Complex Replica Zeros of $\pm J$ Ising Spin Glass at Zero Temperature (2008)
Obuchi, Tomoyuki, Kabashima, Yoshiyuki, Nishimori, Hidetoshi
Zeros of the $n$th moment of the partition function $[Z^n]$ are investigated in a vanishing temperature limit $\beta \to \infty$, $n \to 0$ keeping $y=\beta n \sim O(1)$. In this limit, the moment...
Quantum annealing for problems with ground-state degeneracy (2008)
Matsuda, Yoshiki, Nishimori, Hidetoshi, Katzgraber, Helmut G
We study the performance of quantum annealing for systems with ground-state degeneracy by directly solving the Schr\"odinger equation for small systems and quantum Monte Carlo simulations for larger...
Mathematical Foundation of Quantum Annealing (2008)
Morita, Satoshi, Nishimori, Hidetoshi
Quantum annealing is a generic name of quantum algorithms to use quantum-mechanical fluctuations to search for the solution of optimization problem. It shares the basic idea with quantum adiabatic...
Spin Glass Identities and the Nishimori Line (2008)
Contucci, Pierluigi, Giardina, Cristian, Nishimori, Hidetoshi
For a general spin glass model with asymmetric couplings we prove a family of identities involving expectations of generalized overlaps and magnetizations in the quenched state. Those identities...
Multicritical points for the spin glass models on hierarchical lattices (2008)
Ohzeki, Masayuki, Nishimori, Hidetoshi, Berker, A. Nihat
The locations of multicritical points on many hierarchical lattices are numerically investigated by the renormalization group analysis. The results are compared with an analytical conjecture derived...
Reentrant and Forward Phase Diagrams of the Anisotropic Three-Dimensional Ising Spin Glass (2008)
Güven, Can, Berker, A. Nihat, Hinczewski, Michael, Nishimori, Hidetoshi
The spatially uniaxially anisotropic d=3 Ising spin glass is solved exactly on a hierarchical lattice. Five different ordered phases, namely ferromagnetic, columnar, layered, antiferromagnetic, and...
Matsuda, Yoshiki, Nishimori, Hidetoshi, Hukushima, Koji
We investigate the distribution of zeros of the partition function of the two- and three-dimensional symmetric $\pm J$ Ising spin glasses on the complex field plane. We use the method to analytically...
Inequalities for the Local Energy of Random Ising Models (2007)
Kitatani, Hidetsugu, Nishimori, Hidetoshi, Aoki, Akira
We derive a rigorous lower bound on the average local energy for the Ising model with quenched randomness. The result is that the lower bound is given by the average local energy calculated in the...
Convergence of Quantum Annealing with Real-Time Schrodinger Dynamics (2007)
Morita, Satoshi, Nishimori, Hidetoshi
Convergence conditions for quantum annealing are derived for optimization problems represented by the Ising model of a general form. Quantum fluctuations are introduced as a transverse field and/or...
Quantum annealing of the random-field Ising model by transverse ferromagnetic interactions (2007)
Suzuki, Sei, Nishimori, Hidetoshi, Suzuki, Masuo
We introduce transverse ferromagnetic interactions, in addition to a simple transverse field, to quantum annealing of the random-field Ising model to accelerate convergence toward the target ground...
Obuchi, Tomoyuki, Nishimori, Hidetoshi, Sherrington, David
The phase diagram of the $p$-spin-interacting spin glass model in a transverse field is investigated in the limit $p \to \infty$ under the presence of ferromagnetic bias. Using the replica method and...
Convergence theorems for quantum annealing (2006)
Morita, Satoshi, Nishimori, Hidetoshi
We prove several theorems to give sufficient conditions for convergence of quantum annealing, which is a protocol to solve generic optimization problems by quantum dynamics. In particular the...
Ohzeki, Masayuki, Nishimori, Hidetoshi
We calculate the internal energy of the Potts model on the triangular lattice with two- and three-body interactions at the transition point satisfying certain conditions for coupling constants. The...
Duality in finite-dimensional spin glasses (2006)
We present an analysis leading to a conjecture on the exact location of the multicritical point in the phase diagram of spin glasses in finite dimensions. The conjecture, in satisfactory agreement...
Nishimori, Hidetoshi, Ohzeki, Masayuki
A conjecture is given for the exact location of the multicritical point in the phase diagram of the +/- J Ising model on the triangular lattice. The result p_c=0.8358058 agrees well with a recent...
Gauge Theory for Quantum Spin Glasses (2005)
Morita, Satoshi, Ozeki, Yukiyasu, Nishimori, Hidetoshi
The gauge theory for random spin systems is extended to quantum spin glasses to derive a number of exact and/or rigorous results. The transverse Ising model and the quantum gauge glass are shown to...
Surface terms on the Nishimori line of the Gaussian Edwards-Anderson model (2005)
Contucci, Pierluigi, Morita, Satoshi, Nishimori, Hidetoshi
For the Edwards-Anderson model we find an integral representation for some surface terms on the Nishimori line. Among the results are expressions for the surface pressure for free and periodic...
Exact location of the multicritical point for finite-dimensional spin glasses: A conjecture (2005)
Takeda, Koujin, Sasamoto, Tomohiro, Nishimori, Hidetoshi
We present a conjecture on the exact location of the multicritical point in the phase diagram of spin glass models in finite dimensions. By generalizing our previous work, we combine duality and...
Possibly Exact Solution for the Multicritical Point of Finite-Dimensional Spin Glasses (2004)
Nishimori, Hidetoshi, Takeda, Koujin, Sasamoto, Tomohiro
After briefly describing the present status of the spin glass theory, we present a conjecture on the exact location of the multicritical point in the phase diagram of finite-dimensional spin glasses....
Error counting in a quantum error-correcting code and the ground-state energy of a spin glass (2004)
Nishimori, Hidetoshi, Sollich, Peter
Upper and lower bounds are given for the number of equivalence classes of error patterns in the toric code for quantum memory. The results are used to derive a lower bound on the ground-state energy...
Griffiths inequalities for the Gaussian spin glass (2004)
Morita, Satoshi, Nishimori, Hidetoshi, Contucci, Pierluigi
The Griffiths inequalities for Ising spin-glass models with Gaussian randomness of non-vanishing mean are proved using properties of the Gaussian distribution and gauge symmetry of the system. These...
Exact Ground-State Energies of the Random-Field Ising Chain and Ladder (2004)
Hamasaki, Toshiyuki, Nishimori, Hidetoshi
We derive the exact ground-state energy of the one-dimensional Ising model in random fields taking values h, 0 and -h with general probabilities. The random-field Ising model on a ladder is also...
Self-dual random-plaquette gauge model and the quantum toric code (2003)
Takeda, Koujin, Nishimori, Hidetoshi
We study the four-dimensional Z_2 random-plaquette lattice gauge theory as a model of topological quantum memory, the toric code in particular. In this model, the procedure of quantum error...
Symmetry, complexity and multicritical point of the two-dimensional spin glass (2003)
Maillard, Jean-Marie, Nemoto, Koji, Nishimori, Hidetoshi
We analyze models of spin glasses on the two-dimensional square lattice by exploiting symmetry arguments. The replicated partition functions of the Ising and related spin glasses are shown to have...
Energy fluctuations at the multicritical point in two-dimensional spin glasses (2002)
Nishimori, Hidetoshi, Falvo, Cyril, Ozeki, Yukiyasu
We study the two-dimensional +/-J Ising model, three-state Potts model and four-state Potts model, by the numerical transfer matrix method to investigate the behaviour of the sample-to-sample...
Absence of the Effects of Vortices in the Gauge Glass (2002)
Hamasaki, Toshiyuki, Nishimori, Hidetoshi
We calculate several correlation functions and distribution functions of dynamical variables for the gauge glass and the Villain model using the spin wave approximation and the gauge transformation....
Derivatives and inequalities for order parameters in the Ising spin glass (2002)
Identities and inequalities are proved for the order parameters, correlation functions and their derivatives of the Ising spin glass. The results serve as additional evidence that the ferromagnetic...
Complex and Non-Complex Phase Structures in Models of Spin Glasses and Information Processing (2002)
The gauge theory of spin glasses and statistical-mechanical formulation of error-correcting codes are reviewed with an emphasis on their similarities. For the gauge theory, we explain the functional...
Exact results on spin glass models (2002)
Exact and/or rigorous results are reviewed for the Ising and XY/Villain spin glasses in finite dimensions, such as the exact energy, correlation identities and a functional relation between the...
西森, 秀稔, ニシモリ, ヒデトシ, Nishimori, Hidetoshi
SMAPIP 2002 科研費特定領域研究「確率的情報処理への統計力学的アプローチ」平成 14 年度研究成果発表会での講演概要
西森, 秀稔, ニシモリ, ヒデトシ, Nishimori, Hidetoshi
SMAPIP 2002 科研費特定領域研究「確率的情報処理への統計力学的アプローチ」平成 14 年度研究成果発表会での講演概要
Duality and Multicritical Point of Two-Dimensional Spin Glasses (2001)
Nishimori, Hidetoshi, Nemoto, Koji
Determination of the precise location of the multicritical point and phase boundary is a target of active current research in the theory of spin glasses. In this short note we develop a duality...
Multispin Ising spin glasses with ferromagnetic interactions (2001)
Gillin, Peter, Nishimori, Hidetoshi, Sherrington, David
We consider the thermodynamics of an infinite-range Ising p-spin glass model with an additional r-spin ferromagnetic interaction. For r=2 there is a continuous transition to a ferromagnetic phase,...
Absence of Replica Symmetry Breaking (2001)
Hidetoshi Nishimori, David Sherrington
We prove that the distribution functions of magnetization and spin glass order parameter coincide on the Nishimori line in the phase diagram of the Ising model in any dimension. This implies absence...
Multispin Ising spin glasses with ferromagnetic interactions (2001)
Peter Gillin, Hidetoshi Nishimori, David Sherrington
We consider the thermodynamics of an infinite-range Ising p-spin glass model with an additional r-spin ferromagnetic interaction. For r = 2 there is a continuous transition to a ferromagnetic phase,...
Stagewise Processing in Error-Correcting (2001)
We introduce stagewise processing in error-correcting codes and image restoration, by extracting information from the former stage and using it selectively to improve the performance of the latter...
Absence of Replica Symmetry Breaking in a Region of the Phase Diagram of the Ising Spin Glass (2000)
Nishimori, Hidetoshi, Sherrington, David
We prove that the distribution functions of magnetization and spin glass order parameter coincide on the Nishimori line in the phase diagram of the $\pm J$ Ising model in any dimension. This implies...
Exact Solution of the Infinite-Range Quantum Mattis Model (2000)
Sollich, P., Nishimori, Hidetoshi, Coolen, A. C. C., Van Der Sijs, A. J.
We have solved the quantum version of the Mattis model with infinite-range interactions. A variational approach gives the exact solution for the infinite-range system, in spite of the non-commutative...
Error-correcting codes and image restoration with multiple stages of dynamics (2000)
Wong, K. Y. Michael, Nishimori, Hidetoshi
We consider the problems of error-correcting codes and image restoration with multiple stages of dynamics. Information extracted from the former stage can be used selectively to improve the...
Quantum Annealing in the Transverse Ising Model (1998)
Kadowaki, Tadashi, Nishimori, Hidetoshi
We introduce quantum fluctuations into the simulated annealing process of optimization problems, aiming at faster convergence to the optimal state. Quantum fluctuations cause transitions between...
Convergence of simulated annealing by the generalized transition probability (1998)
Nishimori, Hidetoshi, Inoue, Jun-ichi
We prove weak ergodicity of the inhomogeneous Markov process generated by the generalized transition probability of Tsallis and Stariolo under power-law decay of the temperature. We thus have a...
A Simple Perceptron that Learns Non-Monotonic Rules (1997)
. We investigate the generalization ability of a simple perceptron trained in the off-line and on-line supervised modes. Examples are extracted from the teacher who is a non-monotonic perceptron. For...
A Simple Perceptron that Learns Non-Monotonic Rules (1997)
Inoue, Jun-ichi, Nishimori, Hidetoshi, Kabashima, Yoshiyuki
We investigate the generalization ability of a simple perceptron trained in the off-line and on-line supervised modes. Examples are extracted from the teacher who is a non-monotonic perceptron. For...
Generalization ability of a perceptron with non-monotonic transfer function (1997)
Inoue, Jun-ichi, Nishimori, Hidetoshi, Kabashima, Yoshiyuki
We investigate the generalization ability of a perceptron with non-monotonic transfer function of a reversed-wedge type in on-line mode. This network is identical to a parity machine, a multilayer...
High-Temperature Dynamics of Spin Glasses (1997)
Yamana, Michiko, Nishimori, Hidetoshi, Kadowaki, Tadashi, Sherrington, D.
We develop a systematic expansion method of physical quantities for the SK model and the finite-dimensional $\pm J$ model of spin glasses in non-equilibrium states. The dynamical probability...
On-Line AdaTron Learning of Unlearnable Rules (1997)
Inoue, Jun-ichi, Nishimori, Hidetoshi
We study the on-line AdaTron learning of linearly non-separable rules by a simple perceptron. Training examples are provided by a perceptron with a non-monotonic transfer function which reduces to...
On-line learning of non-monotonic rules by simple perceptron (1997)
Inoue, Jun-ichi, Nishimori, Hidetoshi, Kabashima, Yoshiyuki
We study the generalization ability of a simple perceptron which learns unlearnable rules. The rules are presented by a teacher perceptron with a non-monotonic transfer function. The student is...
Quantum Effects in Neural Networks (1996)
Nishimori, Hidetoshi, Nonomura, Yoshihiko
We develop the statistical mechanics of the Hopfield model in a transverse field to investigate how quantum fluctuations affect the macroscopic behavior of neural networks. When the number of...
Exact Ground-State Energy of the Ising Spin Glass on Strips (1996)
Kadowaki, Tadashi, Nonomura, Yoshihiko, Nishimori, Hidetoshi
We propose a new method for exact analytical calculation of the ground-state energy of the Ising spin glass on strips. An outstanding advantage of this method over the numerical transfer matrix...
Dynamical Probability Distribution Function of the SK Model at High Temperatures (1995)
Nishimori, Hidetoshi, Yamana, Michiko
The microscopic probability distribution function of the Sherrington-Kirkpatrick (SK) model of spin glasses is calculated explicitly as a function of time by a high-temperature expansion. The...
Nonomura, Yoshihiko, Nishimori, Hidetoshi
The Hopfield model in a transverse field is investigated in order to clarify how quantum fluctuations affect the macroscopic behavior of neural networks. Using the Trotter decomposition and the...
西森, 秀稔, ニシモリ, ヒデトシ, Nishimori, Hidetoshi
電子情報通信学会基礎・境界ソサイエティ主催企画 若手研究者・学生向けに,最新技術をわかりやすく紹介する講演会...
西森, 秀稔, ニシモリ, ヒデトシ, Nishimori, Hidetoshi
電子情報通信学会基礎・境界ソサイエティ主催企画 若手研究者・学生向けに,最新技術をわかりやすく紹介する講演会...
西森, 秀稔, ニシモリ, ヒデトシ, Nishimori, Hidetoshi
電子情報通信学会基礎・境界ソサイエティ主催企画 若手研究者・学生向けに,最新技術をわかりやすく紹介する講演会...
西森, 秀稔, ニシモリ, ヒデトシ, Nishimori, Hidetoshi
電子情報通信学会基礎・境界ソサイエティ主催企画 若手研究者・学生向けに,最新技術をわかりやすく紹介する講演会...