Uhlmann-Higgs stabilisation of modified causal structures

We present a dynamical gauge theory for purified quantum fields, based on the Uhlmann connection in the extended system ancilla Hilbert space, and demonstrate that nontrivial Uhlmann holonomies induce global modifications of spacetime causal structure. By coupling purified electromagnetic modes to an emergent U(n) gauge field, we derive an effective metric in the geometric optics limit whose curvature contributions tilt and stretch lightcones.