OQFT Cuts QFT Depth From 4096 to 198 on a 2048-Qubit Register

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

The quantum Fourier transform sits in the middle of Shor’s algorithm. Build it the textbook way on 2,048 qubits, the size you’d need for a 2048-bit RSA key, and you get about 2.1 million gates stacked 4,096 layers deep. Most of those gates are tiny rotations that barely change anything. The rest still have to wait their turn.

OQFT 0.3 builds the other version. The optimistic QFT on the same 2,048 qubits takes 198 layers and about 104,000 gates, and it needs no qubits beyond the register itself. It’s right on almost every input. On a small, known slice of inputs it’s badly wrong, and that’s the deal.

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OQFT Cuts QFT Depth From 4096 to 198 on a 2048-Qubit Register