The anomalous low-temperature properties of glasses arise from intrinsic excitable entities, so-called tunneling Two-Level-Systems (TLS), whose microscopic nature has been baffling solid-state physicists for decades. TLS have become particularly important for micro-fabricated quantum devices such as superconducting qubits, where they are a major source of decoherence. Here, we present a method to characterize individual TLS in virtually arbitrary materials deposited as thin films. The material is used as the dielectric in a capacitor that shunts the Josephson junction of a superconducting qubit. In such a hybrid quantum system the qubit serves as an interface to detect and control individual TLS. We demonstrate spectroscopic measurements of TLS resonances, evaluate their coupling to applied strain and DC-electric fields, and find evidence of strong interaction between coherent TLS in the sample material. Our approach opens avenues for quantum material spectroscopy to investigate the structure of tunneling defects and to develop low-loss dielectrics that are urgently required for the advancement of superconducting quantum computers.

玻璃的异常低温特性来自固有的可激发实体，即所谓的隧穿二级系统（TLS），其微观性质一直困扰着固态物理学家数十年。TLS对于微制造的量子设备（例如超导量子位）尤其重要，在量子设备中，TLS是消相干的主要来源。在这里，我们提出了一种方法来表征沉积为薄膜的几乎任意材料中的单个TLS。该材料用作电容器中的电介质，该电容器使超导量子位的约瑟夫森结分流。在这种混合量子系统中，量子位用作检测和控制单个TLS的接口。我们展示了TLS共振的光谱测量，评估了它们与施加的应变和直流电场的耦合，并找到样本材料中相干TLS之间强烈相互作用的证据。我们的方法为量子材料光谱学研究隧道缺陷的结构和开发低损耗电介质开辟了途径，而超导量子计算机的发展迫切需要低损耗电介质。