Gemma Church explains how quantum computers will transform the world of science and engineering - but only if we can reach the million-qubit scale
Quantum computing is moving forward, one qubit at a time. Google’s Sycamore processor has 54 quantum bits (qubits), enough for it to establish ‘quantum supremacy’ back in October 2019.
While a truly remarkable result, the problem they solved was rather academic in nature and of little commercial value. Solving a problem with real world applications using a quantum computer is often referred to as ‘quantum advantage’ and a critical goal for quantum computing.
To get to quantum advantage, we need more high-quality qubits – potentially millions of them. But scaling to anywhere near one million qubits is a highly complex and multi-faceted engineering (and physics) challenge.
From a quantum computing hardware perspective, the main issue is with the qubits themselves. By their very nature, they are error-prone and difficult to control, making quantum computers unstable and highly complex systems. Addressing these errors is key.
Fortunately, something called quantum error correction exists, which is a type of algorithm that corrects the errors. High level, to make error correction work, we need a lot of qubits, and this is where the requirement for millions of qubits comes from.
Building quantum computers that can reach this scale is, therefore, of paramount importance if you are serious about developing useful quantum computers.
There are many ways to build these machines, depending on the type of qubit technology used. Quantum hardware companies are currently trying to scale up their quantum computers and include enough qubits to reach quantum advantage. But, when we get there, how will these computers impact the world of science and engineering?
Well, scientists and engineers can already access the computational power of quantum computers via the cloud. This allows quantum computers to exist in the most suitable locations while end users can access these resources from anywhere, using their own computers. Just as we’ve seen with cloud-accessible supercomputers, the cloud is a viable way for scientists to access quantum machines and conduct cutting-edge research.
As we scale up to millions of qubits, the cloud will remain a viable option for scientists to access quantum resources. QCaaS (Quantum Computing as a Service) models will open the door to anyone who requires access, for example. Other institutions may partner with quantum computing companies to get access to their resources, and we may see on-site installations at some institutions.
Whatever access model one uses, there are many different applications for quantum computing, which scale somewhat with the number of high-quality qubits available.
As we increase the number of high-quality qubits, the first ‘useful’ applications are likely to be realised in chemistry. While there has been much progress in the development of classical algorithms for chemistry, the vast processing power of quantum computers means you will be able to simulate complex chemical compounds.
For large molecules, for example, classical simulation methods have prohibitive run times. Using a quantum computer, scientists can probe molecules that such classical simulations could not feasibly consider – as well as, in some cases, removing the requirement for scientists to go into the lab. This saves time and money, with implications across multiple industries for exponential speed up.
For example, scientists could use a quantum computer to better predict the behaviour of a new drug and its chemical interactions or to screen different battery materials, without using a ‘trial and error’ approach. Quantum computers could also help scientists investigate eco-friendly alternatives to the Haber-Bosch process, which dominates in today’s fertiliser production market. As quantum computing scales, scientists can tackle more complex and larger molecules.
Another area of investigation is to simulate certain physics problems. The Hubbard model, for example, is a popular way to model electrons in an atom - and a quantum computer could provide researchers with a more advanced way to capture atomic behaviour in everything from metallic to insulating materials and for research into areas including magnetism and superconductivity.
CFD (Computational Fluid Dynamics) is another major area of development. The aerospace industry is already investigating the viability of quantum computing to advance engine performance and vehicle designs, for example. Finally, health economics and scheduling are emerging areas, where quantum computers could boost the operating efficiencies of hospitals.
As we continue to scale, additional applications will be unlocked in cybersecurity, financial modelling, logistics optimisation, artificial intelligence and machine learning, and even climate change and weather forecasting.
Getting quantum ready
For scientists and engineers, there are many ways to prepare for the emergence of quantum computing in your discipline. To start, it’s important to understand the current quantum computing timelines and which areas of science and engineering will be impacted first.
There are already a handful of QCaaS options available that allow you to get some experience with qubits and quantum circuits. Most of these rely on the Python programming language and have user-friendly interfaces to help you get started and experimenting within the quantum world.
While such solutions are useful to help you build your knowledge of quantum computing, there is also a rising trend among providers to produce black box functions that tackle real world problems while managing all the quantum parts behind the scenes. Users with little to no quantum background could make use of these functions just in the same way that, today, they may download and utilize an optimisation package without knowing exactly how it works.
For those that want to go further into exploring the quantum realm, it may be necessary to go under the hood and start grappling with some real quantum algorithms.
As we approach (and go beyond) quantum advantage, there will be a demand for mapping classical problems to quantum algorithms. Those individuals that can understand – and work in – this space will be able to collaborate with quantum scientists to find novel solutions to some of the world’s most complex science and engineering challenges.
Ultimately, everyone will differ with how far they want to go with their quantum journey, and that’s OK. Even without any experience, users will one day be able to reap the benefits of quantum computing. Right now, you can get online and start learning by entangling actual qubits via the cloud, and from there the journey never really ends.
As the saying goes, every journey starts with one small (maybe quantum) step and, for scientists and engineers who want to reap the full rewards of quantum computing, the time to act is now. By getting ‘quantum ready’ you can be part of shaping a big part of the future of computing in a way that not only boosts your research - but also helps the world’s scientific communities unlock the full potential of quantum computing.
Gemma Church is the head of comms at Universal Quantum, a UK quantum hardware company that’s building the world’s first million-qubit quantum computer.
