IonQ vs D-Wave vs Rigetti, what's actually different between them

[NatureBoy86]

These three names come up constantly in quantum computing news but I don't actually understand what separates them, can someone lay it out?

[VacantTundra]

What kind of quantum computer does each company build?
IonQ uses trapped ion qubits, individual charged atoms held in place with electromagnetic fields. D-Wave focuses mainly on quantum annealing, a more specialized approach built for optimization problems rather than general purpose computing, though it's also expanding into gate model systems. Rigetti builds superconducting qubits, the same general approach used by Google and IBM

Which one is actually further along technically?
There's no single agreed answer, IonQ and Rigetti compete more directly on general purpose gate model quantum computing benchmarks, while D-Wave has the longest commercial track record specifically in optimization applications for things like logistics and scheduling

Are they all publicly traded?
Yes, all three trade on US exchanges, IonQ and Rigetti on the Nasdaq or NYSE depending on recent listing changes, and D-Wave on the NYSE, though D-Wave recently announced a move to Nasdaq as well

Which one should I actually pay attention to if I only follow one?
Depends what you care about, IonQ gets the most mainstream coverage and has the highest valuation, D-Wave has real existing commercial customers today, and Rigetti is the smaller, more speculative bet of the three by most measures

[HiggsField29]

Annealing versus gate model is the distinction that actually matters most here, they're not really solving the same kind of problem even though headlines lump them together as competitors