Flux Exclusion Superconducting Quantum Metamaterial: Towards Quantum-level Switching

Abstract

Nonlinear and switchable metamaterials achieved by artificial structuring on the subwavelength scale have become a central topic in photonics research. Switching with only a few quanta of excitation per metamolecule, metamaterial's elementary building block, is the ultimate goal, achieving which will open new opportunities for energy efficient signal handling and quantum information processing. Recently, arrays of Josephson junction devices have been proposed as a possible solution. However, they require extremely high levels of nanofabrication. Here we introduce a new quantum superconducting metamaterial which exploits the magnetic flux quantization for switching. It does not contain Josephson junctions, making it simple to fabricate and scale into large arrays. The metamaterial was manufactured from a high-temperature superconductor and characterized in the low intensity regime, providing the first observation of the quantum phenomenon of flux exclusion affecting the far-field electromagnetic properties of the metamaterial.

Realization and Modeling of Metamaterials Made of rf Superconducting Quantum-Interference Devices

“…However, the insertion of magnetic flux into superconducting materials is often too slow and too dissipative for tuning applications; a low-dissipation quantum effect would be better. For example, flux quantization could be used to discretely tune a superconducting meta-atom [47]. The addition of the Josephson effect to superconducting metamaterials adds a mechanism of tunability that offers a large degree of high-speed tunability and low dissipation.…”

Metaphotonics: An emerging field with opportunities and challenges

“…Magnetic flux quantization was also employed for switching in a quantum superconducting metamaterial. 463 A nonlinear metamaterial containing superconducting Nb thin film was shown to be switchable by controlling the power of the incident beam. 464 The extraordinary properties of graphene have been attracting attention of the metaphotonics community for some time.…”

Metamaterials at the University of Southampton and beyond

“…Our further work included the demonstration of a frequency-selective, energyharvesting, sub-THz superconducting bolometer using 'coherent metamaterials' [46], and a sub-THz electro-optical modulator based on a niobium superconducting metamaterial, where current passing through a network of superconducting metamolecules controls the state of superconductivity [47]. We also explored the idea of flux-exclusion quantum metamaterials [48]. However, perhaps the most relevant illustration of what it is possible to achieve with a highly sensitive state of superconductivity is our superconducting, sub-THz nonlinear metamaterial that operates in the CW regime.…”