Sooner than expected? Useful quantum error correction promised for 2028. - Ars Technica

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Quantum computing news usually picks up near the end of the year, as companies try to provide evidence that they are hitting benchmarks on time. However, there have been interesting announcements as the summer starts this year, from incremental progress to attention-grabbing promises. As we did earlier this month, Ars has a rundown of some of the most significant announcements.

These include a promise of useful, error-corrected quantum computing as soon as 2028, details on an updated trapped ion processor, and a case in which claims of quantum supremacy have been cut back a bit thanks to advances in more traditional algorithms.

2028 is remarkably soon

Many people in the field expect that useful quantum computers are still about five to 10 years away. While there may be a few useful algorithms that can be run on existing error-prone hardware, almost all of the interesting problems that quantum computing can be applied to will require some form of error correction enabled by linking a small collection of hardware qubits together into what’s called a logical qubit. Logical qubits include the redundant storage of information along with neighboring qubits that can be measured to determine when errors occur and how to fix them.

To do useful computations, you need a healthy number of logical qubits—roughly 100 to provide a complete model of the behavior of some simple chemicals, to tens of thousands to perform complicated algorithms like the one that can break encryption. (So, any definition of “useful” comes with the important caveat “for whom?”) That means, at a minimum, we’re going to need thousands of high-quality hardware qubits to build a useful error-corrected machine.

At the moment, existing qubit technologies offer either high quality or lots of qubits. There are roadmaps from here to where we want to be, but they require a few years of incremental progress. Hence, the five- to 10-year estimates.

On Monday, Amazon and QuEra claimed they will get there in two years. “By 2028, we will bring Libra, a Megaquop-scale device, capable of executing one million quantum operations over hundreds of logical qubits, to our customers, enabling first scientific applications in quantum chemistry, high-energy physics, and materials simulation that are beyond the reach of classical and Noisy Intermediate-Scale Quantum (NISQ) computers today,” Amazon’s statement said.

Those customers currently have access to a number of different quantum computing technologies via its Braket cloud service. Libra is hardware that will be provided by QuEra, a startup based in the Boston area that is pursuing neutral atom quantum computing by sharing staff and a long-term intellectual property agreement with research groups at Harvard University and the Massachusetts Institute of Technology.

Neutral atom quantum computing is based on our ability to use lasers to cool individual atoms and trap them in a grid of overlapping light beams, with the qubit being stored in the spin of the nucleus. Separate laser systems can also move atoms around, providing any-to-any connectivity, which enables considerable flexibility for algorithmic and error-correction purposes. The technology currently falls into the “easy to make lots of them” category of hardware qubits—QuEra’s academic partners have demonstrated a 3,000 qubit grid.

However, the operation of these systems tends to heat the atoms, and moving them around is slow, so they get lost at a problematic frequency. While the people behind QuEra have demonstrated some impressive error correction, there was still considerable work to do. Understanding how the company plans to get from its current demonstrations to a high-quality system will be essential for evaluating how likely we are to start seeing error-corrected computation before the decade wraps up.

This makes the timing of Amazon’s announcement very frustrating, because QuEra intends to lay out a detailed roadmap to its Libra system next week. We’ve been promised a full briefing ahead of that, but for now, all we can say is that the two companies involved aren’t prone to hype, and probably wouldn’t be announcing this if they didn’t have very good reasons to expect things to work out.

A formal description of Helios

In November, Quantinuum announced its next quantum computing hardware, named Helios, based on trapped ion technology. Trapped ions have some things in common with neutral atoms, but instead of a laser...