WACQT quantum computer (Chalmers 25-qubit flip-chip processor)

Raveh Neeman

doi:10.5281/zenodo.22674814

Chalmers University of Technology (WACQT)

WACQT quantum computer (Chalmers 25-qubit flip-chip processor)

Chalmers University of Technology (WACQT) · superconducting circuits · DEMONSTRATED (testbed access for algorithms announced for 2025) (2023-2024) · 25 physical qubits · access: testbed for Swedish industry and academia (Chalmers Next Labs)

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

Register profile — the machine's variant of its architecture

qubit type: fixed-frequency transmon (Xmon)

gate mechanism: parametric CZ and iSWAP via frequency-tunable couplers

connectivity: 25 qubits with 40 frequency-tunable couplers

control: control lines on a separate control chip (flip-chip C-chip)

readout: dispersive, quarter-wavelength resonators

flags: no published error rates

Technologies by layer — the machine's cell per layer

1 Qubit carrier	Transmon · primary ▤ abstract ✅ 25 fixed-frequency transmon (Xmon) qubits on the qubit chip of a flip-chip module
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 ▤ abstract ✅ parametric CZ and iSWAP driven through 40 frequency-tunable couplers
4 Connectivity / transport	Static nearest-neighbour lattice · primary ▤ abstract ✅ static on-chip lattice: 25 qubits joined by 40 tunable couplers
5 Control	Room-temperature electronics + per-qubit coax/flex · primary ◌ 🔎 room-temperature electronics assumed (family); control lines routed on the control chip
6 Readout	Dispersive microwave readout (+TWPA, Purcell) · primary ▤ abstract ✅ dispersive readout via quarter-wavelength resonators
7 Code	— none — nothing in this layer ◌ 🔎 no QEC code run located for the 25-qubit machine
8 Decoder	— none — nothing in this layer ◌ 🔎 no decoder; no QEC run
9 Interconnect	Multi-die packaging in one module (flip-chip, bump-bonded control die) · primary ▤ abstract ✅ two-tier flip-chip module: qubit chip (Q-chip) bonded to a control chip (C-chip); no inter-module link
10 Manufacturing	Superconducting-qubit lithography (Al/AlOx/Al junctions, Nb wiring, 300 mm) · primary ◌ 🔎 superconducting-qubit lithography; Chalmers builds the machine in-house (fab site not stated in the opened sources)

evidence: ✅ 5 / 10