Higgs spectroscopy of nonequilibrium superconductors

In addition to the superconducting gap symmetry, when a superconductor is excited, the collective excitations of the condensate can exhibit an additional symmetry, which also mirrors the underlying lattice symmetry. Therefore the aggregate of these symmetries can result in one or more amplitude-Higgs modes depending on the geometry of the excitation. We study s-wave and d-wave superconducting symmetries on a lattice with D_4h space group symmetry, which is the lattice symmetry of cuprate high-T_c superconductors. We report analytic results on the specific geometries of a quench needed for producing oscillation modes along different geometries. Remarkably, we find that, in addition to the well-studied 2△_∞ mode, a second low energy mode can also be excited, depending on the symmetry of the quench. Lastly, we also predict results for time-resolved Higgs spectroscopy with a realistic experimental pulse.