An international team led by QuTech has demonstrated a three-site Kitaev chain built from quantum dots in a hybrid InSb/Al nanowire. Compared to two-site versions, the extended device showed significantly improved stability of zero-energy Majorana modes (MZMs), attributed to suppressed mode overlap and reduced sensitivity to local perturbations. The chain satisfies key conditions of the Kitaev model, with spinless fermions coupled through superconducting pairing and electron hopping.
Fabrication involved electrostatic gating to define three quantum dots, which were coupled via superconducting segments to emulate a topological chain. Earlier results from two-site configurations exhibited unstable MZMs, dubbed “poor man’s Majoranas.” By scaling to three sites and maintaining consistent performance across devices, the team showed that mode splitting becomes less sensitive to gate noise, marking an intermediate step toward fault-tolerant Majorana qubits.
Although not yet fully topologically protected, the system represents a viable step toward scalable Majorana-based qubits. Simulations suggest that further scaling to five or six sites could achieve coherence times on the order of milliseconds—approaching thresholds needed for fault-tolerant topological quantum computing.
Read more in the official news release here, the peer-reviewed article here, and PubMed record here.
April 4, 2025
