Chinese work on radars and quantum communications – especially with the launch of the Micius satellite – has for some time drawn attention to technologies that are still only emerging, but which some do not hesitate to say have an equally disruptive effect on strength systems as the advent of information technology.
Quantum-related technologies are those that pertain to the infinitely small. The field is not new in this area, and some authors see in the development of technologies related to nuclear or laser a “first quantum revolution”. The “second quantum revolution” relates to ” manipulation and control of individual quantum systems (such as atoms, ions, electrons, photons, molecules or various quasi-particles) to reach the standard quantum limit, ie. the measurement accuracy limit on quantum scales (1) “.
When it comes to control on these scales, the logic goes beyond designing nanomaterials by, for example, assembling atoms. Rather, it involves playing on the properties of the particles to exploit a physics that breaks with classical physics. The field is all the more complex because quantum physics itself is only in its infancy, many of its principles have not yet been fully explained, and it is possible that a certain number have not even been discovered yet. However, several technological applications are possible depending on the current knowledge.
As such, quantum technologies are not specifically military and have dual potential. In the same way, apart from imagining a weapon that creates the decoction of a target on a (sub) atomic scale, the applications that are currently being considered relate first and foremost to the – sometimes radical – development of existing technologies with performance gains that are not comparable to the progress made. long. A priori, three areas are affected by quantum technologies: communication and their encryption; detection technologies (radar or sonar); computer-based systems.
The operating principle of quantum communication or detection systems is based on quantum entanglement. Specifically, to simplify, this consists of “splitting” photons (by caricature, in the same way as cellular mitosis). They will remain connected because of their quantum properties, despite the distances. China has thus launched Micius (Mozi), the first platform to enable quantum transmissions, ensuring an unprecedented degree of communication security. The satellite was launched in 2016 and in 2017 allowed a transmission of 7,400 km between Beijing and Vienna by distributing cryptographic keys. By 2020, Micius’s entangled photon streams between two terminals transmitted 1,200 km apart, and functioned effectively as a communications satellite.
Quantum entanglement has the advantage that if a stream of photons – typically encoded to convey a message – is intercepted, the “control” photons will respond automatically. Transmission security is therefore guaranteed at all times, and another encryption key can then be distributed. In addition, the photons themselves are transmitted in a laser-borne flux, and intercepting the beam in such a way that it captures and decodes the flux, is in itself dangerous. However, there is no shortage of obstacles, starting with the classic problem of laser diffraction in the atmosphere. But Micius already represents in itself a real advance, while the principles of quantum cryptology were already tested in the early 2000s (2). China intends in the long run to have 20 satellites of the same type and thus create a quantum communications network in proper form.
A detection revolution?
The principle of quantum entanglement can also be used in detection systems. Thus, after cleavage, photons transmitted by microwaves into the atmosphere or ocean could play the role of a sonar “ping” or a radar wave. The study of the “control photon”, not sent, then makes it possible to perform detections and characterize them – at least in theory. Detection on large amounts of space involves repeating the process a large number of times. The advantage of using subatomic particles seems so obvious: no matter what material is affected, it will affect the behavior of the “control” photons left in the analysis center. The system therefore has a very real potential in the fight against stealth.
It is then left to determine the reaction schemes to interpret this behavior, which requires phenomenal computing power, which could be made possible by the quantum calculation itself under development (see box). De facto, the experiments currently being carried out are within an R & T framework, and operationalization is still a long way off. If this work ends up being a success, other breakthroughs must be expected in other detection areas, especially in submarine warfare. Here, too, the rise of computer power offers treatment options that will be more than useful – given that in the current state they may not be sufficient. Moreover, the obstacles are not small. So far, quantum entanglement in a radar detection sequence has only been confirmed at a distance of 100 km in the atmosphere, but China was already working in 2016 on 1,000 km experiments.
In addition, applications from medicine can also pose a threat. SQUIDS (Superconducting Quantum Interference Devices) are already used to measure small variations of the magnetic field in the brain. If they are placed on a sufficiently large number of vectors, they can then be used as magnetometers / magnetic anomaly detectors. Historically, the latter are used mainly for the detection of submarines, but their range is low – they must practically exceed the target – and it is possible to escape them in case of deep immersion. But squid could also be used in the sea, and so far two barriers to their use have prevented any operationalization. The first is the need to cool them with large amounts of liquid nitrogen. In the meantime, however, microcooling systems have emerged. Another barrier is the need to multiply the vectors to offer the widest possible “view”. However, developments in drone systems, whether under water, air or surface, could provide a solution.
Other detection applications are also envisaged, this time in the short term: miniaturized RF (radio frequency) antennas for reception, but also 3D imaging systems, which could be useful for mapping the seabed, but also for underground facilities. The proposed systems would allow detection even in foggy weather or in dusty areas or even in complex environments, such as jungles. The recording of images by photoacoustic process could also be much more accurate. In many cases, the implemented technologies require mastery of those related to lasers. The field of detection and classification of chemical agents is also discussed.
The exploitation of the characteristics of quantum physics from the 1990s opened the way for research into computational systems that would make it possible to revolutionize data processing. To sum up roughly, where a classical computer works in the form of bits – 0 or 1 – a quantum computer works in qbits (quantum bits) with an infinity of potential values. The memory is therefore largely larger, but like Schrödinger’s cat both dead and alive, the exact value is known only at the moment of measurement. The main application of these systems is in massive parallel computing that multiplies the number of operations: the calculation is performed not sequentially, but holistically. Yet a calculator is not yet a computer – the term quantum computer is a misleading term. In fact, it is not (yet) a question of software programming. The main obstacle to the operationalization of these systems is the number of qbits (with the risk of decoherence: too many subatomic actions end up losing the quantum properties) and the necessary physical supports. Google produced a 53 qbits calculator in 2019. IBM intends to have 1,121 qbits by 2023. We are therefore still a long way from a “quantum chip” that can be integrated into a computer even when working actively, especially in the US and China states .