The Other Q-Day

Q-Day is a colloquialism to represent a point in time when quantum computers are capable of cracking encryption. I propose that there’s another kind of Q-Day, the day when quantum computers are capable enough to solve problems for businesses that classical systems cannot do on their own. I will call this Commercial Q-Day.

At a point in time we will learn about a quantum computer playing a key role in solving a business problem. “Key” here means without quantum, classical could not solve it in a reasonable amount of time, cost, or other practicality. This doesn’t mean that quantum solved the problem without any classical compute. For the foreseeable future, most quantum compute work will be hybrid, including CPUs, GPUs, and QPUs.

Now, some folks familiar with this space will point to examples of enterprises using quantum to solve a problem. They will point to this or that press release or paper where there is a claim of quantum advantage, or a demonstration of quantum being applied to a business problem. But, this is not the Commercial Q-Day that I am thinking of. The scope should not be a one off, for that looks like a marketing project done for a marketing team. The problem should be an ongoing problem where quantum is used regularly or frequently.

The key point is that the enterprise uses quantum not just once, but regularly or frequently for this problem. And, the business has moved from being quantum curious to being a paying user that relies on quantum to run their operations.

If we look at the current projection of quantum capabilities in vendor roadmaps we can see that powerful quantum computers arrive in 2028. If you have read any of my other Notes you will know that I see ongoing use of AI by quantum companies (eg error correction) and the force of commercialization causing acceleration in roadmaps. Which is why I believe that Commercial Q-Day will arrive sometime in late 2027. That’s not a day. So, let’s pick a day.

Previously, for Encryption Q-Day, I picked June 10th. A midpoint in the year. But, I think Commercial Q-Day happens closer to 2028 than 2026. Thus, I am identifying December 3, 2027 as Commercial Q-Day.

As of this writing, on June 12, 2026, there are 539 days until Commercial Q-Day.

Note: I am focused on gate-based systems and exclude D-Wave from this analysis, at least until they have a meaningful superconducting product offering.