There are many algorithms for which it has been mathematically proven that a quantum computer can generate results that would take a classical computer an unreasonable amount of time to generate. Unfortunately, today’s quantum computers either can’t run those algorithms or can only run simplified versions that classical computers can also handle. This has left the field facing a challenging question: Can we demonstrate the promise of quantum computers on today’s noisy, limited hardware?

That’s a more difficult question than it may first appear. If you generate a result that’s out of reach of today’s regular computers, it may not be possible to verify that you got the right result. And given that today’s quantum computers are somewhat error-prone, getting the wrong result is a distinct possibility. Further, in the absence of a mathematical proof of the capabilities of quantum hardware, it’s possible that a better classical algorithm could outperform the quantum hardware.

These issues inspired IBM to launch a quantum advantage tracker. On Thursday, the company announced three new entries that it says clearly show a quantum advantage, each using a different approach to overcoming errors and validating quantum results. “Trusted computing when you can do classical simulations is irrelevant,” IBM’s Jay Gambetta told Ars. “Trusted computing when you can’t do classical simulations is a big deal.”

None of the results are immediately useful, but they hint that we might be heading in the right direction.

Trust, but verify

At this point, there have been many claims of quantum advantage, and at least one has the potential to be useful. But in a number of high-profile cases, algorithm developers have developed optimized algorithms that have severely reduced the advantage, bringing classical computers back up to par. Another issue is verification. If your quantum computer is generating a statistical pattern by re-running variations on a single set of operations, a systemic error could potentially bias the output, and you couldn’t use a classical computer to check.