标题： $ΔT$-多终端混合系统中的噪声 显示英文标题

标题： $ΔT$-noise in Multiterminal Hybrid Systems

摘要： 研究电荷电流涨落（噪声）可以为纳米尺度系统的特性提供有用的见解。 在本工作中，探索了多端点混合正常-超导系统在热非平衡状态下的噪声特殊性质，即当存在温度偏置时（$\Delta T$-噪声）。 使用Landauer-Büttiker方法，我们识别出两个贡献：背景噪声和过量噪声，并在同时施加电和热偏置时分析它们。 当存在温度偏置且超导端点接地时，我们发现第一个贡献不仅取决于电导率，如平衡状态下的Johnson-Nyquist噪声，还取决于与热导率严格相关的量。 这是我们的第一个主要结果。 另一方面，第二个贡献显示出预期的附加项，这些项来源于电流在不同传输通道中的分束，包括与Andreev反射过程相关的项。 然而，由温度差引起的噪声还揭示了干涉项，这些项在电压偏置或没有任何Andreev过程的情况下不可能存在。 最后，我们将所得结果应用于两种不同的具体物理情况。 第一种是一个通用的三端点正常-超导体-正常系统，第二种是一个基于整数量子霍尔效应区域中自旋分辨的共向手性通道的器件，其中包含一个超导区域。 在这些示例设置中，我们主要研究当施加高电压或高温偏置时的散粒噪声区域。 我们发现这两个极限之间存在显著差异，这最终表明了电学和热学引起的电荷电流涨落的不同性质。 显示英文摘要

摘要： The study of charge current fluctuations (noise) can give useful insights into the properties of nanoscale systems. In this work, the peculiar properties of noise in multiterminal hybrid normal-superconducting systems are explored in the thermal out-of-equilibrium regime, i.e., when temperature biases are present ($\Delta T$-noise). Using the Landauer-B\"uttiker approach, we identify two contributions: background noise and excess noise, analyzing them when both electrical and thermal biases are applied. When temperature biases are present, and superconducting terminals are grounded, we find that the first contribution depends not only on the electrical conductance, as the Johnson-Nyquist at equilibrium, but also on a quantity strictly related to the heat conductance. This is our first main result. On the other hand, the second contribution shows, as expected, additional terms originating from the partitioning of currents into different transport channels, including the ones associated with Andreev reflection processes. However, noise induced by the temperature differences unveil also interference terms that cannot be present either in voltage bias or in the absence of any Andreev processes. Finally, we apply the results obtained to two different specific physical situations. The first is a generic three-terminal normal-superconductor-normal system, and the second is a device based on spin-resolved co-propagating chiral channels in the integer quantum Hall regime with a superconducting region. In these example setups, we investigate mainly the shot-noise regimes, when high-voltage or high-temperature biases are applied. We find remarkable differences between the two limits, which ultimately show the different nature of electrically and thermally induced charge current fluctuations.