近日，法国格勒诺布尔大学的C.Chapelier课题组研究了超导纳米线中高能准粒子的热化和动力学。相关成果已于2023年3月30日在国际学术期刊《自然—物理学》上发表。

该研究团队采用自主开发的扫描临界电流显微技术，利用低温扫描隧道显微镜分别通过偏置电压和隧道电流调节准粒子注入的能量和速率。研究人员观察到高能准粒子注入后纳米线临界电流的降低，结果表明临界电流降低的主要由注入功率控制，注入速率对其影响较小。这一发现证明了临界电流降低的热机制，并揭示了产生热点的快速动力学。

研究人员表示，超导纳米结构中能量准粒子的弛豫涉及电子、声子和库珀对之间的多级相互作用。这些动力学对于量子比特或光子探测器等器件的性能至关重要。然而，由于这些相互作用需要对准粒子进行控制注入的实验，因此仍不为人所理解。到目前为止，此类实验通常采用具有固定隧道屏障的固态隧道结。

附：英文原文

Title: Thermalization and dynamics of high-energy quasiparticles in a superconducting nanowire

Author: Jalabert, T., Driessen, E. F. C., Gustavo, F., Thomassin, J. L., Levy-Bertrand, F., Chapelier, C.

Issue&Volume: 2023-03-30

Abstract: The relaxation of energetic quasiparticles in superconducting nanostructures involves many cascaded interactions between electrons, phonons and Cooper pairs. These dynamics are central to the performance of devices such as qubits or photon detectors. However, they are still not well understood, as they require experiments in which quasiparticles are injected in a controlled fashion. Until now, such experiments have typically employed solid-state tunnel junctions with a fixed tunnel barrier. Here we use instead the scanning critical current microscopy technique that we developed by taking advantage of a cryogenic scanning tunnelling microscope to tune independently the energy and the rate of quasiparticle injection through, respectively, the bias voltage and the tunnelling current. For high-energy quasiparticles, we observe a reduction in the critical current of a nanowire and show it is mainly controlled by the injected power and, marginally, by the injection rate. Our results prove a thermal mechanism for the reduction of the critical current and give insight into the rapid dynamics of the generated hot spot.

DOI: 10.1038/s41567-023-01999-4

Source: https://www.nature.com/articles/s41567-023-01999-4