Flat-band many-body localization and ergodicity breaking in the Creutz ladder

Kuno, Yoshihito; Orito, Takahiro; Ichinose, Ikuo

doi:10.1088/1367-2630/ab6352

Cited by 106 publications

(68 citation statements)

References 76 publications

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“…This spontaneous generation of a π flux is in accordance with Lieb's result for bipartite lattices [78], but, in contrast to the square lattice [30,31,33], it does not lead to a semimetallic phase with emergent Dirac fermions [79]. In this case, it is an insulator with complete band flattening caused by destructive Aharonov-Bohm interference at Φ B ¼ π [80], which can result in many-body localization [81]. Because of the remarkable similarities with the Peierls effect, we call this effect the Aharonov-Bohm instability.…”

Section: Aharonov-bohm Instabilitysupporting

confidence: 87%

Robust Topological Order in Fermionic Z2 Gauge Theories: From Aharonov-Bohm Instability to Soliton-Induced Deconfinement

et al. 2020

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Topologically ordered phases of matter, although stable against local perturbations, are usually restricted to relatively small regions in phase diagrams. Thus, their preparation requires a precise fine-tunning of the system's parameters, a very challenging task in most experimental setups. In this work, we investigate a model of spinless fermions interacting with dynamical Z 2 gauge fields on a cross-linked ladder and show evidence of topological order throughout the full parameter space. In particular, we show how a magnetic flux is spontaneously generated through the ladder due to an Aharonov-Bohm instability, giving rise to topological order even in the absence of a plaquette term. Moreover, the latter coexists here with a symmetry-protected topological phase in the matter sector, which displays fractionalized gauge-matter edge states and intertwines with it by a flux-threading phenomenon. Finally, we unveil the robustness of these features through a gauge frustration mechanism, akin to geometric frustration in spin liquids, allowing topological order to survive to arbitrarily large quantum fluctuations. In particular, we show how, at finite chemical potential, topological solitons are created in the gauge field configuration, which bound to fermions and form Z 2 deconfined quasiparticles. The simplicity of the model makes it an ideal candidate for 2D gauge theory phenomena, as well as exotic topological effects, to be investigated using cold-atom quantum simulators.

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Section: Aharonov-bohm Instabilitysupporting

confidence: 87%

Robust Topological Order in Fermionic Z2 Gauge Theories: From Aharonov-Bohm Instability to Soliton-Induced Deconfinement

et al. 2020

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“…It could possess symmetry-protected degenerate zero modes at its boundaries, and therefore belong to one of the earliest examples of a topological insulator [ 66 ]. In later studies, the CL model has been realized in photonic [ 67 , 68 ] and cold atom [ 69 , 70 ] systems, and utilized in the investigations of Aharonov–Bohm cages [ 71 , 72 ], topological pumping [ 73 ], localization [ 74 , 75 ], and many-body topological matter [ 76 , 77 , 78 , 79 , 80 ]. Recently, spin-

extensions of the CL model have also been explored in several studies [ 81 , 82 , 83 ], leading to the discoveries of richer topological features.…”

Section: Model and Symmetrymentioning

confidence: 99%

Non-Hermitian Floquet Phases with Even-Integer Topological Invariants in a Periodically Quenched Two-Leg Ladder

Zhou

2020

Entropy

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Periodically driven non-Hermitian systems could possess exotic nonequilibrium phases with unique topological, dynamical, and transport properties. In this work, we introduce an experimentally realizable two-leg ladder model subjecting to both time-periodic quenches and non-Hermitian effects, which belongs to an extended CII symmetry class. Due to the interplay between drivings and nonreciprocity, rich non-Hermitian Floquet topological phases emerge in the system, with each of them characterized by a pair of even-integer topological invariants ( w 0 , w π ) ∈ 2 Z × 2 Z . Under the open boundary condition, these invariants further predict the number of zero- and π -quasienergy modes localized around the edges of the system. We finally construct a generalized version of the mean chiral displacement, which could be employed as a dynamical probe to the topological invariants of non-Hermitian Floquet phases in the CII symmetry class. Our work thus introduces a new type of non-Hermitian Floquet topological matter, and further reveals the richness of topology and dynamics in driven open systems.

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“…This singleparticle localization effect is a general characteristic of flatband systems [52], wherein the role of the kinetic energy becomes irrelevant and particle motion can only originate from interaction-mediated collective processes. This peculiar feature is responsible for the appearance in such systems of a number of exotic quantum states determined solely by the interactions and the geometry of the lattice [53][54][55][56][57][58][59][60][61][62][63][64][65], including topologically nontrivial phases [66][67][68][69][70].…”

Section: Introductionmentioning

confidence: 99%

Interaction-induced topological properties of two bosons in flat-band systems

Pelegrí

Marques

Ahufinger

et al. 2020

Phys. Rev. Research

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In flat-band systems, destructive interference leads to the localization of noninteracting particles and forbids their motion through the lattice. However, in the presence of interactions the overlap between neighboring single-particle localized eigenstates may enable the propagation of bound pairs of particles. In this work, we show how these interaction-induced hoppings can be tuned to obtain a variety of two-body topological states. In particular, we consider two interacting bosons loaded into the orbital angular momentum l = 1 states of a diamond-chain lattice, wherein an effective π flux may yield a completely flat single-particle energy landscape. In the weakly interacting limit, we derive effective single-particle models for the two-boson quasiparticles which provide an intuitive picture of how the topological states arise. By means of exact diagonalization calculations, we benchmark these states and we show that they are also present for strong interactions and away from the strict flat-band limit. Furthermore, we identify a set of doubly localized two-boson flat-band states that give rise to a special instance of Aharonov-Bohm cages for arbitrary interactions.

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Flat-band many-body localization and ergodicity breaking in the Creutz ladder

Cited by 106 publications

References 76 publications

Robust Topological Order in Fermionic Z2 Gauge Theories: From Aharonov-Bohm Instability to Soliton-Induced Deconfinement

Robust Topological Order in Fermionic Z2 Gauge Theories: From Aharonov-Bohm Instability to Soliton-Induced Deconfinement

Non-Hermitian Floquet Phases with Even-Integer Topological Invariants in a Periodically Quenched Two-Leg Ladder

Interaction-induced topological properties of two bosons in flat-band systems

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