Interacting Few Level Systems at the Atomic Scale

扫描隧道显微镜（STM）在毫开尔文（mK）温度下工作时具有原子精度和出色的能量分辨率，在传感和材料科学领域发挥了重要的支持技术作用。然而，到目前为止，它还不能直接访问目标几个级别系统中的量子相干性的属性，这可以以不同的方式表现出来。我们将表征，理论上描述，并进一步开发一个STM尖端功能化与一个单一的量子态以及保护内的超导间隙，这是非常尖锐的能量。更具体地说，磁性杂质被添加到STM尖端的顶点，以诱导束缚的带隙Yu-Shiba-Rusinov（YSR）状态。这种状态是一个多体系统的集体状态，其寿命仅受与剩余环境自由度相互作用的限制。我们的总体目标是了解这样的STM尖端状态耦合到目标几个层次的系统，超导主机，和他们的周围环境。我们希望直接访问由此产生的多体量子系统的相干特性，并实现相干操纵方案。此外，我们想探索的独特功能的YSR-STM作为手段来感知奇异的量子态。我们的团队是实验和理论之间的良好合作，有着广泛的联合出版记录。它汇集了mK-STM的物理和实验技术方面的丰富专业知识以及介观器件中超导量子传输的理论专业知识。

The scanning tunneling microscope (STM) has played an important role as a supporting technology in the context of sensing and material science with its atomic precision and excellent resolution in energy when operated at milli-Kelvin (mK) temperatures. However, it has until now not been able to directly access the properties of quantum coherence in target few level systems, which can manifest in different ways. We will characterize, theoretically describe, and further develop an STM tip functionalized with a single quantum state well-protected inside a superconducting gap, which is extremely sharp in energy. More specifically, a magnetic impurity is added to the apex of the STM tip to induce a bound in-gap Yu-Shiba-Rusinov (YSR) state. This state is a collective state in a correlated many-body system with a lifetime only limited by interactions with residual environmental degrees of freedom. Our general goal is to understand such an STM tip state coupled to target few level systems, to the superconducting hosts, and their surrounding environment. We want to directly access coherence properties of the resulting many-body quantum system and implement coherent manipulation schemes. Furthermore, we want to explore the unique features of the YSR-STM as means for sensing exotic quantum states. Our team is a well-established collaboration between experiment and theory, with an extensive record of joint publications. It brings together vast expertise in the physics and experimental techniques of mK-STM and theoretical expertise in superconducting quantum transport in mesoscopic devices.