On Landau’s Paradigm for the Classification of Phases by Prof Haruki Watanabe
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Join us at this IAS STEM Graduate Colloquium by Prof Haruki Watanabe from the University of Tokyo. This colloquium is in conjunction with the IAS Frontiers Seminars: Quantum Horizons, jointly supported by the Institute of Advanced Studies (IAS) and School of Physical and Mathematical Sciences (SPMS).
About the talk
Traditionally, phases of matter have been classified based on spontaneous symmetry breaking—known as Landau’s paradigm. On the other hand, recent theoretical developments, particularly at absolute zero temperature, have established topological approaches to further distinguish phases that share the same symmetry.
In this colloquium, I will discuss the high-pressure phases of water ice, specifically Ice VII and Ice X, as a pedagogical example of this modern perspective. Despite their distinct physical properties, these phases share the same space group and cannot be distinguished by simple symmetry breaking. By mapping the hydrogen bond network to a spin-1 Ising model on a pyrochlore lattice, I will demonstrate how local constraints (the ice rules) give rise to an emergent gauge field and a Coulomb phase characterized by algebraic dipolar correlations.
About the speaker
Prof Haruki Watanabe is a leading theoretical physicist specialising in condensed matter theory and quantum many-body systems. He earned his BA and MS degrees with honours from the University of Tokyo and completed his PhD at the University of California, Berkeley under Ashvin Vishwanath’s supervision. After a postdoctoral fellowship at MIT as a Pappalardo Fellow, he joined the Department of Applied Physics at the University of Tokyo. Prof Watanabe’s contributions have been recognised with numerous honours, including the 2025 Particle Medal, 2022 New Horizons in Physics Prize, 2017 Condensation Science Prize, and the 2016 Nishinomiya Yukawa Memorial Award. Starting this March, he will join the Hong Kong University of Science and Technology as a Professor of Physics and an IAS Professor.