Microscopic two-level system (TLS) defects at dielectric surfaces and interfaces are among the dominant sources of loss in superconducting quantum circuits, and their properties have been extensively probed using superconducting resonators and qubits. We report on spectroscopy of TLSs coupling to the strain field in a surface acoustic wave (SAW) resonator. The narrow free spectral range of the resonator allows for two-tone spectroscopy where a strong pump is applied at one resonance, while a weak signal is used to probe a different mode. We map the spectral hole burnt by the pump tone as a function of frequency and extract parameters of the TLS ensemble. Our results suggest that detuned acoustic pumping can be used to enhance the coherence of superconducting devices by saturating TLSs.

介电表面和界面处的微观两级系统（TLS）缺陷是超导量子电路损耗的主要来源，其特性已使用超导谐振器和量子位进行了广泛探测。我们报道了在表面声波（SAW）谐振器中耦合到应变场的TLS的光谱学。谐振器的窄自由光谱范围允许进行两声光谱，其中在一个谐振处施加一个强泵浦，而一个弱信号则用于探测不同的模式。我们将泵浦音燃烧的频谱孔映射为频率的函数，并提取TLS集成的参数。我们的结果表明，通过使TLS饱和，可以使用失谐声泵浦来增强超导设备的相干性。