Waveguide bandgap engineering with an array of superconducting qubits
Waveguide bandgap engineering with an array of superconducting qubits
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DOI：
10.1038/s41535-021-00310-z
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发表时间：
2020-06
影响因子：
5.7
通讯作者：
J. Brehm;A. Poddubny;A. Stehli;T. Wolz;H. Rotzinger;A. Ustinov
中科院分区：
文献类型：
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作者：
J. Brehm;A. Poddubny;A. Stehli;T. Wolz;H. Rotzinger;A. Ustinov
波导量子电动力学为通过一维开放波导有效地设计人造原子之间的相互作用提供了广泛的可能性。虽然这些相互作用已经在几个量子比特的限制下进行了实验研究，但到目前为止，对于超材料配置中更大的量子比特阵列，这些系统的集体性质还没有得到解决。在这里，我们实验研究了一种由八个超导跨声子量子比特组成的超材料，这种量子比特具有局域频率控制，耦合到波导的模式连续谱上。通过连续地将量子比特调谐到一个共同的共振频率，我们观察到了超辐射态和亚辐射态的形成，以及极化子带隙的出现。利用量子比特的量子非线性，我们通过在系综的带隙区域引入一个透明窗口来展示对后者的控制。这项工作的电路将单量子比特和双量子比特的实验扩展到完全成熟的量子超材料，从而为超导波导量子电动力学的大规模应用铺平了道路。
Waveguide quantum electrodynamics offers a wide range of possibilities to effectively engineer interactions between artificial atoms via a one-dimensional open waveguide. While these interactions have been experimentally studied in the few qubit limit, the collective properties of such systems for larger arrays of qubits in a metamaterial configuration has so far not been addressed. Here, we experimentally study a metamaterial made of eight superconducting transmon qubits with local frequency control coupled to the mode continuum of a waveguide. By consecutively tuning the qubits to a common resonance frequency we observe the formation of super- and subradiant states, as well as the emergence of a polaritonic bandgap. Making use of the qubits quantum nonlinearity, we demonstrate control over the latter by inducing a transparency window in the bandgap region of the ensemble. The circuit of this work extends experiments with one and two qubits toward a full-blown quantum metamaterial, thus paving the way for large-scale applications in superconducting waveguide quantum electrodynamics.