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arXiv · 2006.03330

Waveguide Bandgap Engineering with an Array of Superconducting Qubits

Jan David Brehm·Alexander N. Poddubny·Alexander Stehli·Tim Wolz·Hannes Rotzinger·Alexey V. Ustinov
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Abstract

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 towards a full-blown quantum metamaterial, thus paving the way for large-scale applications in superconducting waveguide quantum electrodynamics.

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Jan David Brehm, Alexander N. Poddubny, Alexander Stehli, Tim Wolz, Hannes Rotzinger, Alexey V. Ustinov. 2020-06-05. Waveguide Bandgap Engineering with an Array of Superconducting Qubits. https://doi.org/10.1038/s41535-021-00310-z

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