Abstract The ability to rapidly control and manipulate superconducting states is one of the great challenges of modern condensed matter physics. Circularly polarized radiation interacting with a superconducting condensate acts as an effective magnetic field that can generate supercurrents and DC magnetic moments through the inverse Faraday effect (IFE). Using the time‐dependent Ginzburg–Landau (TDGL) equation formalism, the current‐carrying states of a small superconducting ring illuminated by such radiation is calculated. Numerical simulations demonstrate the possibility to on‐demand switch between current‐carrying states in the superconductor by controlling the helicity of the electromagnetic field polarization. This result opens the way to all‐optical operation of superconducting devices.
In this paper, we address the impact of the electric field on superconductors which are insulators in the normal state, semiconductors at low carrier concentration and ultracold gas of fermions in the strongly interacting regime. The electric field penetrates these systems and effects on the Cooper pairs. We show that if there are Cooper pairs above the superconductor critical temperature, the electric field forces the Cooper pairs to Bose condensate and the onset of the superconductivity, thereby increasing the critical temperature. To study this phenomenon, we numerically solve the Maxwell equations for [Formula: see text]-wave superconductors obtained from the time-dependent Ginzburg–Landau theory. Our investigation designs an experimental way for verification of the pairing of Fermions preceding superconductivity and superfluidity.
Abstract Using light irradiation to manipulate quantum materials has opened up avenues for transiently inducing superconductivity in some systems. Despite experimental confirmation across various compounds, the mechanism behind the dynamic formation of Cooper pairs remains highly debated, in part due to the strong electronic correlations at play, which pose challenges for theoretical investigations relying on perturbative or phenomenological approaches. Here, we investigate the dynamical onset of superconductivity in the strongly correlated, yet exactly solvable Yukawa-Sachdev-Ye-Kitaev model. Analyzing dynamical protocols motivated by theoretical mechanisms proposed for light-induced superconductivity, that is light-induced cooling and the dressing of Hamiltonian parameters, we investigate the exact relaxation resulting out of undercooling and interaction quenches. While, in contrast to BCS theory, it is not possible for superconductivity to emerge following interaction quenches across the superconducting phase transition, we find that the dynamical relaxation of undercooled states universally leads to superconductivity. Despite the strong correlations, the emerging order parameter dynamics are well captured by a coarse grained Ginzburg-Landau theory. Our study provides an integral stepping stone towards exploring light-induced superconductivity in strongly correlated systems in a theoretically controlled way.
The inverse Faraday effect (IFE), where a static magnetization is induced by circularly polarized light, offers a promising route to ultrafast control of spin states. Here we study the IFE in Mott insulators using the Floquet theory. We find two distinct IFE behavior governed by the inversion symmetry. In the Mott insulators with inversion symmetry, we find that the effective magnetic field induced by the IFE couples ferromagnetically to the neighboring spins. While for the Mott insulators without inversion symmetry, the effective magnetic field due to IFE couples antiferromagnetically to the neighboring spins. We apply the theory to the spin-orbit coupled single- and multiorbital Hubbard model that is relevant for the Kitaev quantum spin liquid material and demonstrate that the magnetic interactions can be tuned by light.
Within a gauge-invariant microscopic kinetic theory, we study the electromagnetic response in the superconducting states. Both superfluid and normal-fluid dynamics are involved. We predict that the normal fluid is present only when the excited superconducting velocity
vs is larger than a threshold ${v}_{L}=|\mathrm{\ensuremath{\Delta}}|/{k}_{F}$. Interestingly, with the normal fluid, we find that there exists friction between the normal-fluid and superfluid currents. Due to this friction, part of the superfluid becomes viscous. Therefore a three-fluid model, normal fluid and nonviscous and viscous superfluids, is proposed. For the stationary magnetic response, at
vs<vL with only the nonviscous superfluid, the Meissner supercurrent is excited and the gap equation can be reduced to the Ginzburg-Landau equation. At ${v}_{s}\ensuremath{\ge}{v}_{L}$, with the normal fluid and nonviscous and viscous superfluids, in addition to the directly excited Meissner supercurrent in the superfluid, a normal-fluid current is also induced through the friction drag with the viscous superfluid current. Due to the normal-fluid and viscous-superfluid currents, the penetration depth is influenced by the scattering effect. In addition, a modified Ginzburg-Landau equation is proposed. We predict an exotic phase in which both the resistivity and superconducting gap are finite. As for the optical response, the excited
vs oscillates with time. When
vs<vL, only the nonviscous superfluid is present, whereas at ${v}_{s}\ensuremath{\ge}{v}_{L}$, normal fluid and nonviscous and viscous superfluids are present. We show that the excited normal-fluid current exhibits the Drude-model behavior, while the superfluid current consists of the Meissner supercurrent and Bogoliubov quasiparticle current. Due to the friction between the superfluid and normal-fluid currents, the optical conductivity is captured by the three-fluid model. Finally, we also study the optical excitation of the Higgs mode. By comparing the contributions from the drive and Anderson-pseudospin pump effects, we find that the drive effect is dominant at finite temperature whereas at zero temperature, both effects contribute.
The Meissner effect is a hallmark of superconductivity arising from the interplay between charged superfluids and electromagnetic fields. However, superfluidity can also occur in systems of charge-neutral particles with magnetic or electric dipole moments, such as Bose-Einstein condensates of magnons or excitons. Despite this interest, the electromagnetic response of dipole superfluids, including potential analogues or contrasts to the Meissner effect, remains poorly understood. Here we develop a Ginzburg-Landau theory to describe dipole superfluids subjected to a pseudo-magnetic field, which is induced by a spatially modulating electromagnetic field. In magnetic dipole superfluids, the response differs strikingly from the conventional Meissner effect: the external field is enhanced by a positive feedback, forming a vortex lattice separated by singular domain walls with diverging electric charges. In contrast, electric dipole superfluids exhibit screening akin to superconductors, where the pseudo-magnetic field is suppressed except near vortices. The electromagnetic response of dipole superfluids, including potential analogues to the Meissner effect, remains poorly understood. This paper develops a phenomenological theory and shows that magnetic-dipole superfluids form vortex lattices separated by singular domain walls with concentrated electric charge, while electric-dipole superfluids exhibit vortex lattices resembling those in conventional superconductors.