Fig. 2: Dynamical inversion symmetry breaking and odd-parity Bardasis-Schrieffer (BS) modes.
From: Light-induced switching between singlet and triplet superconducting states
a, b Demonstration of a linear-in-∣A∣ and linear-in-λ (spin-orbit parameter) coupling between an equilibrium order parameter Δs and a px-wave order parameter \({\Delta }_{{p}_{x}}\). A two-color x-polarized pulse that breaks dynamical inversion symmetry is applied with various small magnitudes ∣A∣, and example time-plots of the resulting fluctuations in \(| {\Delta }_{{p}_{x}}(t)|\) are plotted in (b). The maxima of these fluctuations are plotted versus ∣A∣ in (a), for five different magnitudes of the spin-orbit coupling strength λ in units of hopping. c Time dynamics resulting from a two-color pulse that breaks dynamical inversion symmetry (with a 2: 1 frequency ratio). d Time dynamics resulting from a two-color pulse that preserves dynamical inversion symmetry (with a 3: 1 frequency ratio). Both (c) and (d) start from purely even superconducting order (indicated by blue curves), and the onset of odd orders (indicated by red and pink curves) is suppressed when dynamical inversion symmetry is unbroken (see legend in bottom right). e Short-time deviations in the s-wave and px-wave order parameters for weak driving with x-polarized light as a function of frequency Ω, revealing a BS mode for the px-wave order parameter that is sub-gap (indicated by the unshaded region).
