Implementation of a quantum metamaterial using superconducting qubits

Abstract

The key issue for the implementation of a metamaterial is to demonstrate the existence of collective modes corresponding to coherent oscillations of the meta-atoms. Atoms of natural materials interact with electromagnetic fields as quantum two-level systems. Artificial quantum two-level systems can be made, for example, using superconducting nonlinear resonators cooled down to their ground state. Here we perform an experiment in which 20 of these quantum meta-atoms, so-called flux qubits, are embedded into a microwave resonator. We observe the dispersive shift of the resonator frequency imposed by the qubit metamaterial and the collective resonant coupling of eight qubits. The realized prototype represents a mesoscopic limit of naturally occurring spin ensembles and as such we demonstrate the AC-Zeeman shift of a resonant qubit ensemble. The studied system constitutes the implementation of a basic quantum metamaterial in the sense that many artificial atoms are coupled collectively to the quantized mode of a photon field.

Multistability and switching in a superconducting metamaterial

“…In the quantum limit, efforts to build many-qubit systems blur the border between circuit quantum electrodynamics and metamaterials [5][6][7][8] while even the classical case holds a multitude of interesting and yet unexplored possibilities. Implementations of these structures, for instance in the form of parametric amplifiers 9 , have already attracted a great deal of attention and continue to do so as the field of superconducting metamaterials evolves.…”

Измерение Параметров Сверхпроводникового Потокового Кубита В Квазидисперсионном Режиме

“…Здесь важно отметить, что, в отличие от обычных атомов, величиной энергети-ческой щели СПК сравнительно легко управлять с помо-щью внешнего магнитного поля, приложенного к петле кубита. Другой важной особенностью, которая отличает СПК от обычных атомов, является то, что, вследствие технологического разброса параметров, СПК в принципе не идентичны, что следует учитывать при создании на их основе квантовых твердотельных метаматериалов [4]. …”

Wide-band tuneability, nonlinear transmission, and dynamic multistability in SQUID metamaterials

“…Their operation frequency spans a huge range, from zero [51,52,53,54] to microwaves [55,18,56,19,32] and to Terahertz [11,12,37,57,38,39,40,15,58,59,41,42] and visible [45] frequencies. Moreover, researchers rely on particular superconducting devices to access the trully quantum metamaterial regime [30,60,61,62,63].…”