We report the experimental realization of a 3D capacitively-shunt superconducting flux qubit with long coherence times. At the optimal flux bias point, the qubit demonstrates energy relaxation times in the 60-90 $\mu$s range, and Hahn-echo coherence time of about 80 $\mu$s which can be further improved by dynamical decoupling. Qubit energy relaxation can be attributed to quasiparticle tunneling, while qubit dephasing is caused by flux noise away from the optimal point. Our results show that 3D c-shunt flux qubits demonstrate improved performance over other types of flux qubits which is advantageous for applications such as quantum magnetometry and spin sensing.

中文翻译：

---

嵌入 3D 腔的长寿命电容分流通量量子位

我们报告了具有长相干时间的 3D 电容分流超导通量量子位的实验实现。在最佳通量偏置点，量子位表现出 60-90 $\mu$s 范围内的能量弛豫时间，以及大约 80 $\mu$s 的 Hahn-echo 相干时间，这可以通过动态去耦进一步改善。量子位能量弛豫可归因于准粒子隧穿，而量子位相移是由远离最佳点的通量噪声引起的。我们的结果表明，3D c-shunt 通量量子位表现出优于其他类型通量量子位的性能，这对于量子磁力计和自旋传感等应用是有利的。