The first quantum-cryptographically secured connection between two federal authorities was presented to the public on Monday. The project is part of a whole series of research initiatives with which the German government wants to secure the “technological sovereignty” of Europe. She identified quantum technology as one of the key technologies.
The fact that quantum physics is considered incomprehensible and puzzling is not only due to the rather abstract mathematics on which the theory is based. What is particularly irritating is the permanent violation of common sense by quantum systems: The mostly microscopic quantum objects move through barriers like ghosts, are apparently in two different places at the same time and can instantly influence each other in a puzzling way, even over great distances. Quantum technology makes targeted use of these phenomena by specifically preparing and manipulating the states of individual quantum systems.
In this way one can – at least theoretically – carry out calculations with quantum computers that cannot be carried out with classical computers. Quantum cryptography makes it possible to encrypt data so that it cannot be cracked, and quantum sensors can be used to measure things that were previously considered impossible to measure. Although it sounds like an empty phrase, the potential of this technology is actually “revolutionary”. However, it is still largely theoretical – much is still at an early stage of research.
This article is from issue 5/2021 of the Technology Review. The magazine will be available from July 8th, 2021 in stores and directly in the heise shop. Highlights from the magazine:
Billions in funding since 2018
For some time now, however, there have been rapid technical advances in the field of quantum technology. Quantum cryptography, for example, the mathematically verifiable unbreakable encryption of data, was still considered an exciting theoretical concept in the 1980s and was first implemented in practice in the early 2000s – albeit only in the laboratory. The same applies to quantum computing: in 1994, the mathematician Peter Shor devised a method to use quantum computers to break down numbers into their prime factors – a core component of classic encryption algorithms. In 2001, IBM ran the algorithm for the first time on a quantum computer, which, however, was very small and could only break down the number 15 into its components 5 and 3.
In many such research projects, European researchers came out on top. However, they have been made technically usable for around 20 years mainly by large US corporations such as Google and IBM, which primarily want to use the potential of quantum computers for themselves. Quantum computers can be used, for example, to simulate the design of new molecules for drugs, predict traffic flows in megacities in real time, or take machine learning to a new level.
The physicist Tommaso Calarco from Forschungszentrum Jülich, together with colleagues, therefore initiated a kind of roadmap, a plan for a Europe-wide, coordinated research program that should make it possible to use the “second quantum revolution” also technically. The “Quantum Manifesto” was signed by over 900 researchers when it was published in 2016. In 2018, the EU decided to actually support the development of quantum technology with one billion euros – albeit over a ten-year period. In addition to the EU package, individual EU states such as Germany decided on further national funding programs. In Germany, the government recently provided almost two billion euros in funding for the development of quantum technology.
Annoying technical restrictions
The funding focuses on three technical areas with very different degrees of technical maturity and application potential: quantum computers, quantum communication and quantum sensors. From a technical point of view, the development is furthest in quantum communication: as early as the early 2000s, the first commercially available systems were available with which tap-proof quantum communication can be implemented. However, these systems could not prevail for three main reasons:
First, they solved a very theoretical problem: strong, well-implemented, classic cryptography is theoretically vulnerable. In practice, however, it requires attackers with considerable resources to break this encryption.
Second, the technology is the only one that is theoretically – mathematically provable – not open to attack. In practical installation, however, there are also gaps in quantum encryption that hackers can exploit. The Russian physicist Vadim Makarov, for example, was able to show in 2008 with its Quantum Hacking Lab how photon detectors can be “blinded” in order to outsmart quantum cryptographic systems.
Thirdly, there are annoying technical restrictions: Until now, quantum cryptographic connections can only be established between two points – further networking is only possible at the expense of security. In addition, the range of such connections is limited to a few hundred kilometers. Researchers in the Netherlands are working on a quantum repeater that allows more than two points to be genuinely networked, but the work is still at a very early stage.
The technology is necessary
For all three points, however, the situation has changed significantly over the past ten years. State or at least state-supported cyber attacks with considerable resources are now the order of the day. In addition, potential attackers – but also competitors – invest considerable resources in the development of quantum computers, with the help of which conventional encryption can easily be cracked. At the same time, China is massively expanding its own quantum cryptographic network and – even if it may be technically imperfect – is gaining valuable practical experience with it. This has led to a re-evaluation of quantum technology.
There is now a great deal of interest, especially on the corporate side, in examining the potential of quantum computing and quantum communication specifically for its suitability for practical use. While computing is primarily about exploring how optimization problems can be practically transferred to quantum computers and what can actually be extracted from the currently still very limited quantum hardware, the focus in quantum communication is on the stability and practicality of the components.
In the area of quantum computers, Europe is also relying on the independent development of its own hardware in order not to fall into a one-sided technical dependency. The Europeans’ chances are not as bad as they look at first glance. Because Google and IBM are currently the most advanced in building quantum computers – both rely on superconducting loops in their quantum processors. In the OpenSuperQ project, European researchers want to catch up within the next five years and build their own superconducting quantum chip with 50 qubits. In any case, the researchers see the main task in developing a functioning error correction for the quantum computer – a problem that all research groups around the world are still working on.
In addition, superconducting chips are not the only hardware to build a quantum computer – and the question of which hardware is best has not yet been decided. In the AQTION project, for example, European researchers are developing a quantum computer based on so-called ion traps. Ions, which are held in place by electrical fields and excited with laser pulses, serve as qubits. Within two years, they were able to accommodate the prototype of such a quantum computer in a server module. In other working groups, scientists are researching spin qubits in silicon or ion traps that are controlled with microwaves.
The entire field of quantum technology is very research-intensive – technically highly specialized developments such as extremely low-noise electronics for controlling the quantum systems are closely interlinked with experimental and theoretical basic research. In order to get ahead at this point, the quantum community has so far relied on strong international cooperation.
In August 2016, for example, a rocket was launched from the Chinese spaceport Jiuquan and carried a communications satellite into near-Earth orbit, from which a quantum connection between two continents was realized for the first time. This experiment was made possible by the collaboration between Jian-Wei Pan, the Chinese University of Science and Technology and the quantum pioneer Anton Zeilinger from Vienna. Pan had written his doctoral thesis at Zeilinger.
Such a carefree cooperation is likely to become more difficult in the future. Not only with researchers in China: The rules for projects in the research framework program Horizon Europe could prove to be groundbreaking. For months, however, the EU Commission and the governments of the member states discussed the participation of researchers from “third countries” in “sensitive research projects”, including in the field of quantum technology. An original draft that would have excluded researchers from Switzerland, Israel or Great Britain from participating in such projects in the future was deleted at the initiative of the German government, among other things. According to the compromise, which the EU Commission still has to agree to, the applicants “only” have to prove credibly that their participation would not harm European interests, security and autonomy.
How to turn it around: International cooperation remains a sticking point in the development of quantum technology. So whether a purely European quantum technology can ever be realized can at least be viewed as very unlikely. But that is commonplace for quantum researchers.