatively well known; for example, there are many popular articles on quantum computing and its possible implications. There’s a growing technical literature on quantum radar, and there’s been some breathless recent reporting about it negating the advantages of stealth technology.

You can’t buy a quantum radar or computer yet, but there are practical applications of other new quantum technologies. China has announced that it has a working quantum communication satellite system. And it’s worth noting that what we’re talking about here is really the latest generation of quantum systems. Previous innovations based on quantum physics have already had a major impact on both military and civilian technologies. The invention in 1947 of the transistor, which relies on intrinsic quantum effects for its operation, led to the microelectronics that are now ubiquitous in communication, computing, sensor and navigation systems. The development of the atomic clock in the 1950s enabled high-precision timing in the laboratory. After the development of devices that could function in less benign environments, like those experienced in satellite launches, they were employed in systems such as GPS to generate positional information. The ‘revolution in military affairs’ that came to public attention so dramatically in the 1991 Gulf War had quantum technologies at its heart.

Note that there are multiple steps in turning a technological idea into a system that’s sufficiently robust for widespread use. The typical path is from idea, to ‘proof of concept’, to an up-scaled but still laboratory-based device. While laboratory devices sometimes have real-world applications, such as the primitive computers used to break codes in World War II, for widespread use the system must be productionised, including whatever degree of ‘ruggedisation’ is needed for practical applications. This paper assesses the status of what we think are the four most significant emerging quantum technologies: computing, communications, radar and remote sensing.