Topological photonics
Light propagating through engineered structures can inherit topological band features.
$$\omega_n(k),\quad C_n=\frac{1}{2\pi}\int\Omega_n\,d^2k$$
What this means
Light propagating through engineered structures can inherit topological band features.
Deep dive: mathematical and physical mechanism
Photonic crystals and coupled-resonator arrays generate band structures with Berry curvature and edge channels. Broken time-reversal symmetry or suitable synthetic gauge fields can create chiral photonic modes. Other designs realize symmetry-protected edge phenomena.
How it appears in quantum phenomena
Waveguides and microwave resonator arrays can guide light along defect-tolerant paths.
Assumptions, caveats and limitations
Photonic topology does not automatically eliminate loss, backreflection from all channels, or fabrication constraints.
Connect the ideas
For context, see the Quantum Phenomena and Applications topic guide and the reading references.