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

Abstract

Funding for Open Access provided by the UMD Libraries Open Access Publishing Fund.We have prepared meta-atoms based on radio-frequency superconducting quantum-interference devices (rf SQUIDs) and examined their tunability with dc magnetic field, rf current, and temperature. rf SQUIDs are superconducting split-ring resonators in which the usual capacitance is supplemented with a Josephson junction, which introduces strong nonlinearity in the rf properties. We find excellent agreement between the data and a model that regards the Josephson junction as the resistively and capacitively shunted junction. A magnetic field tunability of 80 THz=G at 12 GHz is observed, a total tunability of 56% is achieved, and a unique electromagnetically induced transparency feature at intermediate excitation powers is demonstrated for the first time. An rf SQUID metamaterial is shown to have qualitatively the same behavior as a single rf SQUID with regard to dc flux and temperature tuning.This work is supported by the NSF-GOALI Program through Grant No. ECCS-1158644 and the Center for Nanophysics and Advanced Materials (CNAM). Funding for Open Access was provided by the UMD Libraries Open Access Publishing Fund

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

“…However, for any other value of the dc flux, that band shifts downwards, down to a minimum attained for dc flux bias equal to odd semi-integer multiples of Φ 0 . This procedure results in a very clear pattern of periodic shifting of the linear band with the dc flux bias, which has been observed in experiments [19,32,24]. Here the basic features of the dc flux tuneability patterns are reproduced by integrating equations (1) and using the calculated fluxes φ n,m and voltageṡ φ n,m to obtain the averaged energy per period of the ac field (9) and (10) as a function of the frequency of the ac field Ω and the dc flux φ dc .…”

“…The replacement of metallic SRRs with rf SQUIDs, which have no direct electrical conduct but instead they are coupled magnetically through their mutual inductances, has been suggested theoretically a few years ago [30,31]. Such SQUID metamaterials have been recently realized in the lab [18,19,32,24,25], that exhibit strong nonlinearities and wide-band tuneability with unusual magnetic properties due to macroscopic quantum effects. Nonlinearity and discreteness in SQUID metamaterials, along with low Ohmic losses (at least at microwave frequencies) may also lead in the generation of discrete breathers [33,34,35], i.e., time-periodic and spatially localized modes that change locally the magnetic response.…”

“…Superconducting metamaterials, resulting either from bare replacement of the metallic parts employed in conventional metamaterials by superconducting ones [37,12,11,38,39,40,41,42], or by constructing hybrid structures comprising superconducting components [43,44,45,46,47,48,14,49], or even by incoprorating the Josephson effect as in arrays of SQUIDs [50,18,19,32,24], have been already proposed and/or demonstrated experimentally. 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.…”

“…It consists of a superconducting ring interrupted by a Josephson junction (JJ) Josephson junction (JJ) [21], as shown schematically in figure 1(a). The SQUID is a strongly nonlinear resonator [22,23], that is tuneable over a wide frequency range by applying either a flux bias [18,24] or by varying the incoming rf power of an applied alternating field [24,25]. This superconducting device has found up to date numerous applications [26,27,28,29], and it is known to be the worlds most sensitive detector of magnetic signals.…”

Giant nonlinearity in a superconducting sub-terahertz metamaterial

“…Before proceeding, we will briefly overview the properties that make the superconducting metamaterials particularly well-suited for operation at frequencies up to and including terahertz. 17 The superconducting metamaterials offer low Joule losses, sub-nanosecond nonlinear response, [18][19][20] access to quantum-mechanical phenomena through the inclusion of Josephson junctions, [21][22][23] and sensitivity to light, 24 magnetic field, and temperature. 7,25,26 The nonlinear response of the superconductors at terahertz/sub-THz frequencies occurs via two mechanisms.…”