Until recently, it seemed like Google was leading the pack when it came to creating a quantum computer that could surpass the abilities of conventional computers. In a Nature article published in March 2017, the search giant set out ambitious plans to commercialise quantum technology in the next five years. Shortly after that, Google said it intended to achieve something it’s calling ‘quantum supremacy’ with a 49-qubit computer by the end of 2017.

Now, quantum supremacy, which roughly refers to the point where a quantum computer can crunch sums that a conventional computer couldn’t hope to simulate, isn’t exactly a widely accepted term within the quantum community. Those sceptical of Google’s quantum project – or at least the way it talks about quantum computing – argue that supremacy is essentially an arbitrary goal set by Google to make it look like it’s making strides in quantum when really it’s just meeting self-imposed targets.

Whether it’s an arbitrary goal or not, Google was pipped to the supremacy post by IBM in November 2017, when the company announced it had built a 50-qubit quantum computer. Even that, however, was far from stable, as the system could only hold its quantum microstate for 90 microseconds, a record, but far from the times needed to make quantum computing practically viable. Just because IBM has built a 50-qubit system, however, doesn’t necessarily mean they’ve cracked supremacy and definitely doesn’t mean that they’ve created a quantum computer that is anywhere near ready for practical use.

Where IBM has gone further than Google, however, is making quantum computers commercially available. Since 2016, it has offered researchers the chance to run experiments on a five-qubit quantum computer via the cloud and at the end of 2017 started making its 20-qubit system available online too.

But quantum computing is by no means a two-horse race. Californian startup Rigetti is focusing on the stability of its own systems rather than just the number of qubits and it could be the first to build a quantum computer that people can actually use. D-Wave, a company based in Vancouver, Canada, has already created what it is calling a 2,000-qubit system although many researchers don’t consider the D-wave systems to be true quantum computers. Intel, too, has skin in the game. In February 2018 the company announced that it had found a way of fabricating quantum chips from silicon, which would make it much easier to produce chips using existing manufacturing methods.