Insights from the crosscap state towards non-orientable TQFTs

11 AM, 7 Apr 2026

Ippo Orii surveys topological field theories and discusses the implications of recent progress in extending them to non-orientable manifolds.

Topological quantum field theories (TQFTs) in 2+1 dimensions describe gapped phases supporting anyons, with a successful formulation in terms of modular tensor categories. However, this framework relies on spacetime orientability. Ippo Orii surveys current efforts to extend TQFTs to non-orientable manifolds—which are closely tied to time-reversal symmetry— and highlights key physical insights guiding their construction.

Ippo Orii is a graduate student in theoretical physics at the Kavli Institute for the Physics and Mathematics of the Universe, University of Tokyo. His research focuses on topological quantum field theory, with interests in symmetry, anomalies and non-orientable manifolds.

 Insights from the crosscap state towards non-orientable TQFTs
 Insights from the crosscap state towards non-orientable TQFTs
 Insights from the crosscap state towards non-orientable TQFTs
 Insights from the crosscap state towards non-orientable TQFTs
 Insights from the crosscap state towards non-orientable TQFTs
 Insights from the crosscap state towards non-orientable TQFTs
 Insights from the crosscap state towards non-orientable TQFTs
 Insights from the crosscap state towards non-orientable TQFTs
 Insights from the crosscap state towards non-orientable TQFTs
 Insights from the crosscap state towards non-orientable TQFTs
 Insights from the crosscap state towards non-orientable TQFTs
 Insights from the crosscap state towards non-orientable TQFTs
 Insights from the crosscap state towards non-orientable TQFTs
 Insights from the crosscap state towards non-orientable TQFTs
 Insights from the crosscap state towards non-orientable TQFTs
 Insights from the crosscap state towards non-orientable TQFTs