Quantum computing news typically comes near the end of the year, as companies try to provide evidence that they are achieving benchmarks on time. However, this year there have been interesting announcements as summer begins, ranging from incremental progress to attention-grabbing promises. As we did earlier this month, Ars has a list of some of the most important announcements.
These include the promise of useful, error-corrected quantum computing by 2028, details on an updated trapped ion processor, and a case in which claims of quantum supremacy have been toned down slightly due to advances in more traditional algorithms.
2028 has come too soon
Many in the field expect useful quantum computers to still be about five to 10 years away. Although there may be some useful algorithms that can be run on existing error-prone hardware, almost all interesting problems to which quantum computing can be applied will require some form of error correction enabled by linking together a small collection of hardware qubits into logical qubits. Logical qubits involve redundant storage of information with neighboring qubits that can be measured to determine when errors occur and how to correct them.
To perform useful calculations, you need a healthy number of logical qubits – around 100 to provide a complete model of the behavior of some simple chemicals, to thousands to execute complex algorithms like those that break encryption. (So, any definition of “useful” comes with the important caveat “for what?”) This means, at a minimum, we would need thousands of high-quality hardware qubits to build a useful error-correcting machine.
At the moment, existing qubit technologies provide either high quality or lots of qubits. We have roadmaps to get to where we want to be, but they require a few years of gradual progress. So, a five to 10 year estimate.
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