Optical and TeraHertz radiation methods of flux manipulation in superconductors

Résumé :

Although the average properties of vortex matter in superconductors can be tuned using magnetic fields, temperature, or electric currents, the manipulation of individual Abrikosov vortices remains challenging and has only been demonstrated with advanced scanning local probe microscopies. Recently, a far-field optical method was proposed, leveraging local heating of the superconductor with a focused laser beam to enable fast and precise manipulation of individual vortices, akin to optical tweezers. This development paves the way for creating laser-driven Josephson junctions controlled by optically driven Abrikosov vortices.

Another approach for manipulating single flux quanta involves the so-called inverse Faraday effect, where circularly polarized radiation interacts with the superconducting condensate, acting as an effective magnetic field that generates supercurrents and DC magnetic moments. By employing the time-dependent Ginzburg–Landau equation formalism, we have analyzed the current-carrying states of a small superconducting ring illuminated by such radiation. Numerical simulations reveal the possibility of 100% on-demand switching between current-carrying states in the superconductor by controlling the helicity of the electromagnetic field polarization.

Furthermore, theoretical analysis suggests the feasibility of the electromagnetic drag effect in superconductors—the generation of DC supercurrents and second harmonic signals induced by microwave radiation incident on a superconducting surface.

These findings open pathways to the all-optical operation of superconducting devices, including RF SQUID flux qubits.

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Contact : florence.levy-bertrand@neel.cnrs.fr