From the theory of gapless boundaries of 2+1D topological orders to topological Wick rotation

Liang Kong reviews a unified mathematical treatment of gapped and gapless boundaries in topological orders in two spatial dimensions. It leads to topological Wick rotation, proposed as a broader organising principle for suitable quantum field theories. The talk examines generalisations and applications, including how familiar topological holography and sandwich constructions emerge as special cases.