WHAT IS QUANTUM COMPUTING?
The next generation of computing is on the horizon, with an exponential leap in processing power.
Quantum computers, and adjacent technologies such as quantum networks, could change the way we process data, ripping through existing cryptography and enabling world-changing modelling. But first we’ll have to build them – and figure out how to use them.
At a basic level, traditional computers use binary – every bit is either off or on. That we manage so much with so little is frankly amazing. But quantum takes this further with quantum bits, which have been rather cutely dubbed “qubits”. Thanks to quirky quantum physics, rather than just two positions, qubits can be off or on or both or neither, an idea called superposition. Add to that entanglement
– the idea that qubits can interact – and that gives quantum computers exponential processing power over our existing computers, including supercomputers.
WHY DON’T WE HAVE THEM YET?
Harnessing quantum physics is no easy task. Beyond figuring out how to build one, and sourcing materials and components, quantum computing is full of errors – and they need correcting. Because of the huge amounts of error correction required, we’ll need computers with an excess of qubits in order to fix their own mistakes. And, to be clear, quantum computers already exist.
Who’s making them? IBM’s quantum computer is currently deemed the largest, with 127 qubits. The Eagle, as it’s dubbed, is what’s known as a superconducting quantum computer, which means it’s built using electronic circuits. Google and Chinese university USTC are using similar models, as are Intel and Rigetti.
Canadian startup Xanadu is building a photonics-based machine that uses light as a conductor, while D-Wave is using a technique called quantum annealing. There are different types, and they’re all bewilderingly confusing: trapped ion, quantum dot, molecular magnet and many more.
Some of this hardware is already available to access via the cloud, letting researchers and businesses access early iterations of machines to start to understand them and develop applications. This is likely one way quantum computers will be accessed when they do truly, fully arrive, as such intricate and expensive hardware will be well beyond the means of all but the best funded labs.
WHAT IS QUANTUM SUPREMACY?
Quantum computers are still just computers running equations, and there’s in theory nothing that a quantum model could do that a traditional binary design also couldn’t manage, given all the time in the world. Time is the key difference: quantum computers can manage tasks that would take existing computers far too long – there’s not much point in asking a supercomputer a question and spitting out the answer for your grandchildren to collect, after all. Quantum supremacy is the point where the qubits outpace the bits, when a quantum computer can solve an equation that no classical computer could do in a reasonable amount of time. Depending on who you ask, that nut has already been cracked, by Google’s Sycamore in 2019. IBM disagrees, saying the equation done by Sycamore could be managed by a supercomputer it built called Summit. Since then, Chinese researchers also claim to have managed the milestone.
Given we’re in such early days of quantum development, that suggests supremacy isn’t a very useful milestone.