Noise within solid-state systems at low temperatures can typically be traced back to material defects. In amorphous materials, these defects are broadly described by the tunneling two-level systems (TLSs) model. TLS have recently taken on further relevance in quantum computing because they dominate the coherence limit of superconducting quantum circuits. Efforts to mitigate TLS impacts have thus far focused on circuit design, material selection, and surface treatments. Our work takes an approach that directly modifies TLS properties. This is achieved by creating an acoustic bandgap that suppresses all microwave-frequency phonons around the operating frequency of a transmon qubit. For embedded TLS strongly coupled to the transmon qubit, we measure a pronounced increase in relaxation time by two orders of magnitude, with the longest T 1 time exceeding 5 milliseconds. Our work opens avenues for studying the physics of highly coherent TLS and methods for mitigating noise within solid-state quantum devices.

中文翻译：

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超导量子电路中原子级缺陷的声子工程


固态系统在低温下的噪声通常可以追溯到材料缺陷。在非晶态材料中，这些缺陷由隧道两能系统 （TLS） 模型广泛描述。TLS 最近在量子计算中具有进一步的重要性，因为它们主导着超导量子电路的相干极限。迄今为止，减轻 TLS 影响的努力主要集中在电路设计、材料选择和表面处理上。我们的工作采用了一种直接修改 TLS 属性的方法。这是通过产生一个声学带隙来实现的，该带隙抑制了 transmon 量子比特工作频率附近的所有微波频率声子。对于与 transmon 量子比特强耦合的嵌入式 TLS，我们测量的弛豫时间显着增加了两个数量级，最长的 T1 时间超过 5 毫秒。我们的工作为研究高度相干 TLS 的物理学和减轻固态量子器件内噪声的方法开辟了途径。