IBM Quantum Cockatoo

Raveh Neeman

doi:10.5281/zenodo.22674814

IBM

IBM Quantum Cockatoo

IBM · superconducting circuits · PLANNED (2027) · qubits not published · access: n/a

architecture: Transmon lattice with tunable couplers · Open on the map

Register profile — the machine's variant of its architecture

qubit type: fixed-frequency transmon

gate mechanism: tunable coupler

connectivity: l-coupler ("universal adapter"), ~1 m in-fridge cable

control: room-temperature RF

control placement: room-temp

readout: dispersive

gate evidence: no published figure

decoder mode: planned — named in a roadmap only

codes: gross

flags: schedule risk

Technologies by layer — the machine's cell per layer

1 Qubit carrier	Transmon · primary ▥ 🔎 fixed-frequency transmon; Kookaburra-class modules (PLANNED 2027)
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 (technologies as Kookaburra)
4 Connectivity / transport	Long-range on-chip couplers (c-couplers, mm-scale) · primary ▣ Fig. 1a (long-range-connected modular hardware) ✅ l-coupler ("universal adapter") on ~1 m in-fridge link; 2Q 99.3% measured Aug 2026 vs 99.9% required
5 Control	Room-temperature electronics + per-qubit coax/flex · primary ▥ 🔎 room-temperature RF control
6 Readout	Dispersive microwave readout (+TWPA, Purcell) · primary ◌ 🔎 dispersive readout
7 Code	Non-local qLDPC codes (bivariate bicycle, 'gross') · primary ▣ Fig. 1a (qLDPC bicycle architecture); §2.1 Review of bivariate bicycle codes ✅ gross code (bivariate-bicycle qLDPC, [[144,12,12]]), intended; bicycle architecture
8 Decoder	Relay-BP for qLDPC (FPGA) · primary ▣ Fig. 5 (12-cycle gross-code decoder floorplan on AMD XCVU19P); §4 ✅ Relay-BP, intended in-loop; FPGA (AMD VU19P) demo 24 ns/BP iteration, <1 µs avg per cycle on stored [[144,12,12]] syndromes
9 Interconnect	Multi-chip modules / l-couplers (same cryostat) · primary ▣ Fig. 2 (module connectivity; code-code adapter between modules) ✅ two Kookaburra-class modules entangled via l-coupler / "universal adapter" (PLANNED 2027); ~1 m in-fridge link, 99.3% 2Q (Aug 2026)
10 Manufacturing	Superconducting-qubit lithography (Al/AlOx/Al junctions, Nb wiring, 300 mm) · primary ◌ 🔎 Superconducting-qubit lithography (Nb/Al JJ, 300 mm) — IBM Albany 300 mm / Anderon foundry; Google Santa Barbara; Rigetti ABAA trimming (97.4% frequency-targeting success); OQC 500-qubit wafer-scale…

Standard records

2Q error under full-width parallel operation → 0.035 · best benchmarked l-coupler error per gate, 235 ns

the 99.3% Aug-2026 l-coupler figure is not in the cited release · Nov 2024 · source

evidence: ✅ 4 / 10