The University of Tokyo · 물리·천문학
Linhao Li 교수의 연구실은 대칭 보호 양자 상태(SPT)와 그 확장인 비가역 상태를 중심으로, 특히 비가역적 대칭 변환과 비단위(unitary) 대칭 변환을 통한 양자 상 전이를 연구합니다. 고립계와 개방계에서의 대칭 보호 상의 위상 전이, 특히 케네디-타사키 변환의 비단위성 및 비가역적 편재성에 기반한 새로운 양자 상의 구조를 분석하며, 비가역적 대칭 변환과 장점의 결합을 통해 비가역적 양자 상의 기초를 탐색합니다. 또한 비가역적 대칭 변환을 활용한 비가역적 양자 상의 구조적 특성과 그 안정성, 경계 상태의 위상적 성질을 정량적으로 분석합니다.
표시된 성과는 수집된 데이터 기준으로 산출되며, 일부 차이가 있을 수 있습니다.
In 1992, Kennedy and Tasaki constructed a nonlocal unitary transformation that maps between a ${\mathbb{Z}}_{2}\ifmmode\times\else\texttimes\fi{}{\mathbb{Z}}_{2}$ spontaneously symmetry breaking phase and the Haldane gap phase, which is a prototypical symmetry-protected topological (SPT) phase in modern framework, on an open spin chain. In this work, we propose a way to define it on a closed chain by sacrificing unitarity. The operator realizing such a nonunitary transformation satisfies noninve
Symmetry protected topological (SPT) phases are one of the simplest, yet nontrivial, gapped systems that go beyond the Landau paradigm. In this work, we study an extension of the notion of SPT for gapless systems, namely, gapless symmetry protected topological states. We construct several simple gapless-SPT models using the decorated defect construction, which allow analytical understanding of non-trivial topological features including the symmetry charge under twisted boundary conditions, and b
The Kennedy-Tasaki (KT) transformation was used to construct the gapped symmetry protected topological (SPT) phase from the symmetry breaking phase with open boundary condition, and was generalized in our proceeding work [Phys. Rev. B 108, 214429 (2023)] on a ring by sacrificing the unitarity, and should be understood as a non-invertible duality transformation. In this work, we further apply the KT transformation to systematically construct gapless symmetry protected topological phases. This con
Symmetry protected topological (SPT) phases are one of the simplest, yet nontrivial, gapped systems that go beyond the Landau paradigm. In this work, we study an extension of the notion of SPT for gapless systems, namely, gapless symmetry protected topological states. We construct several simple gapless-SPT models using the decorated defect construction, which allow analytical understanding of non-trivial topological features including the symmetry charge under twisted boundary conditions, and b
We study a relationship between conformally invariant boundary conditions and anomalies of conformal field theories (CFTs) in $1+1$ dimensions. For a given CFT with a global symmetry, we consider symmetric ``gapping potentials'', which are relevant perturbations to the CFT. If a gapping potential is introduced only in a subregion of the system, it provides a certain boundary condition to the CFT. From this equivalence, if there exists a Cardy boundary state, which is invariant under a symmetry,
