QSCOUT (Quantum Scientific Computing Open User Testbed)

Raveh Neeman

doi:10.5281/zenodo.22674814

Sandia National Laboratories · trapped ions · DEPLOYED (open user testbed; discontinuation scheduled for end of FY2026, 30 Sep 2026, now past; no end notice on the Sandia page) (2021-2026) · 6 physical qubits · access: open user testbed (DOE-funded; calls for proposals); after the DOE funding redirection only a few short user projects until the end of FY2026

architecture: Trapped ions — linear Paul trap with individual laser addressing · Open on the map

Register profile — the machine's variant of its architecture

qubit type: hyperfine clock-state qubit (171Yb+)

gate mechanism: Raman transitions with a 355 nm pulsed laser; Molmer-Sorensen 2Q gates

connectivity: linear ion chain, all-to-all

control: individual addressing by imaging an AOM array onto the chain; pulse-level access (Jaqal)

control placement: room-temp + free-space optics

readout: fluorescence: chain imaged onto a multimode-fibre array with individual photomultiplier tubes

gate evidence: no published figure

Technologies by layer — the machine's cell per layer

1 Qubit carrier	Trapped atomic ion · primary ▦ ✅ 171Yb+ ions in a linear chain, 6 qubits
2 Encoding	Hyperfine / clock-state qubit · primary ▦ ✅ qubits encoded in the hyperfine clock states of each 171Yb+ ion
3 Gate mechanism	Mølmer–Sørensen / light-shift laser gate · primary ▦ ✅ Molmer-Sorensen 2Q gates via 355 nm pulsed-laser Raman transitions; fidelity ~0.95-0.99
4 Connectivity / transport	Ion-chain motional bus (all-to-all in chain) · primary ▦ ✅ linear ion chain with all-to-all connectivity
5 Control	Free-space laser addressing of ions (AOM/AOD beams) · primary ▦ ✅ individual addressing by imaging an AOM array onto the ion chain; pulse-level user access
6 Readout	Fluorescence state detection (ions, defects) · primary ▦ ✅ fluorescence detection: chain imaged onto multimode fibres feeding individual PMTs
7 Code	— none — nothing in this layer ◌ 🔎 no QEC code as a machine feature; open testbed for user experiments
8 Decoder	— none — nothing in this layer ◌ 🔎 no decoder
9 Interconnect	— none — nothing in this layer ◌ 🔎 single surface trap; no interconnect
10 Manufacturing	Ion-trap fabrication (surface-electrode chips; machined 3D blade traps) · primary ▦ ✅ Sandia-fabricated surface ion trap with wide optical access

evidence: ✅ 7 / 10