QuantWare Contralto-A17

Raveh Neeman

doi:10.5281/zenodo.22674814

QuantWare · superconducting circuits · DEPLOYED (sold as a QPU; 'Shipping now' on QuantWare's A-line page, Sep 2026; early access since Feb 2025) (2026 (GA; early access Feb 2025)) · 17 physical qubits · access: sold as components

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

Register profile — the machine's variant of its architecture

qubit type: tunable transmon

gate mechanism: flux-tunable couplers and individual Purcell filters (A-line)

connectivity: planar square lattice, d=3 surface patch

control: room-temperature RF

control placement: room-temp

readout: dispersive

gate evidence: no published figure

codes: surface-17

flags: no published error rates, source not confirmed

Technologies by layer — the machine's cell per layer

1 Qubit carrier	Transmon · primary ▦ §Introducing Contralto-A (up to 17 flux-tunable transmon qubits); chip photo ✅ tunable transmon, 17 qubits (9 data + 8 ancilla); early access, general access H1 2026 unconfirmed; no fidelity metrics published
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 ▦ §Introducing Contralto-A (tunable couplers and Purcell filters) ✅ flux-tunable couplers with individual Purcell filters (A-line; D-line uses fixed couplers); no gate fidelities published
4 Connectivity / transport	Static nearest-neighbour lattice · primary ▦ §Introducing Contralto-A (allows distance-3 surface code implementations) 🔎 planar square lattice laid out as a d=3 rotated-surface patch (17 = 9 data + 8 ancilla)
5 Control	Room-temperature electronics + per-qubit coax/flex · primary ◌ §Introducing Contralto-A 🔎 no control scheme published for Contralto-A; the page calls it 'a cost-efficient upgrade path to QuantWare's VIO-powered QPUs', i.e. not a VIO device; customer room-temperature RF (register)
6 Readout	Dispersive microwave readout (+TWPA, Purcell) · primary ▦ §Introducing Contralto-A (Purcell filters) 🔎 dispersive readout with individual Purcell filters (A-line)
7 Code	Rotated surface code (+ yoked variants) · alternate ▦ §Introducing Contralto-A (optimised for running up to a distance-3 surface code) ✅ targeted: d=3 rotated_surface patch (9 data + 8 ancilla); not demonstrated by the vendor — none — nothing in this layer ▨ 🔎 no code run by QuantWare (L0, customers run codes); Contralto-A positioned as d=3 rotated_surface building block
8 Decoder	— none — nothing in this layer ▨ 🔎 no decoder; sold as a component (register decoder=none)
9 Interconnect	— none — nothing in this layer ▨ 🔎 monolithic single 17-q chip; VIO chiplet tiling (no published chip-to-chip fidelity) is the 2028 VIO-40K target
10 Manufacturing	Superconducting-qubit lithography (Al/AlOx/Al junctions, Nb wiring, 300 mm) · primary ▨ ✅ superconducting QPU supplier fab; KiloFab (Delft) opens 2026 for a claimed 20× capacity increase

evidence: ✅ 4 / 11