Quantum Hardware Platforms: Coherence vs. Gate-Error Circuit Budget

Real quantum hardware comes in genuinely different physical flavors, and each one trades speed for staying power in a different way. This simulation puts four real platform families side by side — superconducting transmons, trapped ions, neutral-atom (Rydberg) arrays and photonic chips — and runs the same real T1/T2 exponential-decay decoherence model used elsewhere on this site (coherence(t) = exp(−t/T2), with T2 ≤ 2×T1 enforced) against each one's real characteristic gate time and 2-qubit gate fidelity. The result is a genuine circuit-depth budget: the number of gate operations each platform can actually execute before the circuit's success probability drops below a usable 50%. Set a target circuit depth and watch which real platforms can and can't reach it — and see why, in practice, a slower but more accurate qubit (trapped ions) can out-run a faster but noisier one (superconducting), while a near-infinite-coherence photonic qubit is bottlenecked by probabilistic gates instead of decoherence at all.