High T_c Superconducting THz Metamaterial for Ultrastrong Coupling in a Magnetic Field

Abstract

We fabricate high temperature superconducting metasurfaces from yttrium–barium–copper oxide (YBCO) films via focused ion beam milling. The design of the complementary split ring resonators yields a high quality factor (up to Q = 31) resonance, which is fully switchable when exploiting the transition from the superconducting to normal conducting state, which is achieved by heating the sample above the critical temperature. Meanwhile, the resonance is continuously visible and frequency stable under the action of a magnetic field, up to B = 9 T. This makes it an ideal candidate for light–matter coupling experiments with magnetic field tunable Landau level transitions. We present two techniques to bring the metasurface in close vicinity of a 2D electron gas in an AlGaAs/GaAs QW without direct deposition, and we achieve a normalized vacuum Rabi frequency of ΩR/ωcyc = 24%.

Dynamic Terahertz Plasmonics Enabled by Phase‐Change Materials

“…Among the earlier reports utilizing classical [100][101][102][103][104][105][106][107][108][109][110][111][112][113][114][115][116][117][118][119] or high transition temperature (T c ) superconductors [120][121][122][123][124][125][126][127][128][129][130][131][132][133][134][135] for THz metamaterial design, we briefly review a few selected works employing three different types of superconductors, i.e., yttrium barium copper oxide (YBCO), Nb, and NbN, with their functionalities based on external variables and the nonlinear phenomena. While VO 2 has been utilized for both a film-type THz modulation medium and subwavelength structures to adjust the electromagnetic properties, superconductors have mainly been investigated to improve the performance of metallic structures as metamaterials.…”

“…[101,111,134] The Nb-based metamaterial displayed www.advopticalmat.de in Figure 14a presents three resonance frequencies in its simulated THz transmission spectrum (Figure 14b). [101,111,134] The Nb-based metamaterial displayed www.advopticalmat.de in Figure 14a presents three resonance frequencies in its simulated THz transmission spectrum (Figure 14b).…”

“…[134] Recently, the resonance of a YBCO-based metamaterial was reported to still be observable under an external magnetic field as high as 9 T below the critical temperature. [134] Recently, the resonance of a YBCO-based metamaterial was reported to still be observable under an external magnetic field as high as 9 T below the critical temperature.…”

“…[142][143][144][145][146][147] In this section, a few pioneering reports about active THz plasmonics based Adv. [134] Copyright 2018, American Chemical Society. 2020, 8,1900548 The thickness of the sapphire substrate is 500 µm.…”

“…Furthermore, the inherent change due to external stimuli, such as temperature, magnetic field, and electric bias, enables tuning of the electromagnetic properties of THz waves. Among the earlier reports utilizing classical [100][101][102][103][104][105][106][107][108][109][110][111][112][113][114][115][116][117][118][119] or high transition temperature (T c ) superconductors [120][121][122][123][124][125][126][127][128][129][130][131][132][133][134][135] for THz metamaterial design, we briefly review a few selected works employing three different types of superconductors, i.e., yttrium barium copper oxide (YBCO), Nb, and NbN, with their functionalities based on external variables and the nonlinear phenomena.…”