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Hiroaki Matsueda

Publications and source records attributed to Hiroaki Matsueda.

At least 55 records · Page 3Linked to original sources
arXiv2015

Exact-Diagonalization Analysis of Composite Excitations in the t-J Model

We examine spectral properties of doped holes dressed with surrounding spin cloud in the t-J model. These composite-hole excitations well characterize prominent band structures in the angle-resolved photoemission spectrum. In one-dimensional (1D) case at half-filling, we identify the composite operators that separately pick up the spinon and holon branches, respectively. After hole doping, we find that the composite hole excitations with string-like spins tend to be localized at k=π/2 in the momentum space. This means that such composite excitations should be actual electronic excitations, since the spinon and holon branches merge together at this momentum. In 2D case, we find that the composite excitations with more non-local spin fluctuation have stronger intensity near the Fermi level. The composite band structure along diagonal (0,0)-(π,π) direction in 2D has some similarity to that in 1D, and such non-local spin fluctuation plays an important role on the formation of the pseudogap in high-Tc cuprates.

cond-mat.str-el↗
arXiv2015

Entropy of Factorized Snapshot Data for Two-Dimensional Classical Spin Models

We reexamine the snapshot entropy of the Ising and three-states Potts models on the LxL square lattice. Focusing on the factorization of the snapshot matrix, we find that the entropy at Tc scales asymptotically as S=(c/3)lnL consistent with the entanglement entropy in one-dimensional quantum critical systems. This nontrivial consistency strongly supports that the snapshot entropy after the factorization really represents the holographic entanglement entropy. On the other hand, the anomalous scaling for the coarse-grained snpshot entropy is retained even after the factorization. These fearures are considered to originate from the fact that the largest singular value of the snapshot matrix is regulated by the factorization.

cond-mat.stat-mech↗
arXiv2014

Photo-Induced Dynamics in Charge-Frustrated Systems

Photo-excited charge dynamics of interacting charge-frustrated systems are studied using a spinless fermion model on an anisotropic triangular lattice. Real-time evolution of the system after irradiating a pump-photon pulse is analyzed by the exact diagonalization method. We focus on photo-excited states in the two canonical charge-ordered (CO) ground states, i.e., horizontal stripe-type and vertical stripe-type COs, which compete with each other owing to the charge frustration. We find that the photo-induced excited states from the two types of COs are distinct. From the horizontal stripe-type CO, a transition to another CO state called the three-fold CO phase occurs. In sharp contrast, the vertical stripe-type CO phase is only weakened by photo-irradiation. Our observations are attributable to the charge frustration effects occurring in the photo-excited states.

cond-mat.str-el↗
arXiv2014

BTZ Black Hole in Fisher Information Spacetime

We examine whether we can make a black hole in Fisher information spacetime and what kind of quantum states produce the black hole solution in terms of the anti-de Sitter spacetime/conformal field theory correspondence. Here we focus on the Banados-Teitelboim-Zanelli black hole. There exists a mathematical representation of entanglement spectra that define the Fisher geometry as the black hole spacetime. We find that this representation is quite similar to the entanglement spectra in a conformal field theory at finite temperature except for minor corrections, and then the inverse temperature corresponds to the position of the event horizon in the Poincare coordinate.

hep-th↗
arXiv2014

Geodesic Distance in Fisher Information Space and Holographic Entropy Formula

In this short note, we examine geodesic distance in Fisher information space in which the metric is defined by the entanglement entropy in CFT_(1+1). It is obvious in this case that the geodesic distance at a constant time is a function of the entropy data embedded into the information space. In a special case, the geodesic equation can be solved analytically, and we find that the distance agrees well with the Ryu-Takayanagi formula. Then, we can understand how the distance looks at the embeded quantum information. The result suggests that the Fisher metric is an efficient tool for constructing the holographic spacetime.

hep-th↗
arXiv2014

Embedding Quantum Information into Classical Spacetime: Information Geometrical Perspectives on anti-de Sitter space / conformal field theory Correspondence

An information-geometrical interpretation of AdS3/CFT2 correspondence is given. In particular, we consider an inverse problem in which the classical spacetime metric is given in advance and then we find what is the proper quantum information that is well stored into the spacetime. We see that the Fisher metric plays a central role on this problem. Actually, if we start with the two-dimensional hyperbolic space, a constant-time surface in AdS3, the resulting singular value spectrum of the quantum state shows power law for the correlation length with conformal dimension proportional to the curvature radius in the gravity side. Furthermore, the entanglement entropy data embedded into the hyperbolic space agree well with the Ryu-Takayanagi formula. These results show that the relevance of the AdS/CFT correspondence can be represented by the information-gemetrical approach based on the Fisher metric.

hep-th↗
arXiv2014

Information Geometry for Husimi-Temperley Model

We examine phase transition of the Husimi-Temperley model in terms of information geometry. For this purpose, we introduce the Fisher metric defined by the density matrix of the model. We find that the metric becomes hyperbolic at the critical point with respect to the energy scale. Then, the metric is invariant under the scale transformation. We also find that the equation of states is naturally derived from a necessary condition for the entropy operator that is a building block of the metric. Based on these findings, we conclude that the geometric quantities clearly detect the phase transition of the model.

cond-mat.stat-mech↗
arXiv2014

Exact Mapping from Singular Value Spectrum of Fractal Images to Entanglement Spectrum of One-Dimensional Quantum Systems

We examine the snapshot entropy of general fractal images defined by their singular values. Remarkably, the singular values for a large class of fractals are in exact correspondence with the entanglement spectrum of free fermions in one dimension. These fermions allow for a holographic interpretation of the logarithmic scaling of the snapshot entropy, which is in agreement with the Calabrese-Cardy formula. However, the coarse-grained entropy exhibits a linear scaling due to the degeneracy of the spectrum, in contrast with the logarithmic scaling behavior in one-dimensional quantum near-critical systems.

cond-mat.stat-mech↗
arXiv2013

Emergent General Relativity from Fisher Information Metric

We derive the Einstein tensor from the Fisher information metric that is defined by the probability distribution of a statistical mechanical system. We find that the tensor naturally contains essential information of the energy-momentum tensor of a classical scalar field, when the entropy data or the spectrum data of the system are embedded into the classical field as the field strength. Thus, we can regard the Einstein equation as the equation of coarse-grained states for the original microscopic system behind the classical field theory. We make some remarks on quantization of gravity and various quantum-classical correspondences.

gr-qc↗
arXiv2012

Photoinduced spin-order destructions in one-dimensional extended Hubbard model

By employing the time-dependent Lanczos method, the nonequilibrium process of the half-filled one-dimensional extended Hubbard model under the irradiation of a transient laser pulse is investigated. We show that in the spin-density-wave (SDW) phase, the antiferromagnetic spin correlations are impaired by the photoinduced charge carriers. Near the phase boundary between the SDW and charge-density-wave (CDW) phases, a local enhancement of charge (spin) order that is absent in the original SDW (CDW) phase can be realized with proper laser frequency and strength. The possibility of restoration of spin orders from the CDW phase by optical means is discussed.

cond-mat.str-el↗
arXiv2012

Enhanced charge order in a photoexcited one-dimensional strongly correlated system

We present a compelling response of a low-dimensional strongly correlated system to an external perturbation. Using the time-dependent Lanczos method we investigate a nonequilibrium evolution of the half-filled one-dimensional extended Hubbard model, driven by a transient laser pulse. When the system is close to the phase boundary, by tuning the laser frequency and strength, a sustainable charge order enhancement is found that is absent in the Mott insulating phase. We analyze the conditions and investigate possible mechanisms of emerging charge order enhancement. Feasible experimental realizations are proposed.

cond-mat.str-el↗
arXiv2012

VBS/CFT Correspondence and Thermal Tensor Network

It has been recently observed that the reduced density matrix of a two-dimensional (2D) valence bond solid state can be mapped onto the thermal density matrix of a 1D Heisenberg quantum spin chain. Motivated by the observation, I propose a very simple phenomenological theory for this type of correspondence based on a finite-temperature tensor network formalism recently developed. I adress close relationship and sharp difference between the present correspondence and multiscale entanglement renormalization ansatz in terms of network geometry.

cond-mat.stat-mech↗
arXiv2012

Topology and Geometric Structure of Branching MERA Network

We examine a bulk-edge correspondence of branching MERA networks at finite temperatures in terms of algebraic and differential topology. By using homeomorphic mapping, we derive that the networks are nonorientable manifolds such as a M$\ddot{\rm o}$bius strip and a Klein bottle. We also examine the stability of the branch in connection with the second law of black hole thermodynamics. Then, we prove that the MERA network for one-dimensional quantum critical systems spontaneously separates into multiple branches in the IR region of the network. On the other hand, the branch does not occur in more than two dimensions. The result illustrates dimensionality dependence of spin-charge separation / coupling. We point out a role of twist of the surfaces on the phase string between spinon and holon excitations.

cond-mat.stat-mech↗
arXiv2012

Multiscale Entanglement Renormalization Ansatz for Kondo Problem

We derive the multiscale entanglement renormalization ansatz (MERA) for the single impuity Kondo model. We find two types of hidden quantum entanglement: one comes from a finite-temperature effect on the geometry of the MERA network, and the other represents screening of the impurity by conduction electrons. As the latter starts to dominate the electronic state, the Kondo physics emerges. The present result is a simple and beautiful example of a holographic dual of a boundary conformal field theory.

cond-mat.stat-mech↗
arXiv2012

Tensor Network and Black Hole

A tensor network formalism of thermofield dynamics is introduced. The formalism relates the original Hilbert space with its tilde space by a product of two copies of a tensor network. Then, their interface becomes an event horizon, and the logarithm of the tensor rank corresponds to the black hole entropy. Eventually, multiscale entanglement renormalization anzats (MERA) reproduces an AdS black hole at finite temperature. Our finding shows rich functionalities of MERA as efficient graphical representation of AdS/CFT correspondence.

hep-th↗
arXiv2012

Relaxation Dynamics of Photocarriers in One-Dimensional Mott Insulators Coupled to Phonons

We examine recombination processes of photocarriers in one-dimensional Mott insulators coupled to phonons. Performing density matrix renormalization group calculations, we find that, even for small electron-phonon coupling, many phonons are generated dynamically, which cause initial relaxation process after the irradiation. At the same time, spin-charge coupling coming from mixing of high- and low-energy states by the irradiation is suppressed. We discuss differences between Mott and band insulators in terms of relaxation dynamics.

cond-mat.str-el↗
arXiv2011

Scaling of entanglement entropy and hyperbolic geometry

Various scaling relations of the entanglement entropy are reviewed. Based on the scaling, I would like to point out similarity of mathematical formulation among recent topics in wide research area. In particular, the scaling plays crucial roles on identifying a quantum system with a physically different classical system. Close connection between the scaling and hyperbolic geometry and contrast between bulk/edge correspondence and compactification for the identification are also addressed.

cond-mat.stat-mech↗