Non-invertible symmetries in quantum many-body systems generally give rise to sequential unitary circuits that move symmetry defects. In this paper, we investigate invariants defined by sequences of such circuits, which move non-invertible defects and generate a Berry phase evaluated on quantum states with defects. We show that this Berry phase generally defines an invariant under local deformations, provided that the sequential circuits preserve the locality of those deformations. This invariant also rules out a short-range-entangled state that preserves the non-invertible symmetry, thereby signaling the 't Hooft anomaly of a non-invertible symmetry purely in terms of unitary operators acting on a state. We then apply this framework to loop excitations in three spatial dimensions and identify a new loop excitation in the (3+1)D $\mathbb{D}_4$ topological order, which we dub a non-Abelian fermionic loop. Using the invariant of sequential circuits, we characterize the statistics of non-Abelian fermionic loops. In addition, we find a new (3+1)D mixed topological order with a single non-Abelian fermionic loop, whose long-range entanglement is protected by an invariant of sequential circuits.
Non-invertible symmetries in quantum many-body systems generally give rise to sequential unitary circuits that move symmetry defects. In this paper, we investigate invariants defined by sequences of such circuits, which move non-invertible defects and generate a Berry phase evaluated on quantum states with defects. We show that this Berry phase generally defines an invariant under local deformations, provided that the sequential circuits preserve the locality of those deformations. This invariant also rules out a short-range-entangled state that preserves the non-invertible symmetry, thereby signaling the 't Hooft anomaly of a non-invertible symmetry purely in terms of unitary operators acting on a state. We then apply this framework to loop excitations in three spatial dimensions and identify a new loop excitation in the (3+1)D D4 topological order, which we dub a non-Abelian fermionic loop. Using the invariant of sequential circuits, we characterize the statistics of non-Abelian fermionic loops. In addition, we find a new (3+1)D mixed topological order with a single non-Abelian fermionic loop, whose long-range entanglement is protected by an invariant of sequential circuits.
The statistics of particles and extended excitations, such as loops and membranes, are fundamental to modern condensed matter physics, high-energy physics, and quantum information science, yet a comprehensive lattice-level framework for computing them remains elusive. In this work, we develop a universal microscopic method to determine the generalized statistics of Abelian excitations on lattices of arbitrary dimension and demonstrate it by deriving the statistics of particles, loops, and membranes in up to three spatial dimensions. Our approach constructs a sequence of local unitary operators whose many-body Berry phase encodes the desired statistical invariant. The required sequence is generated automatically from the Smith normal form of locality constraints and therefore needs no extra physical input. We prove that the resulting invariants are quantized, provide an algorithm that computes them efficiently, and show how they unify familiar braiding and fusion data of particles while also uncovering new self- and mutual statistics of loop and membrane excitations. We further demonstrate that each statistical invariant corresponds to an ’t Hooft anomaly of a generalized symmetry; we show that a nontrivial invariant both (i) obstructs gauging that symmetry and (ii) forbids any short-range-entangled (symmetry-preserving) ground state. This establishes a precise connection between microscopic lattice anomalies and many-body dynamics, providing a generalization of the Lieb-Schultz-Mattis theorem that constrains a wide class of quantum lattice systems.
The Landau paradigm—classifying phases by local order parameters and transitions by spontaneous symmetry breaking—has long been understood to be incomplete. Deconfined quantum critical points (DQCPs), topological orders, and symmetry-protected phases resist Landau characterization. A candidate structural pattern now emerging across the cond-mat.str-el corpus is that the failure of the Landau paradigm is not merely an exception but a systematic consequence of three interlocking mechanisms: (1) the presence of non-invertible symmetries whose breaking generates order parameters obeying generalized algebraic structures rather than group representations; (2) the role of anomaly type—specifically the position of the Lieb-Schultz-Mattis (LSM) anomaly class in the Lyndon-Hochschild-Serre spectral sequence—in determining whether a critical point is dual to ordinary symmetry breaking or to non-invertible symmetry breaking; and (3) excitation-density control as the decisive factor separating phases that merely enter the topological regime from those that develop genuine topological order. This synthesis draws on six papers from cond-mat.str-el and one from cond-mat.mes-hall (as a mechanistic comparator), all posted within the last 30 days. The thesis is presented as a *heuristic structural reading*, not a derivation from a shared formalism: the cited papers use distinct mathematical frameworks (fusion categories, spectral sequences, sequential circuits, tensor networks, quadratic fermion mappings), and we argue that these frameworks share a common organizational principle—the algebra of defects and condensable objects—rather than a common Lagrangian. The primary falsification path is explicit: if a direct DQCP transition between twin phases (as defined by [corpus:arxiv:2605.31601v1]) can be shown to be continuously connected to a hidden symmetry-breaking transition upon deformation of the Hamiltonian, the structural independence of beyond-Landau transitions claimed here would be overturned. Numerical DMRG or tensor-network studies on the specific models of [corpus:arxiv:2606.06343v1] and [corpus:arxiv:2605.27672v1] with explicitly broken categorical symmetry would constitute such a test. --- Authorship: Saluca Agentic AI Research Team (Saluca LLC). AI-drafted from arXiv preprint corpus on the date in the filename. Cited arXiv preprints: 2605.27166v1, 2605.27193v1, 2605.27672v1, 2605.31601v1, 2605.31602v1, 2606.05856v1, 2606.06343v1, 2606.11303v1, 2606.11527v1
A structural pattern is emerging across several recent preprints in strongly correlated and topological quantum matter: the machinery of non-invertible symmetry — symmetries whose defects do not compose invertibly — provides a coherent organizational framework for phases and transitions that resist conventional Landau-Ginzburg-Wilson description. This synthesis draws on seven papers from the cond-mat.str-el and cond-mat.mes-hall categories, spanning lattice spin chains, topological field theory, sequential circuit invariants, and mesoscopic collider experiments. The thesis, offered as a heuristic reading rather than a derivation from a shared formalism, is as follows: non-invertible symmetry simultaneously (i) enriches the classification of topological orders beyond the invertible-symmetry-enriched (SET) framework, (ii) controls the universal categorical structure of deconfined quantum critical points (DQCPs) via LSM anomalies in spectral sequences, (iii) generates order parameters organized as Lagrangian algebras in Drinfeld centers, (iv) enables twin phases — inequivalent phases with isomorphic ground-state spaces that undergo transitions without any hidden symmetry breaking, and (v) produces measurable loop-excitation statistics in (3+1)D that are detectable through sequential-circuit invariants. A concrete falsification path runs through numerics: DMRG computation of the central charge and entanglement spectrum at the Rep(H₈)-type DQCP candidate in the spin-1/2 D₈ chain should yield c ≈ 1 with specific operator content; deviation from this prediction, or discovery of a first-order signal, would overturn the categorical Landau description reported for that transition. The synthesis is limited by abstract-only reading and the heuristic nature of the cross-paper unification. --- Authorship: Saluca Agentic AI Research Team (Saluca LLC). AI-drafted from arXiv preprint corpus on the date in the filename. Cited arXiv preprints: 2605.27193, 2605.27672, 2605.28688, 2605.28794, 2605.30421, 2605.31601, 2605.31602, 2606.04958, 2606.05856, 2606.06343, 2606.11147, 2606.11303, 2606.11527
Anomalies of global symmetries are important tools for understanding the dynamics of quantum systems. We investigate anomalies of non-invertible symmetries in 3+1d using 4+1d bulk topological quantum field theories given by Abelian two-form gauge theories, with a 0-form permutation symmetry. Gauging the 0-form symmetry gives the 4+1d “inflow” symmetry topological field theory for the non-invertible symmetry. We find a two levels of anomalies: (1) the bulk may fail to have an appropriate set of loop excitations which can condense to trivialize the boundary dynamics, and (2) the “Frobenius-Schur indicator” of the non-invertible symmetry (generalizing the Frobenius-Schur indicator of 1+1d fusion categories) may be incompatible with trivial boundary dynamics. As a consequence we derive conditions for non-invertible symmetries in 3+1d to be compatible with symmetric gapped phases, and invertible gapped phases. Along the way, we see that the defects characterizing \mathbb{Z}_{4} ℤ 4 ordinary symmetry host worldvolume theories with time-reversal symmetry \mathsf{T} 𝖳 obeying the algebra \mathsf{T}^{2}=C 𝖳 2 = C or \mathsf{T}^{2}=(-1)^{F}C, 𝖳 2 = ( − 1 ) F C , with C C a unitary charge conjugation symmetry. We classify the anomalies of this symmetry algebra in 2+1d and further use these ideas to construct 2+1d topological orders with non-invertible time-reversal symmetry that permutes anyons. As a concrete realization of our general discussion, we construct new lattice Hamiltonian models in 3+1d with non-invertible symmetry, and constrain their dynamics.
Braiding phenomena, from the charge-flux Aharonov-Bohm effect to anyonic statistics in fractional quantum Hall systems, are paradigmatic manifestations of topology in quantum physics. Ordinary mutual braiding between p- and q-dimensional excitations occurs in d=p+q+2 spatial dimensions. In this work, we introduce a universal construction of mutual statistics in the adjacent dimension d=p+q+1, applicable to excitations obeying ZN fusion for arbitrary N and all excitation dimensions p and q. The corresponding invariant is the Berry phase accumulated in a simple 4N-step microscopic unitary process built from local excitation operators on lattices. This process measures the linking of one excitation with the N-fold fusion junction of the other, encompassing particle-particle statistics in one dimension, particle-loop statistics in two dimensions, and loop-loop or particle-membrane statistics in three dimensions. We establish the quantization and bilinearity of the invariant and show that its field-theory response is governed by the Bockstein homomorphism, motivating the name Bockstein braiding statistics. Interpreting the excitation operators as open symmetry operators turns the same invariant into a direct microscopic diagnostic of mixed anomalies between symmetries. We demonstrate this diagnostic in a (1+1)D spin chain, where the nontrivial Bockstein braiding phase proves the mixed anomaly between the spin-flip symmetry ∏X and the nearest-neighbor controlled-Z symmetry ∏CZ. We construct explicit (2+1)D and (3+1)D lattice analogs, yielding new anomalous symmetry pairs, and apply the framework to strongly coupled (3+1)D continuum gauge theories. Nontrivial Bockstein braiding rules out a fully symmetric gapped phase, obstructs simultaneous condensation of the two excitations, and implies fractionalization of higher-form symmetries.
A central question in modern quantum matter is not merely *which* topological phases exist, but *how* and *when* they become accessible — the dynamical, microscopic, and symmetry-theoretic conditions under which topological order can actually emerge, be diagnosed, or be destroyed. This synthesis identifies a structural pattern across five specific findings from recent cond-mat.str-el, cond-mat.dis-nn, and cond-mat.mes-hall preprints: (1) non-Hermitian delocalization generically realizes random Dirac criticality in 1D, providing a topological mechanism for criticality without fine-tuning [corpus:arxiv:2606.12089]; (2) the fate of symmetry-protected topological order under nonequilibrium drives is governed by excitation density rather than by which phase regime is entered, with Kibble-Zurek defect production as the decisive control parameter [corpus:arxiv:2606.11303]; (3) exceptional points in interacting non-Hermitian systems amplify charge-density-wave instabilities under open boundary conditions, demonstrating that non-Hermitian boundary topology actively reshapes interaction-driven phase competition [corpus:arxiv:2606.06466]; (4) sequential-circuit invariants of non-invertible symmetry defects provide a purely operator-theoretic diagnostic of 't Hooft anomalies and identify genuinely new loop excitations with non-Abelian fermionic statistics in (3+1)D [corpus:arxiv:2606.11527]; and (5) deconfined quantum critical points in spin chains with Lieb-Schultz-Mattis anomalies are dual, via gauging, to spontaneous breaking of non-invertible symmetries, with the full fusion category — not merely the fusion ring — encoding inequivalent universality classes [corpus:arxiv:2606.05856, corpus:arxiv:2606.06343]. The synthesis argues, as a heuristic reading rather than a derivation, that excitation production, boundary-condition sensitivity, and categorical symmetry structure constitute three interlocking control axes for topological order accessibility. A concrete falsification path is proposed for each claim. The abstract-only reading methodology is acknowledged as a structural limitation throughout. --- Authorship: Saluca Agentic AI Research Team (Saluca LLC). AI-drafted from arXiv preprint corpus on the date in the filename. Cited arXiv preprints: 2605.27166, 2605.29745, 2605.29875, 2606.04651, 2606.04748, 2606.04958, 2606.05856, 2606.06343, 2606.06412, 2606.06432, 2606.06466, 2606.07041, 2606.07241, 2606.07247, 2606.08558, 2606.08805, 2606.09759, 2606.11048, 2606.11303, 2606.11527, 2606.12089, 2606.12353