Semiconductor nanowires with proximity-induced superconductivity are leading contenders for manifesting Majorana fermions in condensed matter^1,2,3,4,5. However, unambiguous detection of these quasiparticles is controversial⁶, and one proposed method is to show that the peak in the conductance at zero applied bias is quantized to the value of 2e²/h (refs. ^7,8,9,10). This has been reported previously¹¹, but only by probing one end of the device. Yet, if peaks come from Majorana modes, they should be observed at both ends simultaneously. Here we fabricate devices that feature tunnel probes on both ends of a nanowire and observe peaks that are close to the quantized value. These peaks evolve with the tunnel barrier strength and magnetic field in a way that is consistent with Majorana zero modes. However, we only find nearly quantized zero-bias peaks localized to one end of the nanowire, while conductance dips are observed for the same parameters at the other end. We also identify delocalized states near zero magnetic field and at higher electron density, which is not in the basic Majorana regime. These results enable us to lay out procedures for assessing the non-locality of subgap wavefunctions and provide a classification of nanowire bound states based on their localization.

具有邻近感应超导性的半导体纳米线是在凝聚态^1,2,3,4,5中表现马约拉纳费米子的主要竞争者。然而，这些准粒子的明确检测是有争议的⁶，并且一种建议的方法是表明在零施加偏压处的电导峰值被量化为 2 e ² / h的值（参考文献^{7、8、9、10}） . 此前曾报道过¹¹，但只能通过探测设备的一端。然而，如果峰值来自马约拉纳模式，则应在两端同时观察到它们。在这里，我们制造了在纳米线两端具有隧道探针的设备，并观察到接近量化值的峰值。这些峰值随着隧道势垒强度和磁场以与马约拉纳零模式一致的方式演变。然而，我们仅发现位于纳米线一端的几乎量化的零偏置峰值，而在另一端观察到相同参数的电导下降。我们还确定了接近零磁场和较高电子密度的离域状态，这不在基本的马约拉纳状态中。