Hexagonal boron nitride as a low-loss dielectric for superconducting quantum circuits and qubits-猫眼课题宝

DOI：

10.1038/s41563-021-01187-w

发表时间：

2021-08

期刊：

Nature Materials

影响因子：

41.2

通讯作者：

中科院分区：

材料科学1区

文献类型：

作者：

J. Wang;M. Yamoah;Qing Li;Amir H. Karamlou;T. Dinh;B. Kannan;Jochen Braumueller;David K. Kim;A. Melville;Sarah E. Muschinske;B. Niedzielski;K. Serniak;Youngkyu Sung;R. Winik;J. Yoder;M. Schwartz;Kenji Watanabe;T. Taniguchi;T. Orlando;S. Gustavsson;P. Jarillo-Herrero;W. Oliver

在微波频率下具有低损耗的电介质对于高相干固态量子计算平台是必不可少的。通过测量集成在超导电路中的NbSe 2-hBN-NbSe 2异质结构平行板电容器（PPC）的品质因数，研究了六方氮化硼（hBN）薄膜在微波波段的介电损耗。在低温、单光子状态下，hBN的微波损耗角正切最多在10− 6范围内。我们将hBN PPC与铝约瑟夫森结集成，实现了相干时间达到25 μs的transmon量子比特，与从谐振器测量推断的hBN损耗角正切一致。与传统的全铝共面transmons相比，hBN PPC将量子位特征尺寸减小了大约两个数量级。我们的研究结果确立了hBN作为一种有前途的电介质，用于构建高相干量子电路，其占地面积大大减少，并且具有高能量参与，有助于减少不必要的量子位串扰。

Dielectrics with low loss at microwave frequencies are imperative for high-coherence solid-state quantum computing platforms. Here we study the dielectric loss of hexagonal boron nitride (hBN) thin films in the microwave regime by measuring the quality factor of parallel-plate capacitors (PPCs) made of NbSe2–hBN–NbSe2heterostructures integrated into superconducting circuits. The extracted microwave loss tangent of hBN is bounded to be at most in the mid-10−6range in the low-temperature, single-photon regime. We integrate hBN PPCs with aluminium Josephson junctions to realize transmon qubits with coherence times reaching 25 μs, consistent with the hBN loss tangent inferred from resonator measurements. The hBN PPC reduces the qubit feature size by approximately two orders of magnitude compared with conventional all-aluminium coplanar transmons. Our results establish hBN as a promising dielectric for building high-coherence quantum circuits with substantially reduced footprint and with a high energy participation that helps to reduce unwanted qubit cross-talk.

Hexagonal boron nitride as a low-loss dielectric for superconducting quantum circuits and qubits

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