On 13 July 1984, David Deutsch, scientist and leading authority in the field of quantum computing, published Quantum Theory. In this essay, Deutsch demonstrated that physicist Richard Feynman’s theories were correct… Two years before, Feynman had been the first to consider the possibility of using the principles of quantum mechanics to design supercomputers. Almost 25 years have passed since that day. Now, after countless announcements, promises and prototypes, for the most part successful, the first genuine quantum computer is finally about to become a reality. It was presented by IBM last January at CES in Las Vegas, the most important technology fair in the world, when the company finally unveiled its Q System One. The first quantum computer for commercial and scientific use is 2.8 metres tall and protected by a hermetically sealed glass case at the data centre in Poughkeepsie, New York.

But why is this digital innovation so important? Two words: calculation speed. After years of incredibly rapid growth, in keeping with Moore’s law (according to which the speed of processors doubles every 18 to 24 months), the number of transistors that can be inserted in a chip is about to reach its limit. It’s about to come up against an obstacle that’s not easy to get over: the laws of physics.

“Top-of-the-line microprocessors currently have circuit features that are around 14 nanometres across, smaller than most viruses” according to a paper published in Nature. But by the early 2020s, we’ll get to the 2–3-nanometre limit, where features are just 10 atoms across. By that point, it will be almost impossible to control their behaviour”.Transistor dimensions can therefore only be reduced up to a certain point, after which the process must come to an end. For information technology to continue to evolve, it must take a new path. Binary code, the paradigm all computer design has always rested on, must be revolutionised. In classic binary, every bit can appear as either of the two values 0 and 1. Quantum computers work on the principle of superposition, according to which subatomic particles can assume two or more states simultaneously. Therefore, every quantum bit (known as a qubit) can appear not only as 0 or 1 but also both at the same time, as well as all intermediate values, again simultaneously. This means that a quantum computer’s calculation speed can exceed even that of supercomputers (which can perform 120 million billion operations a second).

For the moment, however, the Q System One presented by IBM is still not capable of beating the world’s most powerful supercomputers. It relies on a processor with only 20 qubits. In a few years though, when the processor is predicted to reach 50 qubits, things will change drastically. A raft of new possibilities will open up in the world of information technology. Fair enough, but what kind of possibilities? One example, provided in 2014 by one of the developers of D-Wave (one of the first quantum prototypes), might make things clearer. “Imagine you’ve only got five minutes to find a specific paragraph in a book that’s in a bookshop with 50 million other texts (all digitized, of course). With a normal computer, it would be an impossible task because you’d have to analyse just one book at a time. But quantum computers can search 50 million texts at the same time and find the paragraph very quickly”.

 Just as 50 million books contain countless words, when you develop a drug, you have to analyse an almost immeasurable number of interactions between molecules, proteins and other components. This is in order to find out if the medicine being developed can cure an illness or improve a physical condition. The amount of combinations that have to be analysed is so high that it currently requires a huge amount of work and time. Quantum computers, however, will be able to analyse the behaviour of multiple molecules and proteins at the same time and obtain results much faster. Besides medicine, the science of meteorology will also be transformed by the impact of quantum computers. The mathematical models needed to predict the weather are incredibly complex. This is why, despite great progress in the last few years, placing total trust in forecasts can play tricks. For quantum computers, quickly analysing all the data needed to create new meteorological models will be much simpler. It will allow us not only to make far more accurate and constantly updated weather forecasts but also to study climate change in depth and better understand what’s influencing it.

Machine learning (the algorithm for machine learning based on artificial intelligence) needs to analyse hundreds of thousands of bits of data and be trained, sometimes for weeks, to learn, for example, how to recognise a face. In this respect, quantum computers will not only make the training phase much faster, but also improve the precision of estimates and push artificial intelligence on to the next evolutionary leap. According to developer Tim Lynch, AI’s ability to translate from one language to another and hold a normal conversation with human beings (two tasks with which machine learning algorithms are still struggling to cope) will progress enormously thanks to quantum technology. The same is true of AI’s ability to generalise and understand abstract concepts, which currently only humans can do. It’s thanks to these technological innovations that we’re getting closer to the big and disquieting goal of human-level artificial intelligence.

In the cybersecurity sector, quantum computers offer just as much potential as they pose a threat. The reason is simple. All current encryption systems will become obsolete. Most online security systems are based on the fact that computers have to waste a considerable amount of energy and a lot of time to decrypt codes. This won’t be the case, however, for quantum computers, which will be able to crack any protection quickly. But there’s an upside. Those same quantum computers will allow us to develop new forms of encryption and protection for sensitive data. The battle between computer pirates and cybersecurity experts is still bound to last a long time.