Quantum quenches of an SO(5) pseudospin reveal Higgs bosons

A controlled dynamical probe measurement of complex order parameter fluctuations of a system may reveal its massive collective excitations. Here, we design dynamical quench protocols to excite independently all ten midgap Higgs bosons in the isotropic Balian-Werthamer state of a spinful <em>p</em>-wave superfluid or superconductor. The analysis is based on microscopic equations of motion of an SO(5) pseudospin, an extension of the usual Bloch equation to a five-dimensional space. Key to these protocols is the realization of quenches that break the rotational symmetry of the kinetic energy and exploit the irreducible representation of the angular momentum <em>J</em> = 2. For perturbative quenches, we find (<em>nondecaying</em>) periodic oscillations in time of these Higgs modes. Finally, we present experimental protocols for superconductors (superfluids), with the intention of unveiling the nature of their order parameters.