Reversible modulation of superconductivity in thin-film NbSe2 via plasmon coupling

Abstract

In recent years, lightwave has stood out as an ultrafast, non-contact control knob for developing compact superconducting circuitry. However, the modulation efficiency is limited by the low photoresponse of superconductors. Plasmons, with the advantages of strong light-matter interaction, present a promising route to overcome the limitations. Here we achieve effective modulation of superconductivity in thin-film NbSe₂ via near-field coupling to plasmons in gold nanoparticles. Upon resonant plasmon excitation, the superconductivity of NbSe₂ is substantially suppressed. The modulation factor exceeds 40% at a photon flux of 9.36 × 10¹³s⁻¹mm⁻², and the effect is significantly diminished for thicker NbSe₂ samples. Our observations can be theoretically interpreted by invoking the non-equilibrium electron distribution in NbSe₂ driven by the plasmon-associated evanescent field. Finally, a reversible plasmon-driven superconducting switch is realized in this system. These findings highlight plasmonic tailoring of quantum states as an innovative strategy for superconducting electronics.

Light excitation has been recognized as an appealing tuning knob for superconducting circuits, but usually its efficiency is limited by the low photoresponse of superconductors. Here, the authors demonstrate efficient reversible modulations of superconductivity in thin films of NbSe₂ via near-field coupling to plasmonic Au nanoparticles.