As a graduate student Qihou Liu studied 3-dimensional topology and knot theory. The volume conjecture, which relates Chern–Simons gauge theory to hyperbolic volume, is the central theme of his thesis, in which he settled two special cases. The first of the two preprints below was later quoted and extended by H. Murakami and A. T. Tran in Kashaev invariants of twice-iterated torus knots, Topology and its Applications 290 (2021).
His interests since then have centred on the relation between topology and quantum field theory. Algebraic constraints often suggest the shape of a quantum theory in the way that symmetry principles do in quantum physics, sparing the hard analysis. While visiting the Institute of Advanced Study at Tsinghua in 2010 he organised a seminar on vertex operator algebras and tensor categories with Liang Kong, Hao Zheng and Yinghua Ai.
From 2014 to 2018 he visited Dezhuan Han at Chongqing University each summer, working on topological effects in optics and on topological insulators, and contributing tensor decomposition calculations to their joint work.