What are quantum technologies?
The name comes from breaking down anything - light, matter and energy – into its smallest possible unit, a unit called a “quantum” (plural, quanta). At this scale, all objects stop behaving in the ways we’re used to, the ways classical physics describes them. Instead, quanta behave in ways that are difficult to comprehend. They often behave as if they’re two things at once, for example, a photon (a quantum of light) behaves as if it is both a particle and a wave.
This results in quanta having two properties which have huge potential to transform technology. The first is that, at this scale, objects can be in two states or places at the same time (known as superposition); the second is that two quanta can affect each other even though they are far apart (known as entanglement).
Both superposition and entanglement have the potential of transforming many aspects of our business in the future.
Quantum computing and decrypting data
Superposition and entanglement offer tremendous possibilities for computing. Whereas classical computing uses units – ‘bits’ – which are either a “0” or a “1”, in a quantum computer, the quantum bits – ‘qubits’ - can be both 0 and 1 at once. This phenomenon, coupled with algorithms for quantum computing allows certain problems to be calculated with a much lower level of computational effort.
Communications systems remain secure by making it prohibitively difficult to decrypt the transmitted information without access to the key.
Variants of public key encryption (where everyone can see the public key which is used to encrypt the data, but only the recipient has access to the private key which is needed to decrypt it) rely on it being too difficult to calculate the private key to decrypt data, even when someone has the public key. As the key gets longer, it becomes exponentially more difficult to attack.
Attacking public key encryption involves a lot of computationally-intensive searching and factoring of large numbers. With traditional computers, these functions are very time-consuming, even for modern processors. So the security of public key encryption relies on searching and factoring numbers being very complex. However, algorithms for quantum computing that exploit the superposition property of quantum computers have dramatically changed this.
A quantum computer can attack public key encryption much more effectively, drastically reducing the security of communications systems.
For example Shor’s algorithm can quickly factor numbers, while Grover’s algorithm speeds up searches.
As factoring and searching are exactly the functions which make public key encryption so secure, advances in quantum computation, such as these algorithms, cryptographic problems which were difficult and not solvable in reasonable timeframes using conventional computing, have become fairly trivial problems for a quantum computer. Across the defence industry, it is evident that quantum computing poses a credible threat to some security mechanisms currently in use. In fact, it makes some of our current generation encryption technologies obsolete. In some cases, quantum computing effectively halves the length of the key.
As quantum processing power increases and programming techniques advance, the threat to eavesdrop on traffic, or to decrypt historic data grows significantly as well.
Quantum safe cryptography
Does quantum computing mean all encryption is compromised? Not completely. There are challenges to manufacture quantum processors which are effective against current algorithms. But state-of-the-art technology is advancing rapidly and the true capabilities available in most research labs remains secret (especially in some government research facilities).
To counter the threat posed by quantum computing, the concept of ‘quantum-safe cryptography’ has developed in recent years. This uses encryption algorithms in conjunction with other mathematical functions to encrypt data in ways which are difficult for quantum computing to analyze. Quantum-safe algorithms have been developed, and equipment using these algorithms is beginning to become available commercially.
In 2015, a small company specializing in quantum-safe cryptography participated in the NCI Agency’s cyber security technology incubator, as part of the Agency’s Innovation Programme. PostQuantum Ltd produced a messaging App which protects data with a quantum-safe algorithm and additional security features. PostQuantum Ltd is now delivering quantum safe cryptographic products to commercial telecom operators, IT providers and the finance industry.
While quantum technologies pose a threat to encryption, they offer a solution to another communications challenge – detecting whether your communications have been compromised. Whenever an unknown quantum state is measured, the state changes in some way. This provides a very useful property to identify if communications have been intercepted and it is exploited in Quantum Key Distribution (QKD).
QKD is the first quantum technology to emerge in commercial use. Civilian standards for QKD are already being developed by the European Telecommunications Standards Institute (ETSI) and others, while companies such as IDquantique offer commercial services.
QKD exploits the entanglement property of quantum mechanics to securely distribute keys for conventional communication - the most sensitive element of the communication process. Conventional security mechanisms (often employing quantum-safe cryptography) are then used to protect traffic transmitted conventionally.
The same quantum principles of QKD can be applied to the entire communication network. A 2000km quantum communication link now operates between Beijing and Shanghai demonstrating the concept is viable for long distances. In August 2016, China also launched a satellite purported to be able to generate and distribute quantum encryption keys from space.
Most current technology addresses point-to-point communications, as using this technology for many-to-many network connections is complex. However, there is significant research activity in this area from both the government and commercial sectors, so rapid advances will happen.
And as the use of QKD becomes more widespread, this tool, while useful for national and international defence, could also pose a threat to our societies as it offers our adversaries coding techniques that are guaranteed to be unbreakable.
Quantum technologies in sensing has huge potential, but is likely to have an impact beyond the three to five years window of our Technology Watch series. However quantum radar, and new mechanisms to sense minute changes in gravity, electric field or magnetism have the potential to detect hidden massive objects (machinery and weapons), or movement of people beyond the line of sight, for example in the urban canyons of a modern city environment. Quantum sensing could make our oceans essentially transparent.
Quantum radars exploit entanglement and can significantly enhance target detection capabilities. These systems rely on entangled photons – the elementary particles of the electromagnetic field. As such, quantum radars offer a significant improvement in performance and the possibility of detecting and identifying stealth targets. Also, they are more resilient against the use of jamming countermeasures.
Quantum technology is now firmly into the realm of science fact rather than fiction, as it is providing (or promising) a step-change in the technological capabilities of C4ISR systems – and those of our adversaries.