arXiv subjects

Taylor L. Hughes

Publications and source records attributed to Taylor L. Hughes.

At least 19 recordsLinked to original sources

arXiv2026

Transparent Domain Walls through Information Convex Sets

In $(2+1)$-dimensional topologically ordered many-body states, transparent (topologically deformable) domain walls are invisible to local topological probes, yet can modify the ground state degeneracy (GSD) and transmute anyons transported across them. Here, we develop an entanglement-bootstrap framework using information convex sets (ICSs) on local and noncontractible annuli to extract information about transparent domain walls directly from ground state wavefunctions at fixed points of Abelian topological phases on a torus, without taking categorical defect data as input. We derive fusion rules governing the action of anyons on extreme points of ICSs on noncontractible annuli and determine their quantum dimensions. Extreme points invariant under transport around the complementary cycle correspond one-to-one to minimum entropy states (MESs), and their number equals the GSD. The maximal topological entanglement entropy (TEE), $γ_{\rm LW}^{\max}=\log({D}/d_α)$, probes the net effect of walls crossing the chosen annulus, where ${ D}$ is the total quantum dimension and $d_α$ is the quantum dimension of an extreme point of its ICS. In contrast, the maximal entanglement asymmetry is $ΔS_X^{\max}=\log\mathrm{GSD}$. This value is the same for both annulus orientations and reflects the combined effect of the transparent domain walls. We further show that transparent domain walls can give rise to symmetries supported jointly on the two chosen fundamental cycles that cannot be decomposed into a product of two $1$-form symmetry operators, one supported on each cycle. By relating their action on MESs to anyon tunneling and the fusion rules, we clarify how these symmetries connect distinct ground states. Additionally, we apply the framework to Wen's plaquette model, the anisotropic dipolar toric code, and the rank-2 toric code.

quant-ph↗

arXiv2026

Re-entrant p-wave superconductivity in a Chern Dartboard Insulator

We formulate an exact theory for a 2-band superconductor with inter-orbital pairing and band Hatsugai-Kohmoto (HK) interactions. We apply this theory to a Chern dartboard insulator and compute the pair susceptibility and pair correlations analytically. We find that in the insulating phase previously predicted by BCS theory (small pairing strength $g$, chemical potential $μ$ in the gap), the HK interaction can induce superconductivity, and possibly a Chern dartboard superconductor, by lifting the doubly-occupied band and making it cross the chemical potential. From this HK-induced superconductor, we notice that in a significant parameter range (HK interaction strength $U = 1$, $μ= 0.5$), an insulator-superconductor-insulator re-entrant transition exists. We isolate the re-entrance to a conflation between HK interactions and inter-orbital pairings.

cond-mat.str-el↗

arXiv2026

Higher-form entanglement asymmetry and topological order

We extend a recently defined measure of symmetry breaking, the entanglement asymmetry, to higher-form symmetries. In particular, we focus on Abelian topological order in two dimensions, which spontaneously breaks a 1-form symmetry. Using the toric code as a primary example, we compute the entanglement asymmetry and compare it to the topological entanglement entropy. We find that while the two quantities are not strictly equivalent, both are sub-leading corrections to the area law and can serve as order parameters for the topological phase. We generalize our results to non-chiral Abelian topological order and express the maximal entanglement asymmetry in terms of the quantum dimension. Finally, we discuss how the scaling of entanglement asymmetry correctly detects topological order in the deformed toric code, where 1-form symmetry breaking persists even in a trivial phase.

cond-mat.str-el↗

arXiv2026

The Fate of Crystalline Topological Phenomena in the Continuum

The continuum limit is a widely used theoretical construct for obtaining continuum field-theories of crystalline systems. We study the formulation of a continuum limit for gapped bosonic phases and ask whether their topological properties survive passage to the continuum. Using methods in algebraic topology and category theory, we give a rigorous formulation of the continuum limit and construct a surjective global map relating crystalline topological phases across all finite point-group symmetries to continuum invertible topological phases. Consequently, we find that some lattice phases admit no continuum limit, while distinct lattice phases that do admit a continuum limit can share the same continuum image, hence implying that some lattice topological data can collapse. Conversely, we find that every continuum invertible phase admits a faithful crystalline realization. In addition to the general framework, we apply it to several examples, including studies of a 2D rotation-symmetric phase, higher-order topological phases, and the mixed spin-lattice anomaly of the deconfined quantum critical point between an antiferromagnet and valence bond solid.

cond-mat.str-el↗

arXiv2026

Symmetry-protected cubic-touching topological surface bands with tunable singularities

We propose a class of topological surface bands in three-dimensional topological crystalline insulators that have symmetry-protected cubic-order band touching. Within the symmetry constraint, the band dispersion can continuously vary between cubic dispersion, moat band and multi-mini-valley structure with van Hove singularities by adjusting particle-hole asymmetry and anisotropy. Thus, there is a family of tunable density-of-state singularities ranging from power-law to logarithmic divergences. This offrs a versatile platform for engineering strongly correlated phases of matter in topological surface states. We provide an example realization in a prism-lattice tight-binding model of angular-momentum-3/2 electrons.

cond-mat.str-el↗

arXiv2026

Fragile Topology is Unstable Under Translation Refinement

Fragile topological phases become trivial upon the addition of suitable trivial bands, distinguishing them from stable topological phases. Nevertheless, various response phenomena and material realizations have been proposed for fragile phases. At the same time, many of these phenomena can also occur in atomic insulators, leaving open the question of what properties are specific to fragile phases. Enlarging the unit cell offers a natural perspective on this question. Band folding increases the number of bands in a manner analogous to adding trivial bands. In this work, we establish a systematic framework for determining the stability of fragile topology under unit-cell enlargement. We first establish a systematic criterion for trivialization under enlargements compatible with space-group symmetry, grounded in a physical electron-positron picture and formulated through a Hilbert-basis analysis of momentum-space symmetry data. We then show that, for all two-dimensional wallpaper groups, with or without spin-orbit coupling and/or time-reversal symmetry, every symmetry-indicated fragile phase is adiabatically connected to an atomic insulator in a suitable finite supercell and can therefore be trivialized by an arbitrarily small symmetry-preserving perturbation. Our results reveal that fragile topology has only finite stability under translation-symmetry refinement. This highlights that the fate of a fragile phase can depend on translation-symmetry-breaking perturbations, such as charge-density-wave ordering, and suggests that physical signatures insensitive to translation refinement are unlikely to uniquely characterize fragile topology.

cond-mat.mes-hall↗

arXiv2026

Domain wall motion in a polycrystalline vortex lattice

Disorder fundamentally reshapes how crystalline systems respond to external forces, yet it remains unclear whether disorder drives interacting lattices toward glassy states or instead fragments them into domains separated by mobile interfaces. Here, we investigate vortex motion in superconducting island arrays, where disorder is introduced in a controlled manner by tuning the magnetic field away from commensurate vortex fillings. By driving vortices with an applied current, we observe a two-step depinning transition at incommensurate fillings. Comparison with molecular vortex model simulations shows that this intermediate regime is consistent with domain wall motion in a polycrystalline vortex lattice. While two-step depinning has been explored theoretically in driven periodic systems, direct experimental evidence linking this behavior to interface-dominated vortex motion has been lacking. Our results demonstrate that disordered, interacting vortex systems with strong periodic pinning can favor interface physics over homogeneous glassy dynamics.

cond-mat.supr-con↗

arXiv2026

Non-Hermitian Multipole Skin Effects Challenge Localization

We study the effect of quenched disorder on the non-Hermitian skin effect in systems that conserve a U(1) charge and its associated multipole moments. In particular, we generalize the Hatano-Nelson argument for a localization transition in disordered, non-reciprocal systems to the interacting case. When only U(1) charge is conserved, we show that there is a transition between a skin effect phase, in which charges cluster at a boundary, and a many-body localized phase, in which charges localize at random positions. In the dynamics of entanglement, this coincides with an area to volume law transition. For systems without boundaries, the skin effect becomes a delocalized phase with a unidirectional current. If dipoles or higher multipoles are conserved, we show that the non-Hermitian skin effect remains stable to arbitrary disorder. Counterintuitively, the system is therefore always delocalized under periodic boundary conditions, regardless of disorder strength.

cond-mat.dis-nn↗

arXiv2026

Non-zero Momentum Implies Long-Range Entanglement When Translation Symmetry is Broken in 1D

A result by Gioia and Wang [Phys Rev X 12, 031007 (2022)] showed that translationally symmetric states having nonzero momentum are necessarily long range entangled (LRE). Here, we consider the question: can a notion of momentum for non-translation symmetric states directly encode the nature of their entanglement, as it does for translation symmetric states? We show the answer is affirmative for 1D systems, while higher dimensional extensions and topologically ordered systems require further work. While Gioia and Wang's result applies to states connected via finite depth quantum circuits to a translation symmetric state, it is often impractical to find such a circuit to determine the nature of the entanglement of states that break translation symmetry. Here, instead of translation eigenstates, we focus on the many-body momentum distribution and the expectation value of the translation operator in many-body states of systems having broken translation symmetry. We show that in the continuum limit the magnitude of the expectation value of the translation operator $| |$ necessarily goes to $1$ for delocalized states, a proxy for LRE states in 1D systems. This result can be seen as a momentum-space version of Resta's formula for the localization length. We investigate how accurate our results are in different lattice models with and without well-defined continuum limits. To that end, we introduce two models: a deterministic version of the random dimer model, illustrating the role of the thermodynamic and continuum limits for our result at a lattice level, and a simplified version of the Aubry-Andre model, with commensurate hopping for both momentum and position space. Finally, we use the random dimer model as a test case for the accuracy of $| |$ as a localization (and thus entanglement) probe for 1D periodic lattice models without a well-defined continuum limit.

cond-mat.dis-nn↗

arXiv2026

Spin-momentum Locking and Topological Vector Charge Response with Conserved Spin

Spin-momentum locking plays a fundamental role in spintronics and, more broadly, is an important concept in condensed matter physics. In 2D and 3D, spin-momentum locking typically does not allow spin-conservation because the spin-1/2 operators of electrons anticommute. Instead, here we study spin-momentum locking terms with conserved, commuting pseudospins built from a combination of spin and orbitals. We find that 2D spin-momentum locking terms with conserved pseudospins generally lead to linearly dispersing modes at low-energy with anomalous charge and pseudospin currents. To cure the anomaly we show that such anomalous modes can be realized on the surface of a 3D Weyl semimetal (or an associated weak topological insulator) with a nonzero mixed spin-momentum quadrupole moment, which is determined by the momentum location and pseudospin eigenvalues of Weyl points at the Fermi level. Crucially, this mixed quadrupole moment captures a mixed pseudospin-charge bulk response that cancels the anomaly of surface modes, and can generate a giant 3D spin Hall effect, among other phenomena.

cond-mat.mes-hall↗

arXiv2025

Preparation of a Quantum Spin Liquid in Non-Hermitian Quantum Dimer Models and Rydberg Arrays

We identify an unconventional form of the non-Hermitian skin effect that occurs not in position space but in many-body Fock space, which we call the Fock space skin effect (FSSE). Using quantum dimer models, we characterize FSSE analytically and numerically, and propose a concrete route toward its realization in Rydberg atom arrays. The dimer constraint is enforced through Rydberg gadgets employing the blockade mechanism, while directional reservoirs generate non-Hermitian flipping amplitudes. We show that FSSE enables the preparation of gapped spin liquid states, and in particular, we demonstrate how a Rydberg geometry realizing a square lattice quantum dimer model with next-nearest neighbor dimers can be driven by non-Hermiticity into an exact spin liquid ground state. Our results establish Fock-space non-Hermiticity as a powerful principle for engineering exotic quantum phases and dynamical state-preparation protocols.

cond-mat.str-el↗

arXiv2025

Chern Dartboard Superconductors

We investigate the interplay of particle-hole symmetry and sub-Brillouin zone (sBZ) topology by coupling a so-called Chern dartboard insulator (CDI) to a superconductor (SC) via the proximity effect. We dub the hybrid system, and equivalent intrinsically superconducting phases, a \emph{Chern dartboard superconductor} (CDSC). We show that a CDSC can have nontrivial sBZ topology if it arises from a CDI that has an even number of mirror symmetries $n$. On the other hand, particle-hole symmetry constrains a CDSC that arises from an odd-$n$ CDI to have trivial sBZ topology. However, we can circumvent this constraint for $n=1$ by inducing an FFLO-type pairing or shifting the CDI in momentum space, converting the mirror symmetry to a momentum-space nonsymmorphic mirror symmetry. With a superconducting pairing that preserves the (nonsymmorphic) mirror symmetries, even-$n$ CDIs and the shifted $n=1$ CDI can realize the minimal spinless phase that has a trivial total Chern number and nontrivial reduced Chern numbers. With a pairing that breaks the mirror symmetries, the hybrid system can realize phases that have nontrivial total and reduced Chern numbers, expanding the classification of phases that have sub-Brillouin zone (sBZ) topology. We also predict that some types of $n=2$ CDSCs inherit the quantized crystalline response of the $n=2$ CDI, providing experimentalists with a well-defined way to probe the CDSC. Our work motivates further exploration of sBZ topology, bulk topology, and quantized response.

cond-mat.supr-con↗

arXiv2025

Global and Local Topological Crystalline Markers for Rotation-Symmetric Insulators

Crystalline symmetry can be used to predict bulk and surface properties of topological phases. For non-interacting cases, symmetry-eigenvalue analysis of Bloch states at high symmetry points in the Brillouin zone simplifies the calculation of topological quantities. However, when open boundaries are present, and only the point group part of the symmetry group remains, it is unclear how to utilize crystalline symmetries to diagnose band topology. In this work, we introduce topological crystalline markers to characterize bulk topology in $C_n$-symmetric ($n=2,3,4,6$) crystalline insulators and superconductors with and without translation symmetry. These markers are expressed using a crystalline symmetry operator and the ground state projector, and are defined locally in position space. First, we provide a general method to calculate topological markers in periodic systems with an arbitrary number of unit cells. This includes cases where momentum quantization does not span all necessary high-symmetry points for computing the topological quantities, which we address using twisted boundary conditions. Second, we map these markers to the Chern number, bulk polarization, and sector charge for two-dimensional $C_n$-symmetric insulators in symmetry classes A, AI, AII, and superconductors in class D. Finally, we show how to numerically calculate the markers in finite-size systems with translation-symmetry (and even rotation-symmetry) breaking defects, and how to diagnose the bulk topology from the marker. Our results demonstrate how to compute bulk topological crystalline invariants locally in position space, thereby providing broader scope to diagnosing bulk crystalline topology that works even in inhomogeneous systems where there is no global rotation symmetry.

cond-mat.mes-hall↗

arXiv2025

No-go theorem for single time-reversal invariant symmetry-protected Dirac fermions in 3+1d

We employ a general method, known as anomaly-matching, to derive new no-go theorems of fermionic lattice models. For our main result, we show that time-reversal invariant 3+1d lattice systems (such as Dirac and Weyl semimetals) can never admit a lone low-energy symmetry-protected Dirac fermion (or node), i.e., it must always come in higher muliplets or be fine-tuned. This theorem holds for both non-interacting and interacting systems as long as the electromagnetic $U(1)_{V,{\rm UV}}$ symmetry is a normal subgroup of the microscopic symmetry group $G_{\mathrm{UV}}$; a condition that is ubiquitous in physical $U(1)_{V,{\rm UV}}$ preserving lattice models. To show that our theorems are tight, we also explore both well-known and new systems that are converses of the no-go theorem, obtained by forfeiting certain assumptions such as a broken time-reversal symmetry (magnetic Weyl semimetal), a non-compact non-on-site $U(1)$ (almost local Dirac node model), no-symmetry protection (fine-tuned Dirac semimetal), or multiple low-energy Dirac nodes (time-reversal invariant Weyl and Dirac semimetals). We will also explicitly demonstrate that, while this theorem strictly prohibits single time-reversal invariant symmetry-protected Dirac node, it does allow for other odd numbers of Dirac nodes under certain circumstances, such as three Dirac nodes in the Fu-Kane-Mele diamond lattice model. This is akin to the Nielsen-Ninomiya theorem for an odd number of differently-charged chiral fermions, whose lattice realizations are allowed if certain anomaly cancellation conditions are met.

cond-mat.str-el↗

arXiv2025

Quantized crystalline-electromagnetic responses in insulators

We introduce new classes of gapped topological phases characterized by quantized crystalline-electromagnetic responses, termed "multipolar Chern insulators". These systems are characterized by nonsymmorphic momentum-space symmetries and mirror symmetries, leading to quantization of momentum-weighted Berry curvature multipole moments. We construct lattice models for such phases and confirm their quantized responses through numerical calculations. These systems exhibit bound charge and momentum densities at lattice and magnetic defects, and currents induced by electric or time-varying strain fields. Our work extends the classification of topological matter by uncovering novel symmetry-protected topological phases with quantized responses.

cond-mat.mes-hall↗

arXiv2025

Gapless Fermionic Systems as Phase-space Topological Insulators: Non-perturbative Results from Anomalies

We present a theory unifying the topological responses and anomalies of various gapless fermion systems exhibiting Fermi surfaces, including those with Berry phases, and nodal structures, which applies beyond non-interacting limit. As our key finding, we obtain a general approach to directly relate gapless fermions and topological insulators in phase space, including first- and higher-order insulators. Using this relation we show that the low-energy properties and response theories for gapless fermionic systems can be directly obtained without resorting to microscopic details. Our results provide a unified framework for describing such systems using well-developed theories from the study of topological phases of matter.

cond-mat.str-el↗

arXiv2025

Separate surface and bulk topological Anderson localization transitions in disordered axion insulators

In topological phases of matter for which the bulk and boundary support distinct electronic gaps, there exists the possibility of decoupled mobility gaps in the presence of disorder. This is in analogy with the well-studied problem of realizing separate or concomitant bulk-boundary criticality in conventional Landau theory. Using a three-dimensional axion insulator having clean, gapped surfaces with $e^2/2h$ quantized Hall conductance, we show the bulk and surface mobility gap evolve differently in the presence of disorder. The decoupling of the bulk and surface topology yields a regime that realizes a two-dimensional, unquantized anomalous Hall metal in the Gaussian unitary ensemble (GUE), which shares some spectral and response properties akin to the surface states of a conventional three-dimensional (3D) topological insulator. The generality of these results as well as extensions to other insulators and superconductors is discussed.

cond-mat.dis-nn↗

arXiv2024

Giant non-reciprocity and gyration through modulation-induced Hatano-Nelson coupling in integrated photonics

Asymmetric energy exchange interactions, also known as Hatano-Nelson type couplings, enable the study of non-Hermitian physics and associated phenomena like the non-Hermitian skin effect and exceptional points (EP). Since these interactions are by definition non-reciprocal, there have been very few options for real-space implementations in integrated photonics. In this work, we show that real-space asymmetric couplings are readily achievable in integrated photonic systems through time-domain dynamic modulation. We experimentally study this concept using a two-resonator photonic molecule produced in a lithium niobate on insulator platform that is electro-optically modulated by rf stimuli. We demonstrate the dynamic tuning of the Hatano-Nelson coupling between the resonators, surpassing the asymmetry that has been achieved in previous work, to reach an EP for the first time. We are additionally able to flip the relative sign of the couplings for opposite directions by going past the EP. Using this capability, we show that the through-chain transport can be configured to exhibit both giant (60 dB) optical contrast as well as photonic gyration or non-reciprocal pi phase contrast.

physics.optics↗