Majorana 2

Raveh Neeman

doi:10.5281/zenodo.22674814

Microsoft · topological · CONTESTED (parity measurements only; no qubit operation shown) (2 Jun 2026) · qubits not published · access: lab-only; qubits on Majorana 2 provided to DARPA for independent testing, with on-site access at Microsoft's Maryland research centre (22 Sep 2026)

architecture: Topological — tetron (Majorana) · Open on the map

Register profile — the machine's variant of its architecture

qubit type: Majorana parity in InAs/InAsSb–Pb hybrid-nanowire tetrons

gate mechanism: measurement-based operations by parity measurement (Microsoft's design); none shown — Z-type parity measurements only, no X measurement

connectivity: tetron array (intent)

control: baseband gate voltages

control placement: baseband

readout: interferometric single-shot parity via the quantum capacitance of a quantum dot coupled to the hybrid nanowire

gate evidence: no published figure

flags: contested, not a qubit

Technologies by layer — the machine's cell per layer

1 Qubit carrier	Majorana parity (InAs–Pb tetron) · primary ▤ Abstract (InAs–Pb tetron device; multi-tetron array) ✅ InAs–Pb tetron in a multi-tetron array; lead replaces aluminium for a larger gap
2 Encoding	Fermion-parity encoding (tetron) · primary ▤ Abstract ✅ fermion parity of the tetron hybrid nanowires; parity switching time ~20 s
3 Gate mechanism	Measurement-based Majorana gate · primary ▥ 'Measurement-based operations are executed by determining the parity of topoconductor wires' ✅ measurement-based operations by parity measurement (Microsoft's design); none shown — Z-type parity measurements only, no X measurement
4 Connectivity / transport	Static nearest-neighbour lattice · primary ▥ 🔎 multi-tetron 'four-qubit array' (intent); joint two-qubit parity measurement described, not shown
5 Control	Baseband electrical control (spins, Majorana) · primary ◌ 🔎 baseband gate-voltage control (topological line); not described for Majorana 2
6 Readout	rf quantum-capacitance parity readout · primary ▤ Abstract ✅ interferometric single-shot parity readout from quantum-capacitance shifts of a quantum dot in an interference loop
7 Code	— none — nothing in this layer ▨ 🔎 no code run; no qubit operation shown
8 Decoder	— none — nothing in this layer ◌ 🔎 no decoder
9 Interconnect	— none — nothing in this layer ◌ 🔎 single device, no interconnect
10 Manufacturing	III-V MBE heterostructures (InAs–Pb wires, QD sources) · primary ▥ 'new material stack … consists of lead atop a composite quantum well' ✅ lead on a composite InAs/InAsSb quantum well (new material stack)

evidence: ✅ 5 / 10