Topology-guided vortices in a polariton condensate

TL;DR

This paper demonstrates how cavity geometry in a polariton condensate can intrinsically control spin textures and topological vortices, enabling robust topological excitations even in disordered materials.

Contribution

It introduces a novel method of generating and controlling spin vortices in polariton condensates via topology-guided cavity design without external gauge fields.

Findings

Polariton condensates exhibit spin vortices pinned to polarization strings.

Vortex displacement can be controlled by excitation density.

Cavity geometry acts as an intrinsic source of spin textures.

Abstract

A major challenge in polariton fluids is achieving deterministic control over the spin texture of the macroscopic condensate wavefunction, which dictates the nucleation and dynamics of topological excitations, such as vortices, solitons, and strings. Existing approaches typically rely on external gauge fields to indirectly access the polariton pseudospin, resulting in configurations that are weakly constrained by the cavity modes and therefore highly sensitive to disorder and fluctuations. Here, we report the generation of spin polaritons constrained to the topology of a bound state in the continuum (BIC) metasurface with broken inversion symmetry carved into a polycrystalline halide-perovskite film. Geometry-induced polariton condensation under spin-momentum locking gives rise to a pair of half-vortices of opposite spin, intrinsically pinned to polarization strings, emerging as topological extensions of the vortex cores. Consequently, varying the excitation density drives a controlled displacement of the half-vortices along the trajectories imposed by the strings, hindering their mutual annihilation across an interposed topological domain wall. This approach establishes cavity geometry as an intrinsic source of spin textures to guide vortex displacement in driven quantum fluids, opening a route toward the generation of robust topological excitations within structurally disordered materials.