IBM Quantum Heron r2
IBM Quantum Heron r2
Register profile — the machine's variant of its architecture
qubit type: fixed-frequency transmon + flux-tunable coupler
gate mechanism: native CZ
connectivity: heavy-hex, mean degree 2.3
control: room-temperature RF; cryo-CMOS flux control demonstrated Mar 2026 (16 flux channels per ASIC)
control placement: room-temp + cryo-CMOS (demo)
readout: multiplexed dispersive; dynamic circuits in production
gate evidence: the vendor's datasheet or dashboard
codes: heavy_hex, quantum_repetition, rotated_surface, spacetime_circuit, steane
Technologies by layer — the machine's cell per layer
| 1 Qubit carrier | |
| 2 Encoding | Bare physical qubit (no encoding) · primary ◌ 🔎 Bare two-level subspace — Computational subspace of an anharmonic oscillator; leakage to |2⟩ is the price. |
| 3 Gate mechanism | Tunable-coupler CZ / iSWAP · primary ▣ Fig. 5 (ibm_fez CZ edges, 2Q error map); Methods: IBM hardware ✅ native CZ via flux-tunable coupler, ZZ-free idling; median CZ error 2.03×10⁻³ (2nd source ≈3×10⁻³) (r2, 2024) |
| 4 Connectivity / transport | Static nearest-neighbour lattice · primary ▣ Fig. 1b (heavy-hexagon embedding); Fig. 5 (ibm_fez connectivity) ✅ heavy-hex, degree ≤3, mean 2.3; 156 q, 176 couplers |
| 5 Control | Room-temperature electronics + per-qubit coax/flex · primary ▦ ✅ room-temperature RF with high-density flex cabling; RT RF kept in hybrid with cryo-CMOS flux ASICs in the Mar 2026 demo Cryo-CMOS controller (4 K / mK) · alternate ▦ ✅ cryo-CMOS flux control demonstrated on r2: 16 programmable flux channels per ASIC, multiple ASICs, hybrid with RT RF (APS, 16 Mar 2026) |
| 6 Readout | Dispersive microwave readout (+TWPA, Purcell) · primary ▣ Fig. 5 (readout error map); Methods: IBM hardware ✅ multiplexed dispersive; median readout error 1.67×10⁻² (r2); mid-circuit measurement + feed-forward in production (dynamic circuits) |
| 7 Code | Rotated surface code (+ yoked variants) · primary ▤ abstract; memory results ✅ rotated surface d=3 and (3,5)/(5,3) memory up to 10 QEC cycles on ibm_aachen, ibm_marrakesh, ibm_fez (sweep 7 Oct 2026, source read) Error-detection codes ([[4,2,2]], d=2 surface, iceberg, spacetime) · alternate ▣ Fig. 3a,b (injection layout, post-selection circuit) ✅ rotated_surface magic-state injection with post-selection only; no below-threshold memory, no Λ, no closed-loop correction Magic-state factory (cultivation / distillation / code switching) · alternate ▣ Fig. 3 (magic-state injection); Fig. 4 (|H_L>, |T_L> density matrices) ✅ magic-state injection on ibm_fez (rotated surface): |H_L⟩ 0.8806(2), |T_L⟩ 0.8665(3) at 36.28% acceptance (2026) |
| 8 Decoder | — none — nothing in this layer ▣ Fig. 3b (post-selection); Methods: Implementation of the experiment ✅ no decoder in loop; no closed-loop correction (post-selection / replay only) |
| 9 Interconnect | — none — nothing in this layer ◌ 🔎 monolithic single 156-q die; no interconnect in production (m-coupler prototyped on Crossbill, l-coupler on Flamingo) |
| 10 Manufacturing | Superconducting-qubit lithography (Al/AlOx/Al junctions, Nb wiring, 300 mm) · primary ◌ 🔎 IBM 300 mm Albany superconducting-qubit lithography; flip-chip + TSV + multi-level wiring 300 mm CMOS foundry (spins, cryo-CMOS, superconducting wiring) · alternate ▦ 🔎 CMOS-fabricated cryo-CMOS flux-control ASICs (16 channels per ASIC, Mar 2026 demo) |
Standard records
acceptance fraction → 0.363 · best (magic-state injection)
2026 · source
connectivity degree → 2.3 neighbours · typical (heavy-hex mean, max 3)
2024 · source
evidence: ✅ 9 / 14
Pictures
Every picture carries the story of what it shows and its credit line.
