Comment on "Interferometric single-shot parity measurement in InAs-Al hybrid devices", Microsoft Quantum, Nature 638, 651-655 (2025)

We consider the 'parity readout' of a (topological) superconductor claimed in Nature 638, 651-655 (2025). A prerequisite for this claim is the existence of a superconducting gap in the nanowire device. However, to determine the presence of a gap, Nature 638, 651-655 (2025) relied on the so-called topological gap protocol (TGP). Here, we show that the TGP can report the regions where the 'parity readout' occurred as either gapped or gapless, depending on data parameters such as magnetic field range and cutter pair (junction transparency). Compounding these issues are inaccuracies in the presented TGP outcomes, which limited investigation of reproducibility. Since these inconsistent outcomes demonstrate that the TGP is not a reliable diagnostic tool for the presence of a superconducting gap, we instead investigate the conductance data for the studied regions -- data that were not presented in Nature 638, 651-655 (2025), but are in the public data repository. These conductance data show that the regions where 'parity readout' occurred are in fact highly disordered and present no clear gap in the nanowire, i.e., the underlying conductance data show that these regions are indeed gapless. That these regions are gapless contradicts the claim that the reported measurements are of the parity of a superconducting nanowire, let alone the parity of a topological superconducting nanowire. Taken together, these issues mean that the core findings in Nature 638, 651-655 (2025) are not reliable and should be revisited.