Resolving the positions of defects in superconducting quantum bits
Resolving the positions of defects in superconducting quantum bits
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DOI：
10.1038/s41598-020-59749-y
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发表时间：
2020-02-20
影响因子：
4.6
通讯作者：
Lisenfeld, Juergen
中科院分区：
文献类型：
--
作者：
Bilmes, Alexander;Megrant, Anthony;Lisenfeld, Juergen
固态量子相干器件正在迅速发展。例如，超导电路已经被用于演示包含几十个量子比特的原型量子处理器。这一发展还揭示了这种器件中的退相干和能量损失的主要部分源于寄生材料缺陷的浴。然而，无论是缺陷的微观结构，也不了解它们在样品制造过程中出现的机制。在这里，我们提出了一种技术，以获得相对于量子位电路的薄膜边缘的缺陷的位置上的信息。缺陷的共振频率通过将量子位样本暴露于由芯片周围的电极产生的电场来调谐。通过确定每个电极的缺陷的耦合强度，并将其与场分布的模拟进行比较，我们获得了缺陷位于哪个位置和哪个界面的概率。这种方法适用于各种量子位类型的现有样本，而无需进一步的片上设计更改。它提供了一个有价值的工具，以改善材料质量和纳米制造过程，朝着更相干的量子电路。
Solid-state quantum coherent devices are quickly progressing. Superconducting circuits, for instance, have already been used to demonstrate prototype quantum processors comprising a few tens of quantum bits. This development also revealed that a major part of decoherence and energy loss in such devices originates from a bath of parasitic material defects. However, neither the microscopic structure of defects nor the mechanisms by which they emerge during sample fabrication are understood. Here, we present a technique to obtain information on locations of defects relative to the thin film edge of the qubit circuit. Resonance frequencies of defects are tuned by exposing the qubit sample to electric fields generated by electrodes surrounding the chip. By determining the defect's coupling strength to each electrode and comparing it to a simulation of the field distribution, we obtain the probability at which location and at which interface the defect resides. This method is applicable to already existing samples of various qubit types, without further on-chip design changes. It provides a valuable tool for improving the material quality and nano-fabrication procedures towards more coherent quantum circuits.