Tour de gross: A modular quantum computer based on bivariate bicycle codes
summary
Bicycle architecture uses bivariate bicycle codes — the gross (distance 12, 12 logicals in 288 physical qubits) and two‑gross (distance 18, 12 logicals in 576 physical qubits) — and claims roughly an order‑of‑magnitude more logical qubits per physical budget than comparable surface‑code layouts. Explicit fault‑tolerant instructions (in‑module, intermodule joint measurements, automorphisms, magic‑state injection) are compiled with a Pauli‑based scheme that currently adds ~20× time to measure arbitrary Paulis. Hardware demos show degree‑6, biplanar layouts and meter‑long L‑coupler links achieving ~96.5% entangling fidelity; a 600‑iteration Relay‑BP decoder gives ~10× lower logical error than prior BP variants and enables the presented resource estimates.
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chapters (9)
- 0:00IBM's quantum vision
- 1:48Bivariate bicycle vs surface codes
- 3:18Hardware challenges and progress
- 8:51Modular architecture with L-couplers
- 21:25Logical units and bridge systems
- 32:00Real-time Relay-BP decoder
- 40:13Compiling circuits for bicycle
- 57:47Conclusion and scalability
- 1:03:16Q&A
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