60 citations · 401 across the 19 of their papers we have counts for
20 papers
Remarks on invertible phases with non-onsite symmetry
Ryohei Kobayashi, Kansei Inamura, Ken Shiozaki
We study invertible phases protected by non-onsite symmetries carrying nontrivial lattice anomaly indices. While lattice anomalies are usually viewed as obstructions to symmetric s…
Complete crystalline topological invariants from partial rotations in (2+1)D invertible fermionic states and Hofstadter's butterfly
Yuxuan Zhang, Naren Manjunath, Ryohei Kobayashi +1
The theory of topological phases of matter predicts invariants protected only by crystalline symmetry, yet it has been unclear how to extract these from microscopic calculations in…
Extracting higher central charge from a single wave function
Ryohei Kobayashi, Taige Wang, Tomohiro Soejima +2
A (2+1)D topologically ordered phase may or may not have a gappable edge, even if its chiral central charge is vanishing. Recently, it is discovered that a quantity regarded…
Fermionic defects of topological phases and logical gates
Ryohei Kobayashi
We discuss the codimension-1 defects of (2+1)D bosonic topological phases, where the defects can support fermionic degrees of freedom. We refer to such defects as fermionic defects…
Higher-group symmetry in finite gauge theory and stabilizer codes
Maissam Barkeshli, Yu-An Chen, Po-Shen Hsin +1
A large class of gapped phases of matter can be described by topological finite group gauge theories. In this paper we show how such gauge theories possess a higher-group global sy…
Codimension-2 defects and higher symmetries in (3+1)D topological phases
Maissam Barkeshli, Yu-An Chen, Sheng-Jie Huang +3
(3+1)D topological phases of matter can host a broad class of non-trivial topological defects of codimension-1, 2, and 3, of which the well-known point charges and flux loops are s…
Symmetry-preserving boundary of (2+1)D fractional quantum Hall states
Ryohei Kobayashi
We investigate symmetry-preserving gapped boundary of (2+1)D topological phases with global symmetry, which can be either bosonic or fermionic. We develop a general algebraic descr…
(3+1)D path integral state sums on curved U(1) bundles and U(1) anomalies of (2+1)D topological phases
Ryohei Kobayashi, Maissam Barkeshli
Given the algebraic data characterizing any (2+1)D bosonic or fermionic topological order with a global symmetry group , we construct a (3+1)D topologi…
Lattice construction of exotic invertible topological phases
Ryohei Kobayashi
In this paper, we provide state sum path integral definitions of exotic invertible topological phases proposed in the recent paper by Hsin, Ji, and Jian. The exotic phase has time…
Anomalies in (2+1)D fermionic topological phases and (3+1)D path integral state sums for fermionic SPTs
Sri Tata, Ryohei Kobayashi, Daniel Bulmash +1
Given a (2+1)D fermionic topological order and a symmetry fractionalization class for a global symmetry group , we show how to construct a (3+1)D topologically invariant path in…
Topological terms of (2+1)d flag-manifold sigma models
Ryohei Kobayashi, Yasunori Lee, Ken Shiozaki +1
We examine topological terms of d sigma models and their consequences in the light of classifications of invertible quantum field theories utilizing bordism groups. In parti…
Anomaly constraint on chiral central charge of (2+1)d topological order
Ryohei Kobayashi
In this short paper, we argue that the chiral central charge of a (2+1)d topological ordered state is sometimes strongly constrained by 't Hooft anomaly of anti-unitary globa…
Commuting projector models for (3+1)d topological superconductors via string net of (1+1)d topological superconductors
Ryohei Kobayashi
We discuss a way to construct a commuting projector Hamiltonian model for a (3+1)d topological superconductor in class DIII. The wave function is given by a sort of string net of t…
Non-local Order Parameters and Quantum Entanglement for Fermionic Topological Field Theories
Kansei Inamura, Ryohei Kobayashi, Shinsei Ryu
We study quantized non-local order parameters, constructed by using partial time-reversal and partial reflection, for fermionic topological phases of matter in one spatial dimensio…
Pin TQFT and Grassmann integral
Ryohei Kobayashi
We discuss a recipe to produce a lattice construction of fermionic phases of matter on unoriented manifolds. This is performed by extending the construction of spin TQFT via the Gr…
On gapped boundaries for SPT phases beyond group cohomology
Ryohei Kobayashi, Kantaro Ohmori, Yuji Tachikawa
We discuss a strategy to construct gapped boundaries for a large class of symmetry-protected topological phases (SPT phases) beyond group cohomology. This is done by a generalizati…
Anomaly indicator of rotation symmetry in (3+1)D topological order
Ryohei Kobayashi, Ken Shiozaki
We examine (3+1)D topological ordered phases with rotation symmetry. We show that some rotation symmetric (3+1)D topological orders are anomalous, in the sense that they cann…
Lieb-Schultz-Mattis type theorem with higher-form symmetry and the quantum dimer models
Ryohei Kobayashi, Ken Shiozaki, Yuta Kikuchi +1
The Lieb-Schultz-Mattis theorem dictates that a trivial symmetric insulator in lattice models is prohibited if lattice translation symmetry and charge conservation are both…
Scaling of polarization amplitude in quantum many-body systems in one dimension
Ryohei Kobayashi, Yuya O. Nakagawa, Yoshiki Fukusumi +1
Resta proposed a definition of the electric polarization in one-dimensional systems in terms of the ground-state expectation value of the large gauge transformation operator. Vanis…
Exact zero modes in twisted Kitaev chains
Kohei Kawabata, Ryohei Kobayashi, Ning Wu +1
We study the Kitaev chain under generalized twisted boundary conditions, for which both the amplitudes and the phases of the boundary couplings can be tuned at will. We explicitly…