Jun-ichi Inoue

Publications (7)2.26 Total impact

• Article: STATPHYS-Kolkata VII

  Jayanta Kumar Bhattacharjee, Bikas K Chakrabarti, Jun-Ichi Inoue, Parongama Sen
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  ABSTRACT: In the past two decades, a series of international conferences on Statistical Physics, going by the name Statphys Kolkata, have been organized in Kolkata (previously Calcutta) at roughly three-year intervals, the first one being held in 1992–93. The seventh of this series, Statphys Kolkata VII (http://www.saha.ac.in/cmp/stat.vii/index.php) was held from 26–30 November 2010. This meeting was organized as part of the Silver Jubilee Celebration of the Satyendra Nath Bose National Centre for Basic Sciences, Kolkata, in collaboration with the Saha Institute of Nuclear Physics, Kolkata. In Statphys Kolkata VII, a few topics of current interest such as Collective behavior and emergent phenomena, Systems far from equilibrium, Soft matter, and Quantum critical phenomena were given special emphasis, while various other issues of Statistical Physics were also addressed. We were happy to note that the conference attracted a large number of participants, and the talk and poster sessions generated a lot of discussions, arguments and collaborations. The articles appearing in this proceedings are based on the invited talks and selected poster presentations. We would like to thank the Journal of Physics Conference Series, IOP, for publishing the proceedings of the conference, and the referees for their prompt and active support. The proceedings of the earlier Statphys Kolkata conferences have appeared in Physica A, vol 384 (2007); Physica A, vol 346 (2005); Physica A, vol 318 (2003); Physica A, vol 270 (1999); Physica A, vol 224 (1996); and Physica A, vol 186 (1992). We would like to take this opportunity to thank all the members of the organizing committee (especially Dr Anjan Kumar Chandra for extensive all-round help), and acknowledge the Centre for Applied Mathematics and Computational Science (CAMCS, Saha Institute of Nuclear Physics, Kolkata) and Satyendra Nath Bose National Centre for Basic Sciences, Kolkata, for their financial support. Jayanta Kumar Bhattacharjee, Bikas K Chakrabarti, Jun-Ichi Inoue and Parongama SenConvenors and Editors of the proceedings
  Journal of Physics Conference Series 05/2011; 297(1):011001.
• Source

  Available from: arxiv.org

  Article: Quantum phase transition in a disordered long-range transverse Ising antiferromagnet.

  Anjan Kumar Chandra, Jun-ichi Inoue, Bikas K Chakrabarti
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  ABSTRACT: We consider a long-range Ising antiferromagnet put in a transverse field (LRTIAF) with disorder. We have obtained the phase diagrams for both the classical and quantum cases. For the pure case applying quantum Monte Carlo method, we study the variation in order parameter (spin correlation in the Trotter direction), susceptibility, and average energy of the system for various values of the transverse field at different temperatures. The antiferromagnetic order is seen to get immediately broken as soon as the thermal or quantum fluctuations are added. We discuss generally the phase diagram for the same LRTIAF model with perturbative Sherrington-Kirkpatrick-type disorder. We find that while the antiferromagnetic order is immediately broken as one adds an infinitesimal transverse field or thermal fluctuation to the pure LRTIAF system, an infinitesimal SK spin-glass disorder is enough to induce a stable glass order in the LRTIAF. This glass order eventually gets destroyed as the thermal or quantum fluctuations are increased beyond their threshold values and the transition to paramagnetic phase occurs. Analytical studies for the phase transitions are discussed in details in each case. These transitions have been confirmed by applying classical and quantum Monte Carlo methods. We show here that the disordered LRTIAF has a surrogate incubation property of the SK spin glass phase.
  Physical Review E 02/2010; 81(2 Pt 1):021101. · 2.26 Impact Factor
• Source

  Available from: ArXiv

  Article: A Novel Quantum Transition in a Fully Frustrated Transverse Ising Antiferromagnet

  Anjan Kumar Chandra, Jun-ichi Inoue, Bikas K. Chakrabarti
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  ABSTRACT: We consider a long-range Ising antiferromagnet (LRIAF) put in a transverse field. Applying quantum Monte Carlo method, we study the variation of order parameter (spin correlation in Trotter time direction), susceptibility and average energy of the system for various values of the transverse field at different temperatures. The antiferromagnetic order is seen to get immediately broken as soon as the thermal or quantum fluctuations are added. We also discuss the phase diagram for the Sherrington-Kirkpatrick (SK) model with the same LRIAF bias, also in presence of a transverse field. We find that while the antiferromagnetic order is immediately broken as one adds an infinitesimal transverse field or thermal fluctuation to the system, an infinitesimal SK spin glass disorder is enough to induce a stable glass order in the antiferromagnet. This glass order eventually gets destroyed as the thermal or quantum fluctuations increased beyond their threshold values and the transition to para phase occurs. Indications of this novel phase transition are discussed. Because of the presence of full frustration, this surrogate property of the LRIAF for incubation of stable spin glass phase in it (induced by addition of a small disorder) should enable eventually the study of classical and quantum spin glass phases by using some perturbation theory with respect to the disorder. Comment: 9 pages, 5 figures
  05/2008;
• Source

  Available from: arxiv.org

  Article: A solvable quantum antiferromagnet model

  Bikas K. Chakrabarti, Jun-ichi Inoue
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  ABSTRACT: We introduce a quantum antiferromagnet model, having exactly soluble thermodynamic properties. It is an infinite range antiferromagnetic Ising model put in a transverse field. The free energy gives the ground state energy in the zero temperature limit and it also gives the low temperature behaviour of the specific heat, the exponential variation of which gives the precise gap magnitude in the excitation spectrum of the system. The detailed behaviour of the (random sublattice) staggard magnetisation and susceptibilities are obtained and studied near the N\'eel temperature and the zero temperature quantum critical point.
  09/2005;
• Source

  Available from: hokudai.ac.jp

  Article: Similarity in transitions of two distinct number networks

  Anjan Kumar Chandra, Jun-ichi Inoue
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  ABSTRACT: The main objective of our study is to disclose if any network structure is hidden among the pairs of numbers obtained by splitting the consecutive integers. By adopting some preferred rule in placing the links among the pairs obtained, we have a transition from a regular to a random one through a small world one. This type of transition is also similar to the network of primes obtained by splitting the consecutive integers which indicates some general feature in both kinds of networks. We also obtained both some numerical and analytical explanations, that support the transition and also the point of transition.
• Source

  Available from: Arnab Das

  Article: Analysis of a long-range random field quantum antiferromagnetic Ising model

  Bikas K. Chakrabarti, Arnab Das, Jun-ichi Inoue
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  ABSTRACT: We introduce a solvable quantum antiferromagnetic model. The model, with Ising spins in a transverse field, has infinite range antiferromagnetic interactions and random fields on each site following an arbitrary distribution. As is well-known, frustration in the random field Ising model gives rise to a many valley structure in the spin-configuration space. In addition, the antiferromagnetism also induces a regular frustration even for the ground state. In this paper, we investigate analytically the critical phenomena in the model, having both randomness and frustration and we report some analytical results for it.
• Source

  Available from: arxiv.org

  Article: Competition between ferro-retrieval and anti-ferro orders in a Hopfield-like network model for plant intelligence

  Jun-ichi Inoue, Bikas K. Chakrabarti
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  ABSTRACT: We introduce a simple cellular-network model to explain the capacity of the plants as memory devices. Following earlier observations (Bose (The Nervous Mechanism of Plants, Longmans, London, 1923) and others), we regard the plant as a network in which each of the elements (plant cells) are connected via negative (inhibitory) interactions. To investigate the performance of the network, we construct a model following that of Hopfield, whose energy function possesses both Hebbian spin glass and anti-ferromagnetic terms. With the assistance of the replica method, we find that the memory state of the network decreases enormously due to the effect of the anti-ferromagnetic order induced by the inhibitory connections. We conclude that the ability of the plant as a memory device is rather weak.
  Physica A: Statistical Mechanics and its Applications.