Google makes the world’s top search engine, mobile OS, and plenty of other consumer products. However, it also makes big bets on emerging technology like machine learning. That technology is beginning to make an impact on Google’s products, but its work on quantum computing is more theoretical. Maybe not for long, though. Google has just announced a new “Bristlecone” custom quantum computing chip that could lead to a major breakthrough known as “quantum supremacy.”
A quantum computer can take various forms — they could even run on a liquid or gas medium rather than a computer chip. What really sets a quantum computer apart from a regular digital computer is the fundamental nature of how data is encoded via quantum properties like superposition or entanglement. A digital bit is either 0 or 1, but a quantum bit (or qubit) can be 0, 1 or a superposition of both states. Google’s new Bristlecone chip has a whopping 72 qubits compared with just nine qubits in the last one.
One of the greatest challenges in making a quantum computer viable is countering so-called quantum decoherence. Interference from the environment causes incorrect calculations and a higher error rate than any standard digital computer. You can compensate for errors by shielding your computer from interference, for example by cooling it to extremely low temperatures. You can also correct for some error in a quantum system. Google’s previous 9-qubit linear quantum computer managed impressively low error rates of between 0.1 and 1 percent.
Google intends to continue focusing on keeping the error rate down with first and second order error-correction with a technique called surface code. Researchers believe this will allow for the development of quantum algorithms on actual hardware like the Bristlecone chip. Google says that the Bristlecone chip could maintain sufficiently low error rates to reach a significant threshold known as quantum supremacy. That’s the point at which a quantum computer can perform a well-defined calculation faster than a digital supercomputer. Past estimates have suggested you’d need at least 50 qubits at low decoherence to accomplish that feat, so Google could well be within striking distance.
The new chips are being operated in Google’s Quantum AI lab right now. Google researchers have also developed new benchmarking tools specifically for measuring the performance of Bristlecone. It’s possible Google will announce significant breakthroughs in the coming years thanks to this new quantum hardware. However, it might take quite a bit longer before quantum computing affects your life.