Electrically programmable polariton symmetry breaking via non-Hermitian dissipation engineering.

The optical response of natural materials is constrained by crystal symmetry, limiting the design of reconfigurable nanophotonic devices. Here we demonstrate the electrically programmable symmetry breaking of phonon polaritons via non-Hermitian dissipation engineering. In a heterostructure composed of α-MoO3 and aligned carbon nanotubes (A-CNTs), we identify the A-CNT layer as an anisotropic dissipative medium. Driven by overdamped carrier dynamics, the nanotubes preclude polariton hybridization, exerting a proximity-induced resistive coupling instead. Thus, the A-CNT layer operates as a tunable momentum-space loss filter that selectively attenuates propagation along specific crystallographic directions. By electrostatically gating the A-CNTs to regulate their Drude loss, we achieve the continuous and reversible tuning of the polariton topology with transitions from symmetric hyperbolas to asymmetric shear wavefronts. Unlike refractive-index engineering that requires strict wavevector matching, this dissipative filtering mechanism allows for topology shaping without coherent hybridization, establishing dissipation as a programmable degree of freedom in topological nanophotonics and non-Hermitian device physics.