# At the racing track of quantum computers

*In a sense, quantum computers are already much more powerful than traditional supercomputers. In the form of the ever-useful car analogy: quantum computers of today are like the fastest racing cars ever built, or even imagined. There is a caveat, however.*

Like racing cars, quantum computers are supremely powerful for special tasks. Where the automotive champions make record-breaking lap times only on well-maintained, purpose-built tracks, quantum computers excel at solving a specific set of problems that fit their unique quantum-derived capabilities. Just as you wouldn’t take a racing car for an off-road adventure into the wilderness, you wouldn’t use a quantum computer to calculate your taxes.

Even with a limited selection of suitable problem types, the speed-up for general computational modelling that quantum computers can provide is revolutionary. Despite their demonstrated speed and the ability to perform calculations much too complex for ordinary computers, quantum computers presently suffer from a major drawback: they quickly run out of steam. The calculations they can perform are thus too short for being useful. The batteries of our superfast futuristic racing car discharge much too quickly; after driving for a metre or two, the car stops and needs to be recharged. This is of course not very useful in a race around a real-world track. In addition, steering and controlling the racing car/quantum computer is tricky. After turning left and right a couple of times, the steering wheel detaches, and the technological marvel crashes.

The suboptimal battery life and steering capacity are, however, only temporary problems that will be overcome with further engineering efforts. The base for a super-fast machine is already in place, now we just need to get past the teething troubles. Next, let’s have a look at a few areas, where quantum computing is making an impact already now.

## Academia and industry

Quantum computing and quantum technologies in general are prime examples of where collaboration and rapport between academia and industry is driving a technology forward at an accelerated pace. Development of quantum computers and quantum computing has a solid base in basic research. The potential of quantum computing is also recognised in industry. Quantum hardware and software companies are flourishing alongside academic actors, all preparing for the upcoming quantum revolution. To take advantage of the increase in computational power throughout society, it is important to also activate the actual end-users of the new technology, those for whom quantum computing is a tool to be used for achieving their specific goals. Formulating problems in a form suitable for the quantum computers of tomorrow takes time. The sooner one starts, the more competitive a head-start one gains.

## Pharmacological research

Oft-cited applications of quantum computing are medical research and drug development. For good reason. One of the areas where quantum computers are expected to excel is in modelling and providing insight into the intricate dance of electrons. This dance, choreographed by the laws of quantum mechanics, provides the glue that binds atoms together, thus forming the molecules and matter around us. The interaction of drug molecules with proteins and enzymes in our bodies is a cornerstone of modern medicine. These same interactions lie at the heart of all other electronic structure problems, ranging from solar cells and new batteries to green chemical catalysis. In fact, the original motivation for constructing quantum computers in the first place was the need to solve quantum mechanical problems more efficiently.

## Digital security

Much of present-day encryption is based on mathematical problems that due to their nature are practically impossible to solve using traditional computers. One such problem is the factoring of large integers into their prime number constituents. Small integers are easy: 15 is a product of 3 and 5. When the number to decompose is hundreds of digits long, even the most powerful supercomputers would need a time exceeding the age of the universe to solve the problem. For quantum computers, this task is easy, as shown by Peter Shor already in 1994. This poses a real danger to digital security. The problem is quite similar to the famous “year 2000” bug. We have known about the threat for a long time. We also know how to fix it. In contrast to the Y2K bug, the quantum threat to encryption is more insidious, however, as a definite dead-line for when the fixes have to be in place is lacking. It thus becomes too easy to push forward the transition to quantum-safe encryption, even if the security of our digital society requires action already now.

## Quantum supercomputers

As quantum computers are not general-purpose calculators, they will not replace supercomputers, but merge with them. Together, the two technologies provide a tremendously powerful tool for science by enabling solutions to computational problems that today are completely impossible to tackle. In fact, the expected leap in computational capacity is so huge, that just imagining what one could do with the quantum-boosted supercomputers is difficult! The first step is to set up a hybrid high-performance computing/quantum computing infrastructure available for end-users in academia and industry. The first connections between supercomputers and quantum computers have recently been demonstrated around the world. Here, a Nordic quantum milestone was reached a couple of weeks ago, when we combined the LUMI supercomputer located in Finland with the Chalmers/Wallenberg Centre for Quantum Technologies QAL 9000 quantum computer in Sweden, and ran the first cross-border quantum algorithm in the Nordics. Next, time to enable new science!

The practice sessions are done. The quantum racing cars are lining up to their first real race. Now is the time to reserve your front row seats!

Published on the World Quantum Day, April 14, 2022

*Author:* **Mikael Johansson**, Quantum Strategist at CSC – IT Center for Science, Finland.