Abstract Weyl semimetals (WSMs) are topological quantum states wherein the electronic bands disperse linearly around pairs of nodes with fixed chirality, points. In WSMs, nonorthogonal electric and magnetic fields induce an exotic phenomenon known as chiral anomaly, resulting in unconventional negative longitudinal magnetoresistance, chiral-magnetic effect. However, it remains open question to which extent this effect survives when chirality is not well-defined. Here, we establish detailed...

An important and incompletely answered question is whether a closed quantum system of many interacting particles can be localized by disorder. The time evolution simple (unentangled) initial states studied numerically for spinless fermions in one dimension described the random-field XXZ Hamiltonian. Interactions induce dramatic change propagation entanglement smaller particles. For even weak interactions, when thought to many-body phase, shows neither nor diffusive behavior but grows without...

Many-body localization occurs in isolated quantum systems when Anderson persists the presence of finite interactions. Despite strong evidence for existence a many-body transition, reliable extraction critical disorder strength is difficult due to large drift with system size studied quantities. In this Letter, we explore two entanglement properties that are promising study transition: variance half-chain entropy exact eigenstates and long time change after local quench from an eigenstate. We...

We numerically calculate the conductivity $\sigma$ of an undoped graphene sheet (size $L$) in limit vanishingly small lattice constant. demonstrate one-parameter scaling for random impurity scattering and determine function $\beta(\sigma)=d\ln\sigma/d\ln L$. Contrary to a recent prediction, flow has no fixed point ($\beta>0$) conductivities up beyond symplectic metal-insulator transition. Instead, data supports alternative which at Dirac increases logarithmically with sample size absence...

We show that the one-particle density matrix $\rho$ can be used to characterize interaction-driven many-body localization transition in closed fermionic systems. The natural orbitals (the eigenstates of $\rho$) are localized phase and spread out when one enters delocalized phase, while occupation spectrum set eigenvalues reveals distinctive Fock-space structure eigenstates, exhibiting a step-like discontinuity phase. associated entropy is small large with diverging fluctuations at...

We address the breakdown of bulk-boundary correspondence observed in non-Hermitian systems, where open and periodic systems can have distinct phase diagrams. The be completely restored by considering Hamiltonian's singular value decomposition instead its eigendecomposition. This leads to a natural topological description terms flattened decomposition. is equivalent usual approach for Hermitian coincides with recent proposal classification systems. generalize notion entanglement spectrum show...

A direct signature of electron transport at the metallic surface a topological insulator is Aharonov-Bohm oscillation observed in recent study ${\mathrm{Bi}}_{2}{\mathrm{Se}}_{3}$ nanowires [Peng et al., Nature Mater. 9, 225 (2010)] where conductance was found to oscillate as function magnetic flux $\ensuremath{\phi}$ through wire, with period one quantum ${\ensuremath{\phi}}_{0}=h/e$ and maximum zero flux. This seemingly agrees neither diffusive theory, which would predict half quantum, nor...

We propose an easily implemented approach to study time-dependent correlation functions of one-dimensional systems at finite-temperature $T$ using the density matrix renormalization group. The entanglement growth inherent any calculation is significantly reduced if auxiliary degrees freedom which purify statistical operator are time evolved with physical Hamiltonian but reversed time. exploit this investigate long-time behavior current $XXZ$ spin-$1/2$ Heisenberg chain. This allows a direct...

We study superconducting states of doped inversion-symmetric Weyl semimetals. Specifically, we consider a lattice model realizing semimetal with an inversion symmetry and the instability in presence short-ranged attractive interaction. With phonon-mediated interaction, find two competing states: fully gapped finite-momentum (FFLO) pairing state nodal even-parity state. show that, BCS-type approximation, is energetically favored over usual paired robust against weak disorder. Though...

Topological insulators have an insulating bulk but a metallic surface. In the simplest case, surface electronic structure of 3D topological insulator is described by single 2D Dirac cone. A fermion cannot be realized in isolated system with time-reversal symmetry, rather owes its existence to properties wavefunctions. The transport such state are considerable current interest; they some similarities graphene, which also realizes fermions, several unique features their response magnetic...

A potential step in a graphene nanoribbon with zigzag edges is shown to be an intrinsic source of intervalley scattering -- no matter how smooth the on scale lattice constant a. The valleys are coupled by pair localized states at opposite edges, which act as attractor/repellor for edge propagating valley K/K'. relative displacement Delta along ribbon determines conductance G. Our result G=(e^{2}/h)[1-\cos(N\pi+2\pi\Delta/3a)] explains why ``valley-valve'' effect (the blocking current p-n...

We compare the conductance of an undoped graphene sheet with a small region subject to electrostatic gate potential for cases that dynamics in gated is regular (disc-shaped region) and classically chaotic (stadium). For disc, we find sharp resonances narrow upon reducing area fraction region. relate this observation existence confined electronic states. stadium, loses its dependence on voltage region, which signals lack confinement Dirac quasiparticles classical electron dynamics.

We demonstrate evidence of a surface gap opening in topological insulator (TI) thin films (Bi(0.57)Sb(0.43))(2)Te(3) below six quintuple layers through transport and scanning tunneling spectroscopy measurements. By effective tuning the Fermi level via gate-voltage control, we unveil striking competition between weak localization antilocalization at low magnetic fields nonmagnetic ultrathin films, possibly owing to change net Berry phase. Furthermore, when is swept into samples, overall...

Weak topological insulators have an even number of Dirac cones in their surface spectrum and are thought to be unstable disorder, which leads insulating surface. Here we argue that the presence disorder alone will not localize states; rather, a time-reversal symmetric mass term is required for localization. Through numerical simulations, show absence always flow stable metallic phase conductivity obeys one-parameter scaling relation, just as case strong insulator With inclusion mass,...

The Zak phase $\gamma$, the generalization of Berry to Bloch wave functions in solids, is often used characterize inversion-symmetric 1D topological insulators; however, since its value can depend on choice real-space origin and unit cell, only difference between two regions believed be relevant. Here, we show that one extract an origin-independent part so-called inter-cellular $\gamma^{\mathrm{inter}}$, which as a bulk quantity predict number surface modes follows: neutral finite...

We study the ground state phase diagram of quantum spin-2 XXZ chain in presence on-site anisotropy using a matrix-product based infinite system density-matrix-renormalization-group (iDMRG) algorithm. One interests this is connecting highly mechanical spin-1 with classical S=infinity diagram. Several recent advances within DMRG make it possible to perform detailed analysis whole consider different types anisotropies which allows us establish validity following statements: One, model can be...

We study the dynamics of thermalization following a quantum quench using tensor-network methods. Contrary to common belief that rapid growth entanglement and resulting exponential bond dimension restricts simulations short times, we demonstrate long time limit local observables can be well captured time-dependent variational principle. This allows extract transport coefficients such as energy diffusion constant from with rather small dimensions. further characteristic chaotic wave precedes...

The many-body localization transition is a dynamical quantum phase between localized and an extended phase. We study this in the XXZ model with disordered magnetic field focus on time evolution following global quench. While dynamics of bipartite entanglement spin fluctuations are already known to provide insights into nature phases, we discuss relevance these quantities context transition. In particular, observe that near long limits both show behavior similar divergent thermodynamic fluctuations.

The bulk-boundary correspondence, a topic of intensive research interest over the past decades, is one quintessential ideas in physics topological quantum matter. Nevertheless, it has not been proven all generality and certain scenarios even shown to fail, depending on boundary profiles terminated system. Here, we introduce bulk numbers that capture exact number in-gap modes, without any such subtleties spatial dimension. Similarly, based these 1D numbers, define new 2D winding number, which...

We demonstrate that the quantum mutual information (QMI) is a useful probe to study many-body localization (MBL). First, we focus on detection of metal-insulator transition for two different models, noninteracting Aubry-André-Harper model and spinless fermionic disordered Hubbard chain. find QMI in localized phase decays exponentially with distance between regions traced out, allowing us define correlation length, which converges length case one particle. Second, show how can be used as...

We study the properties of entanglement spectrum in gapped non-interacting non-Hermitian systems, and its relation to topological system Hamiltonian. Two different families Hamiltonians can be defined depending on whether we consider only right (or equivalently left) eigenstates or a combination both left eigenstates. show that their spectra still computed efficiently, as Hermitian limit. discuss how symmetries Hamiltonian map into choice many-body state. Through several examples one two...

In the thermal Hall and Nernst effects, electric heat currents, respectively, are induced perpendicular to an applied temperature gradient. Usually, such a response requires application of magnetic field. contrast, here authors establish that in Weyl semimetals -- with linear conical energy dispersion around set points called nodes effect can be realized without field, provided cones tilted. This is anomalous effect. It significantly altered by tilt cones, Fermi surface contributions...

Finite-temperature transport properties of one-dimensional systems can be studied using the time dependent density matrix renormalization group via introduction auxiliary degrees freedom which purify thermal statistical operator. We demonstrate how numerical effort such calculations is reduced when physical evolution augmented by an additional within Hilbert space. Specifically, we explore a variety integrable and non-integrable, gapless gapped models at temperatures ranging from T = ∞ down...

We study interacting fermions in one dimension subject to random, uncorrelated onsite disorder, a paradigmatic model of many‐body localization (MBL). This realizes an interaction‐driven quantum phase transition between ergodic and localized phase, with the occurring eigenstates. propose single‐particle framework characterize these phases by eigenstates (the natural orbitals) eigenvalues occupation spectrum) one‐particle density matrix (OPDM) individual As main result, we find that orbitals...