Well, quantum computers have been extraordinarily difficult and costly things to lash together, but they are being assembled now by US gummit researchers. They are fantastic at searching enormous search spaces because they can represent 2 raised to the number of bits in the CPU possibilities simultaneously. It’s like being able to get an excursion into that many alternative universes. The thermodynamics of your old fashioned von Neumann computations do not apply here.
Yes, they are up to about four bits, I follow some of the papers. I think we have a decade or two before we need to worry. Then I’ll switch to random detanglement encryption with noncoherent spin state, because by then our computers will also use QC at the core.