部分次元粒子:格子模型、場の理論、背景の数学的構造
Taiichi Nakanishi
Topologically ordered phases and their continuum descriptions provide a rich arena in which quantum many-body systems, algebraic topology, and quantum field theory meet.Recently, foliated fracton phases with subdimensional particles, which are excitations constrained to move only along lower-dimensional submanifolds, have emerged as a new class of quantum matter with potential applications to robust quantum information storage.These phases are naturally tied to foliation structures of the spatial manifold and exhibit unusual ground state degeneracies and subsystem conservation laws that go beyond conventional topological order.In this thesis we investigate subdimensional particles from three complementary viewpoints: lattice stabilizer codes, mathematical structures on manifolds, and continuum gauge theories.As a warm-up, we revisit the toric code and show how its stabilizer structure, logical operators, and ground state degeneracy are encoded in cellular (co)homology.This "triangle of ideas" relating lattice models, BF-type topological quantum field theories, and topological invariants serves as a guiding paradigm.We then extend this perspective to foliated fracton phases, focusing on the plaquette Ising model and the X-cube model as paradigmatic examples.We clarify how their subextensive ground state degeneracies and rigid line and membrane operators are organized by foliation-sensitive (co)homological data of the underlying manifold.Motivated by these observations, we construct a Godbillon-Vey U(1) BF-like gauge theory coupled to a codimension-one foliation.By promoting the redundancies of the foliation data to gauge symmetries, the resulting continuum theory depends only on the foliation class and naturally realizes Wilson and higher-form operators whose mobility is restricted to the leaves.In (2+1)-and (3+1)-dimensions we show that this theory reproduces, respectively, the ground state degeneracy and operator algebra of the plaquette Ising and X-cube models, providing a foliated analogue of the BF-toric code correspondence.Finally, we introduce matter field theories coupled to the foliation background and to the BF-like gauge fields.For complex scalars, fermions, and compact scalars we construct conserved currents that obey leafwise conservation laws enforcing subdimensional kinematics.We close by outlining extensions to higher-codimension foliations, more general G-structures, and symmetry topological field theories, and by emphasizing a generalized triangle relating microscopic models, geometric invariants, and continuum field theories for subdimensional particle systems.
•Mar 23, 2026•0 citations