News about quantum computing usually breaks near the end of the year, as companies try to prove that they hit the benchmarks in time. However, as summer begins this year, there are exciting announcements ranging from incremental progress to eye-catching promises. as we do earlier this monthArs provides a summary of some of the most significant announcements.
These included a promise of useful, error-corrected quantum computing by 2028, details of an updated ion processor, and an event in which claims of quantum supremacy were somewhat toned down thanks to advances in more traditional algorithms.
2028 is very close
Many people in the field expect that useful quantum computers are still about 5-10 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 to which quantum computing can be applied will require some error correction enabled by connecting a small set of hardware qubits called logical qubits. Logical qubits include redundant storage of information alongside neighboring qubits that can be measured to determine when errors occur and how to correct them.
To do useful calculations, you need a healthy number of logical qubits—up to about 100 to provide a complete model of the behavior of some simple chemicals, to tens of thousands to perform complex algorithms that can break encryption. (Thus, any definition of “useful” comes with the important caveat “for whom?”.) This means that, at the very least, we’d need thousands of high-quality hardware qubits to build a useful error-corrected machine.
Current qubit technologies offer either high quality or many qubits. There are road maps from here to where we want to be, but they require several years of growth. So 5-10 year estimates.
