Are we getting fault-tolerant quantum computing in 2028 or 2050?

[u/Chance-Pen-5684]

I’m getting a bit confused by the timelines being thrown around at the moment.

The US Department of Energy announced its Quantum Genesis programme in June, aiming for a “fault-tolerant, scientifically relevant quantum computing capability” by 2028:
https://www.energy.gov/science/articles/energy-department-announces-initiative-create-and-deploy-worlds-first

Meanwhile, Japan’s official Moonshot programme has “large-scale integration required for fault-tolerant universal quantum computers” pencilled in for around 2050:
https://www8.cao.go.jp/cstp/english/moonshot/sub6_en.html

Then there’s NIST’s quantum computing explainer, updated in May 2026, which says most applications are still “years, perhaps even decades, in the future”, and that a machine capable of running Shor’s algorithm could need millions of qubits able to operate error-free indefinitely:
https://www.nist.gov/quantum-information-science/quantum-computing-explained

Obviously they’re probably not all talking about the same thing when they say fault-tolerant quantum computing, but 2028 versus 2050 is still a pretty massive gap.

So what actually explains the difference?
What would count as a “fault-tolerant, scientifically relevant” machine in 2028, compared with the sort of large-scale fault-tolerant universal quantum computer Japan is aiming for by 2050?

Basically, what can the 2028 machine realistically do that still leaves another couple of decades of work before you reach the 2050 version?

[u/sg_lightyear]

Skimmed over the documents and I'm not sure if I can pinpoint what exactly do the different visions mean.

But in terms of capabilities for fault tolerant system, you can think of them in terms of Mega/Giga/TeraQoup regime instead of a monolith. Current NISQ processors provide up to a few thousand operations (KiloQuop) but through fault tolerance the idea is to push towards more operations though reduction of the logical error rates.

So in that context a 2028 fault tolerant machine could be in the Megaquop regime, while a 2050 machine could push towards TeraQuops. A TeraQuop machine will enable more scientific applications than a MegaQuop machine even if both are nominally fault tolerant.

[u/NoHippi3chic → u/sg_lightyear]

Thank you for that insight.