Benedetta Flebus

Frustration, complex pairing, and equilibrium loop currents are recurring ingredients in descriptions of unconventional quantum matter. In this talk, I will show how these structures emerge in the quantum vacuum of a centrosymmetric altermagnet whose static magnetic order remains perfectly collinear. A symmetry-allowed, locally staggered Dzyaloshinskii–Moriya interaction generates complex two-magnon squeezing, imprinting a vortex–antivortex pair on the ground-state spin correlations. I will discuss how the associated gauge-invariant fluxes give rise to an antiferrochiral pattern of equilibrium spin currents, circulating in opposite directions around neighboring plaquettes with no net transport. The frustration thus resides entirely in the quantum correlations and remains invisible in the static spin configuration. I will then show how analogous angular-momentum circulation emerges in purely phononic systems that preserve time-reversal and inversion symmetry, highlighting the distinct roles of directional elasticity and angular-momentum nonconservation. Together, these findings reveal that seemingly conventional ordered solids can harbor a quantum vacuum with its own geometry, frustration, and patterns of circulation.