Nonlocal quasiparticle transport in normal-superconductor-normal (NSN) hybrid structures probes sub-gap states in the proximity region and is especially attractive in the context of Majorana research. Conductance measurement provides only partial information about nonlocal response composed from both electron-like and hole-like quasiparticle excitations. In this work, we show how a nonlocal shot noise measurement delivers a missing puzzle piece in NSN InAs nanowire-based devices. We demonstrate that in a trivial superconducting phase quasiparticle response is practically charge-neutral, dominated by the heat transport component with a thermal conductance being on the order of conductance quantum. This is qualitatively explained by numerous Andreev reflections of a diffusing quasiparticle, that makes its charge completely uncertain. Consistently, strong fluctuations and sign reversal are observed in the sub-gap nonlocal conductance, including occasional Andreev rectification signals. Our results prove conductance and noise as complementary measurements to characterize quasiparticle transport in superconducting proximity devices.

正常-超导体-正常 (NSN) 混合结构中的非局部准粒子传输探测邻近区域的子间隙状态，在 Majorana 研究的背景下特别有吸引力。电导测量仅提供有关由类电子和类空穴准粒子激发组成的非局部响应的部分信息。在这项工作中，我们展示了非局部散粒噪声测量如何在基于 NSN InAs 纳米线的设备中提供丢失的拼图。我们证明，在微不足道的超导相中，准粒子响应实际上是电荷中性的，由热传输分量主导，热导率处于电导量子的数量级。这可以通过扩散准粒子的无数安德列夫反射来定性地解释，这使得它的电荷完全不确定。一贯地，在子间隙非局部电导中观察到强烈的波动和符号反转，包括偶尔的 Andreev 整流信号。我们的结果证明了电导和噪声是表征超导接近器件中准粒子传输的互补测量。