SMRI Seminar `Quantum geometry of 3-dimensional lattices’ Vladimir Bazhanov (Australian National University) October 26, 2021 2:00pm - 3:00pm via Zoom. REGISTER HERE: https://uni-sydney.zoom.us/meeting/register/tZMvceuqrDMsGdCAEu6zpUf-6XeU1nuSR_SJ Abstract: In this lecture I will explain a relationship between incidence theorems in elementary geometry and the theory of integrable systems, both classical and quantum. We will study geometric consistency relations between angles of 3-dimensional (3D) circular quadrilateral lattices -- lattices whose faces are planar quadrilaterals inscribable into a circle. We show that these relations generate canonical transformations of a remarkable "ultra-local" Poisson bracket algebra defined on discrete 2D surfaces consisting of circular quadrilaterals. Quantization of this structure allowed us to obtain new solutions of the tetrahedron equation (the 3D analog of the Yang-Baxter equation) as well as reproduce all those that were previously known. These solutions generate an infinite number of non-trivial solutions of the Yang-Baxter equation and also define integrable 3D models of statistical mechanics and quantum field theory. The latter can be thought of as describing quantum fluctuations of lattice geometry.