Fujitsu >10,000 physical / ~250 logical (STAR)
Fujitsu >10,000 physical / ~250 logical (STAR)
Register profile — the machine's variant of its architecture
qubit type: transmon
gate mechanism: tunable coupler (assumed)
connectivity: surface-code lattice
control: not published; 'high-density packaging and low-cost control' named as one of four development workstreams
control placement: room-temp
readout: dispersive
gate evidence: a published figure (source class not yet tagged)
codes: rotated_surface
flags: estimate only, no published error rates
Technologies by layer — the machine's cell per layer
| 1 Qubit carrier | |
| 2 Encoding | Bare physical qubit (no encoding) · primary ◌ 🔎 bare transmon two-level subspace; no encoding beyond the physical qubit |
| 3 Gate mechanism | Tunable-coupler CZ / iSWAP · primary ▨ 🔎 tunable coupler (assumed); no error rates published for existing Fujitsu devices |
| 4 Connectivity / transport | Static nearest-neighbour lattice · primary ▣ Fig. 2 (rotated planar surface code, d=5); §III.A ✅ rotated surface-code lattice (degree 4); Cliffords by lattice surgery in STAR |
| 5 Control | — undisclosed — exists, nothing published ▨ §four technology workstreams ✅ 'High-density packaging and low-cost control' and 'chip-to-chip interconnects' named as development workstreams; no wiring scheme published |
| 6 Readout | |
| 7 Code | Magic-state factory (cultivation / distillation / code switching) · alternate ▨ ✅ STAR Ver. 3 (25 Mar 2026) adds logical T gates to analog rotations; required physical error relaxed 1e-4 → 1e-3 Rotated surface code (+ yoked variants) · alternate ▣ Fig. 2 (rotated surface code); Fig. 4–6 (lattice surgery); §III ✅ rotated_surface code; Cliffords fully error-corrected by lattice surgery (STAR, simulation estimates) — (Atlas gap: ∅G-analogrot) · primary ▣ Fig. 7–8 (analog rotation circuits); Fig. 9–12 (injection); §IV; §VI.C ✅ STAR: arbitrary-angle rotations by direct state injection, no distillation; 10⁴ q at p=1e-4 → 64 logical, ≈1.72e7 Cliffords, ≈3.75e4 rotations |
| 8 Decoder | MWPM / Sparse Blossom (+ correlated matching) · primary ▤ §VI.A (logical error of surface-code patch) ✅ PyMatching v2 (MWPM) assumed in STAR resource estimates; not built |
| 9 Interconnect | Multi-chip modules / l-couplers (same cryostat) · primary ▨ 🔎 chip-to-chip interconnect and wiring named as one of four workstreams (plan, FY2030) |
| 10 Manufacturing | Superconducting-qubit lithography (Al/AlOx/Al junctions, Nb wiring, 300 mm) · primary ▨ 🔎 high-precision Josephson-junction fabrication named as one of four workstreams |
evidence: ✅ 6 / 12