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Title: Has a semiconductor nanowire reached the topological superconducting phase
Plain: Many experiments on superconductor-coated semiconductor wires saw signals expected from Majorana modes, but ordinary bound states caused by disorder give similar signals, so it is unproven that any wire has become topological.
Precise: For InAs-Al or InSb-Al hybrid nanowires in a parallel magnetic field, establish whether a topological phase exists: bulk gap closing and reopening at Zeeman energy $E_Z = \sqrt{\Delta^2 + \mu^2}$, with zero-bias conductance peaks at both ends whose splitting decays exponentially with wire length. An answer is yes or no, based on three-terminal data passing pre-registered criteria that disorder simulations show trivial states cannot pass.
Settled by: Three-terminal nonlocal conductance showing gap reopening and end-to-end correlated zero modes, reproduced across devices with data and analysis code released.
Kind: well-posed
Answer type: yes-no
References: (empty)
Literature status: contested
Status note: Microsoft's topological-gap-protocol devices (Phys. Rev. B 107, 245423, 2023) were challenged in a 2025 comment (arXiv:2502.19560) arguing that the protocol outcome depends on analysis choices.
Posed since: 2010