From Extreme Tech
|Google Announces ‘Bristlecone’ Quantum Computing Chip|
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.