OQFT Depth Crossover, the Optimistic QFT Beats the Textbook Circuit From 68 Qubits On

Fri, 13 Nov 2026 00:00:00 +0000

The optimistic QFT is built for big registers. Everyone working with it knows that. The less obvious question is where “big” starts, because below some size the textbook circuit is simply shallower, and a compiler that swaps in OQFT everywhere would make small circuits worse.

So we ran oqft stats at an error target of 0.01 for every register size from 32 to 80 qubits, plus a few larger ones, and wrote down depth and gate count for both circuits. Depth counts every gate as one layer, with gates on separate qubits sharing a layer.

Circuit Depth on oqft.com

OQFT Depth Crossover, the Optimistic QFT Beats the Textbook Circuit From 68 Qubits On