Quantum Computers – Kissed by Physics

What would take a supercomputer a century – the quantum computer can do in just a few seconds. But the top computers of the future will not only deliver results for previously unsolvable tasks, they will also easily crack our passwords.

With quantum technology, complicated calculations can be solved much faster than with conventional computers. Photo: Fotolia – Weissblick

“A normal computer bit is either 1 or 0, On or Off.” The explanation comes from an unusual source – the charismatic Canadian Prime Minister Justin Trudeau surprised reporters with his expertise when he answered the question about the meaning of quantum computers at a press conference with a definition: “A quantum state is much more complex, however, because it can be wave and particle at the same time”. The scientists present let him get away with the fact that this explanation was not one hundred percent correct – Trudeau had the laughs on his side. And at least he announced on this occasion that his government would invest 50 million Canadian dollars in this technology.

Specialty: Parallel Calculation of Multiple Options

Again, there are very specific reasons for this. Quantum computers promise to solve problems on which conventional supercomputers bite their teeth out in the shortest possible time. Quantum computers play to their strengths when it comes to calculating a very large number of possible results in parallel. A classic example is known to mathematicians as the “Problem of the Travelling Salesman”: For example, a salesman has to visit 15 cities and cover the shortest possible distance. Sounds trivial and should be detachable from any commercial navigation system? Not at all – because there are 43 billion ways to sort the order of the 15 cities. To compare them all, today’s most powerful supercomputers would take almost a century. Curtain up for the quantum computer: It solves the task described in seconds.

The universal Google quantum computer is suitable for many experimental computing operations. Photo: Google, Eric Lukero

Prime Minister Trudeau wanted to explain what this achievement is based on in his statement. Technically speaking, maybe he should have said: Quantum computers are based on so-called qubits. In them, the two states 0 and 1 can overlap, technicians speak of “superposition”. The concept combines quantum physics and computer science – and in quantum physics the conditions are by no means as clear as in IT. Another important effect is the so-called entanglement of qubits: If the state of a “gray value bit” changes, all qubits coupled to it assume the same state immediately. These physical effects allow quantum computers to perform extensive parallel calculations almost simultaneously and thus determine the required solution in no time at all.

The Technical Effort is Enormous

What sounds unusual, but still comprehensible in theory, needs a huge technical effort in practice. What this looks like can be admired in the quantum computer research center of IBM in Zurich. There, the scientists cool atoms down to temperatures near absolute zero and bombard them with laser beams to produce entangled qubits. The IT group has currently implemented a system with 20 qubits. In view of today’s 64-bit processors this does not sound like much – but it is enough to solve the problem described above with 15 waypoints to be sorted. As part of its “Q Experience”, IBM provides this massive computing power for a fee. And IBM scientists are already working on the next generation of quantum computers with 50 qubits.

Versatile Applications

There are many applications for the new technology. Volkswagen, for example, is using them to develop new approaches for controlling traffic flows in major cities. For example, the quantum computer analyzed the movement data of 10,000 taxis in Beijing and optimized their routes. Supply chains in logistics can also be improved in this way. Quantum computers are also used for the simulation of molecules in chemistry or materials research, the calculation of weather models or risk assessments in financial mathematics. According to IBM, artificial intelligence and machine learning could also benefit from quantum computing.

With the help of the quantum computer, VW want to optimize both the situation of individual road users and urban traffic planning. Photo: VW

Headaches for Safety Researchers

However, the new technology also carries risks. It is a particular headache for safety researchers. Current encryption methods that protect the transmission of confidential data or access to WIFI networks, for example, are based on calculations with large prime numbers. The security results from the fact that it would take several hundred years to crack the key with current computers. Quantum computers solve such tasks in seconds. Common encryption methods such as RSA are still considered safe from “quantum attacks” because there are still no quantum computers with the required number of qubits. But that could change within the next ten years. One solution: In the future, quantum computers will also be used to generate the keys of ciphering processes. Security is then based on another property of qubits: If the connection is intercepted, this alone would change the information transmitted. The transmitter and receiver could detect whether a third party has logged on to the connection.

The Best of Two Worlds

Not only Canada, but many countries and research institutions are investing massively in the new technology. One of the latest trends: A group of researchers from Microsoft, Columbia University New York and ETH Zurich are proposing a concept for a hybrid computer. It would combine the classical operating methods of today’s computers with quantum computing. Combining the best of both worlds sounds like a good idea – Prime Minister Trudeau would certainly agree.