#### 09 Sep 2018 日本物理学会　2018年秋季大会にて講演。

• 講演(9aM302-1) "エントロピーを用いた(1+1)次元有向浸透現象の動的過程の特徴付け"、9月9日午前9時、領域11：非平衡揺らぎ
• ポスター講演(12aPS-96) "テンソルネットワークによる有向浸透現象の数値的研究"、9月12日午前10時、領域11：ポスターセッション（発表者：鉈落佳奈）

#### 01 Aug 2018 物性研短期研究会「量子情報・物性の新潮流」にて講演。

タイトル: "エンタングルメント分岐とその活用"
• 日時: 2018年8月1日午後2時半
• 会議名: 物性研短期研究会「量子情報・物性の新潮流」
• 会議日程: 2018年8月1日から2018年8月3日（3日間）
• 開催場所: 東京大学柏キャンパス　東京大学物性研究所　大講義室（千葉県柏市）
• URL: http://www.qi.t.u-tokyo.ac.jp/workshop/NQuIC2018/index.html

#### 19 Jul 2018 第3回CDMSI(ポスト「京」重点課題7)研究会にてポスター発表。

• 講演："1次元確率過程のテンソルネットワークシミュレーション"
• 日程：２０１８年７月１９日(木) ～ ２０日(金)
• 場所：東京大学　小柴ホール／本郷キャンパス
• 研究会Webページ：https://ccms.issp.u-tokyo.ac.jp/event/246

#### 02 Apr 2018 物性研究所スパコン共同利用・CCMS合同研究会「計算物質科学の今と未来」にてポスター発表。

• 講演："有向浸透臨界現象におけるエントロピーから見たユニバーサリティクラス"
• 日程：４月２日(月) ～ ３日(火)
• 場所：東京大学物性研究所 6階 大講義室
• 研究会Webページ：http://ccms.issp.u-tokyo.ac.jp/events/eventsfolder/keisan18

#### 24 Mar 2018 日本物理学会　第73回年次大会にて講演。

• 講演(24pK604-6) "テンソルネットワークを用いた1次元非平衡モデルの時間発展シミュレーション"、3月24日午後、領域11：統計力学基礎論2・非平衡揺らぎ

#### 08 Mar 2018 Talk "Entanglement Branching Operator and its Applications", Session S34: Precision Many Body Physics IV on APS March Meeting 2018 (Los Angeles, California, USA)

March 5–9, 2018, Los Angeles, California, USA.

Reference: Physical Review B 97 (2018) 045124.

#### 16 Jan 2018 Paper "Entanglement branching operator" is published in Physical Review B.

REFERENCE Physical Review B 97 (2018) 045124
DOI 10.1103/PhysRevB.97.045124
ABSTRACT We introduce an entanglement branching operator to split a composite entanglement flow in a tensor network which is a promising theoretical tool for many-body systems. We can optimize an entanglement branching operator by solving a minimization problem based on squeezing operators. The entanglement branching is a new useful operation to manipulate a tensor network. For example, finding a particular entanglement structure by an entanglement branching operator, we can improve a higher-order tensor renormalization group method to catch a proper renormalization flow in a tensor network space. This new method yields a new type of tensor network states. The second example is a many-body decomposition of a tensor by using an entanglement branching operator. We can use it for a perfect disentangling among tensors. Applying a many-body decomposition recursively, we conceptually derive projected entangled pair states from quantum states that satisfy the area law of entanglement entropy.

#### 04 Jan 2018 Wei-Lin Tu visits our laboratory until Mar. 5, 2018.

Wei-Lin is a student in a doctoral course of National Taiwan University. His stay is financially supported by Japan-Taiwan Exchange Association.

#### 20 Nov 2017 Poster presentation on International Symposium on Fluctuation and Structure out of Equilibrium 2017 (SFS2017) (Sendai, Japan)

International Symposium on Fluctuation and Structure out of Equilibrium 2017 (SFS2017)
• Date of poster presentation: 14:50 ~ 16:50, 20th Nov. 2017.
• Conference: International Symposium on Fluctuation and Structure out of Equilibrium 2017
• Conference dates: From 20th Nov. 2017 to 23th Nov. 2017.
• Venue: Sendai International Center, Sendai, Japan.
• URL：http://sfs-dynamics.jp/sfs2017/

#### 06 Nov 2017 Talk "Entanglement branching operator" in Novel Quantum States in Condensed Matter 2017 (YITP, Kyoto, Japan)

Title: "Entanglement branching operator" (invited)
• Date of presentation: 14:00 ~ 15:00, 6th Nov. 2017.
• Conference: Novel Quantum States in Condensed Matter 2017
• Conference dates: From 23th Oct. 2017 to 24th Nov. 2017.
• Venue: Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto, Japan.
• URL：http://www2.yukawa.kyoto-u.ac.jp/~nqs2017.ws/index.php
Preprint
arXiv:1710.01830
Abstract
We introduce an entanglement branching operator to split a composite entanglement flow in a tensor network which is a promising theoretical tool for many-body systems. We can optimize an entanglement branching operator by solving a minimization problem based on squeezing operators. The entanglement branching is a new useful operation to manipulate a tensor network. For example, finding a particular entanglement structure by an entanglement branching operator, we can improve a higher-order tensor renormalization group method to catch a proper renormalization flow in a tensor network space. This new method yields a new type of tensor network states. The second example is a many-body decomposition of a tensor by using an entanglement branching operator. We can use it for a perfect disentangling among tensors. Applying a many-body decomposition recursively, we conceptually derive projected entangled pair states from quantum states that satisfy the area law of entanglement entropy.

#### 05 Oct 2017 Paper "Entanglement branching operator" is submitted.

Preprint
arXiv:1710.01830
Author
Abstract
We introduce an entanglement branching operator to split a composite entanglement flow in a tensor network which is a promising theoretical tool for many-body systems. We can optimize an entanglement branching operator by solving a minimization problem based on squeezing operators. The entanglement branching is a new useful operation to manipulate a tensor network. For example, finding a particular entanglement structure by an entanglement branching operator, we can improve a higher-order tensor renormalization group method to catch a proper renormalization flow in a tensor network space. This new method yields a new type of tensor network states. The second example is a many-body decomposition of a tensor by using an entanglement branching operator. We can use it for a perfect disentangling among tensors. Applying a many-body decomposition recursively, we conceptually derive projected entangled pair states from quantum states that satisfy the area law of entanglement entropy.
9 pages, 11 figures

#### 24 Sep 2017 日本物理学会　２０１７年秋季大会にて講演。

• 講演 "エンタングルメント分岐を用いたテンソル繰り込み群", 24aJ25-10

#### 11 Jul 2017 第2回CDMSI(ポスト「京」重点課題7)研究会にてポスター発表。

• 講演："エンタングルメント分岐を用いたテンソル繰り込み群"
• 日程：７月１１日(火) ～ １２日(水)
• 場所：東京大学　小柴ホール／本郷キャンパス
• 研究会Webページ：http://post-k.cms-initiative.jp/events/sympo20170711

#### 18 Mar 2017 日本物理学会　第72回年次大会にてシンポジウム講演。

• 講演 "繰り込み群とテンソルネットワーク" 18pB11-3、
領域11、領域3、素粒子論領域合同シンポジウム
「テンソルネットワーク法とその可能性」
• （共同研究者 伊井海生 発表）講演 "非平衡系のための数値的手法の開発" 19pK-PS-50
• （共同研究者 佐藤龍己 発表）講演 "有向浸透現象の数値的手法の開発" 19pS-PS-27
• （共同研究者 正木晶子 発表）講演 "並列化量子モンテカルロ法によるrelevant fieldを含む有限サイズスケーリング" 20aB11-7

#### 05 Feb 2017 Workshop in the Centro de Ciencias de Benasque Pedro Pascual, Benasque, Spain : "Entanglement in Strongly Correlated Systems"

From 5 Feb. 2017 to 18 Feb. 2017, Workshop "Entanglement in Strongly Correlated Systems" , the Centro de Ciencias de Benasque Pedro Pascual, Benasque, Spain.

#### 14 Dec 2016 Talk "General Entanglement Branching in a Tensor Network" in Fourth Workshop on Tensor Network States: Algorithms and Applications (NCTS, Hsinchu, Taiwan)

• Title: "General Entanglement Branching in a Tensor Network" (invited)
• Date of presentation: 14th Dec. 2016.
• Conference: Fourth Workshop on Tensor Network States: Algorithms and Applications
• Conference dates: From 12th Dec. 2016 to 15th Dec. 2016.
• Venue: National Center for Theoretical Sciences, Hsinchu, Taiwan
• URL：http://www.phys.cts.nthu.edu.tw/actnews/index.php?Sn=318

#### 13 Sep 2016 日本物理学会　2016年秋季大会にて講演。

9月13日から9月16日、

• 講演 "SU(N)一般化ハイゼンベルグモデルの量子相転移：Conformal bootstrap法の結果との比較、SO(5)対称性の検証" 13aAF-9

ポスト「京」萌芽的課題

キックオフミーティングに参加。

#### 10 Aug 2016 京都大学オープンキャンパス2016：研究室紹介

2016年度の京都大学オープンキャンパスで、研究室紹介を2回行う。テーマは、 "シミュレーションの最先端＋スパコン「京」"。主に、スパコン「京」で行っ ている大規模シミュレーションを紹介する予定。

#### 27 Jun 2016 International Workshop on Tensor Networks and Quantum Many-Body Problems (TNQMP2016)に参加。

• 日程：２０１６年６月２７日（月） ～ ２０１６年７月１５日（金）（３週間）
• 開催場所：東京大学物性研究所 (〒277−8581 柏市柏の葉5−1−5)
• URL：http://www.issp.u-tokyo.ac.jp/public/tnqmp2016/

#### 19 Mar 2016 日本物理学会　第71回年次大会にて講演。

3月19日から3月22日、

• 講演 "分岐とテンソルネットワーク" 20pBT-5

#### 16 Mar 2016 Quantum Computation and Machine Learning Seminar Series（早稲田大学）にて講演。

2016年3月16日(水) 15:00~、早稲田大学早稲田キャンパス３号館203号室、
Quantum Computation and Machine Learning Seminar Seriesにて講演。

（後半の内容は、新潟大学理学部 奥西巧一さんとの共同研究の成果です）

[1] K. Okunishi and K. Harada, Phys. Rev. B 89, 134422 (2014).
[2] K. Harada and K. Okunishi, unpublished (2016).

#### 29 Jan 2016 スパコン「京」がひらく科学と社会　シンポジウム「スーパーコンピュータの今とこれから」にて講演。

2016年1月29日（金）、 講演　”シミュレーションで探る量子の世界：絶対零度での秩序と臨界現象”、 スパコン「京」がひらく社会と科学　シンポジウム「スーパーコンピュータの今とこれから」、 よみうり大手町ホール（東京）。

#### 25 Jan 2016 参加登録開始：International Workshop on Tensor Networks and Quantum Many-Body Problems (TNQMP2016)

• 日程：２０１６年６月２７日（月） ～ ２０１６年７月１５日（金）（３週間）
• 開催場所：東京大学物性研究所 (〒277−8581 柏市柏の葉5−1−5)
• URL（参加登録）：http://www.issp.u-tokyo.ac.jp/public/tnqmp2016/

#### 11 Jan 2016 (The 75th Okazaki Conference) Tensor Network States: Algorithms and Applications 2016に参加。

• 日程：１月１１日(月) ～ １４日(木)
• 場所：分子科学研究所　岡崎カンファレンスホール
• 研究会Webページ：http://qm.ims.ac.jp/tnsaa2016/

#### 22 Oct 2015 理化学研究所 計算科学研究機構 広報誌「計算科学の世界」No.11に、インタビュー記事掲載。

Web 理化学研究所 計算科学研究機構 広報誌「計算科学の世界」
PDF 理化学研究所 計算科学研究機構 広報誌「計算科学の世界」No.11

#### 05 Oct 2015 Paper "SU(N) Heisenberg model with multicolumn representations" is published in Physical Review B.

REFERENCE Physical Review B 92 (2015) 134404
DOI 10.1103/PhysRevB.92.134404
AUTHOR Tsuyoshi Okubo, Kenji Harada, Jie Lou, and Naoki Kaishima
ABSTRACT The SU(N) symmetric antiferromagnetic Heisenberg model with multicolumn representations on the two- dimensional square lattice is investigated by quantum Monte Carlo simulations. For the representation of a Young diagram with two columns, we confirm that a valence-bond solid (VBS) order appears as soon as the Néel order disappears at N = 10, indicating no intermediate phase. In the case of the representation with three columns, there is no evidence for either the Néel or the VBS ordering for N >= 15. This is actually consistent with the large-N theory, which predicts that the VBS state immediately follows the Néel state, because the expected spontaneous order is too weak to be detected.

9月16日から9月19日、

#### 06 Jul 2015 Paper "Kernel methods for corrections to scaling" is published in Physical Review E.

REFERENCE Physical Review E 92 (2015) 012106
DOI 10.1103/PhysRevE.92.012106
ABSTRACT Scaling analysis, in which one infers scaling exponents and a scaling function in a scaling law from given data, is a powerful tool for determining universal properties of critical phenomena in many fields of science. However, there are corrections to scaling in many cases, and then the inference problem becomes ill-posed by an uncontrollable irrelevant scaling variable. We propose a new kernel method based on Gaussian process regression to fix this problem generally. We test the performance of the new kernel method for some example cases. In all cases, when the precision of the example data increases, inference results of the new kernel method correctly converge. Because there is no limitation in the new kernel method for the scaling function even with corrections to scaling, unlike in the conventional method, the new kernel method can be widely applied to real data in critical phenomena.
NOTE The reference code of this new method is prepared at http://kenjiharada.github.io/BSA/

#### 25 May 2015 第32回量子情報技術研究会(QIT32)にてチュートリアル講演。

5月25日から5月26日、 チュートリアル講演 "量子フラストレート磁性体のテンソルネットワークを用いた数値的研究"、 第32回量子情報技術研究会 (QIT32)、大阪大学。

#### 22 Apr 2015 Bayesian Scaling Analysis (BSA) ツールキットのバグを訂正。

BSAツールキットは臨界現象のスケーリング解析を行う新手法の参照コードです。ベイズ推定の力を用いて、自動的に臨界点や臨界指数を求めることができます。スケーリング補正を考慮した場合（オプション"-f 1"）のスケーリング関数の推定結果の出力部分にあるバグを訂正しました。このバグはパラメータの推定結果には影響はありません。

#### 21 Apr 2015 Paper "SU(N) Heisenberg model with multi-column representations" is submitted.

PREPRINT arXiv:1504.05332
AUTHOR Tsuyoshi Okubo, Kenji Harada, Jie Lou, Naoki Kaishima
ABSTRACT The SU(N) symmetric antiferromagnetic Heisenberg model with multi-column representations on the two-dimensional square lattice is investigated by quantum Monte Carlo simulations. For the representation of Young diagram with two columns, we confirm that a valence-bond solid order appears as soon as the N'eel order disappears at N = 10 indicating no intermediate phase. In the case of the representation with three columns, there is no evidence for both of the N'eel and the valence-bond solid ordering for N >= 15. This is actually consistent with the large-N theory, which predicts that the VBS state immediately follows the N'eel state, because the expected spontaneous order is too weak to be detected.

#### 21 Mar 2015 日本物理学会　第70回年次大会にてシンポジウム講演。

3月21日から3月24日、

• シンポジウム講演 "二次元SU(N)ハイゼンベルグモデルにおける脱閉じ込め量子臨界現象" 22aAL-4
• （共同研究者 吉田天平）講演 "ダイマーモット絶縁体における電荷揺らぎの解析" 24aAB-9

#### 16 Mar 2015 Paper "Thermal phase transition of generalized Heisenberg models for SU(N) spins on square and honeycomb lattices" is published in Physical Review B.

REFERENCE Physical Review B 91 (2015) 094414
DOI 10.1103/PhysRevB.91.094414
AUTHOR Takafumi Suzuki, Kenji Harada, Haruhiko Matsuo, Synge Todo, and Naoki Kaishima
ABSTRACT We investigate thermal phase transitions to a valence-bond solid phase in SU(N) Heisenberg models with four- or six-body interactions on a square or honeycomb lattice, respectively. In both cases, a thermal phase transition occurs that is accompanied by rotational symmetry breaking of the lattice. We perform quantum Monte Carlo calculations in order to clarify the critical properties of the models. The estimated critical exponents indicate that the universality classes of the square- and honeycomb-lattice cases are identical to those of the classical XY model with a Z4 symmetry-breaking field and the three-state Potts model, respectively. In the square-lattice case, the thermal exponent, ν, monotonically increases as the system approaches the quantum critical point, while the values of the critical exponents, η and γ/ν, remain constant. From a finite-size scaling analysis, we find that the system exhibits weak universality, because the Z4 symmetry-breaking field is always marginal. In contrast, ν in the honeycomb-lattice case exhibits a constant value, even in the vicinity of the quantum critical point, because the Z3 field remains relevant in the SU(3) and SU(4) cases.

#### 18 Feb 2015 Talk "Quantum Monte Carlo Study of Quantum Criticality on SO(N) Bilinear-biquadratic Chains" in the International Workshop on New Frontier of Numerical Methods for Many-Body Correlations ― Methodologies and Algorithms for Fermion Many-Body Problems.

Title: ''Quantum Monte Carlo study of Quantum Criticality on SO(N) Bilinear-biquadratic Chains''
Date: Feb. 18, 2015
Conference: From Feb. 18, 2015 to Feb. 21, 2015, International Workshop on New Frontier of Numerical Methods for Many-Body Correlations ― Methodologies and Algorithms for Fermion Many-Body Problems , Hongo Campus, The University of Tokyo, Japan.

#### 07 Jan 2015 Invited talk "Quantum Monte Carlo study of Quantum Criticality on SO(N) Bilinear Biquadratic Chains" in the 9th International Conference on Computational Physics (ICCP9).

Title: ''Quantum Monte Carlo study of Quantum Criticality on SO(N) Bilinear Biquadratic Chains''
Date: Jan. 9, 2015
Conference: From Jan. 7, 2015 to Jan. 11, 2015, the 9th International Conference on Computational Physics (ICCP9) , National University of Singapore, Singapore.

#### 26 Dec 2014 理化学研究所セミナーにて講演：「MERAテンソルネットワークを用いた量子多体系の計算手法」。

タイトル:「MERAテンソルネットワークを用いた量子多体系の計算手法」

#### 15 Dec 2014 YITP短期研究会 "量子多体系研究の新しい潮流 --テンソルネットワーク・繰り込み群・エンタングルメント--"に参加。

YITP短期研究会 "量子多体系研究の新しい潮流 --テンソルネットワーク・繰り込み群・エンタングルメント--"に参加。

#### 09 Dec 2014 第５回 CMSI 研究会にてポスター講演"カーネル法を用いた臨界現象の有限サイズスケーリング法とその応用"。

ポスター講演： 2014年12月9日（火）"カーネル法を用いた臨界現象の有限サイズスケーリング法とその応用"

#### 25 Nov 2014 Talk "MERA tensor network and its application on quantum frustrated magnets" in the 10sor network workshop --- Field 2x5 joint workshop on new algorithms for quantum manybody problems ---.

Conference: 10sor network workshop --- Field 2x5 joint workshop on new algorithms for quantum manybody problems ---
Date: November 25, 2014, Tuedsay
Venue: Kashiwa Future Center, Kashiwa, Chiba, Japan
Title: "MERA tensor network and its application on quantum frustrated magnets"

#### 17 Nov 2014 Talk "Possibility of Deconfined Criticality in SU(N) Heisenberg Models at Small N" in the YITP long-term Workshop "Novel Quantum States in Condensed Matter 2014" (NQS2014).

From Nov. 4, 2014 to Dec. 2, 2014, the YITP long-term Workshop "Novel Quantum States in Condensed Matter 2014" (NQS2014) , YITP, Kyoto university, Kyoto, Japan.

#### 13 Nov 2014 物性研究所計算物質科学研究センター 第4回シンポジウム・物性研スーパーコンピュータ共同利用報告会にてポスター講演 "Kernel Method for Scaling Analysis of Critical Phenomena and its Implementation"。

ポスター講演： 2014年11月13日（木）"Kernel Method for Scaling Analysis of Critical Phenomena and its Implementation"

#### 20 Oct 2014 Poster "Tensor network calculation on large-scale parallel computer" in the CMSI International Workshop 2014: Tensor Network Algorithms in Materials Science.

From 20 Oct. 2014 to 22 Oct. 2014, the CMSI International Workshop 2014: Tensor Network Algorithms in Materials Science , RIKEN Advanced Institute for Computational Science 6F auditorium 7-1-26, Port Island South, Kobe, 650-0047, Japan.

#### 15 Oct 2014 有限サイズスケーリングを行う新アプリケーションを公開。

ツールキット BSAに新アプリケーション"new_bfss"を追加。臨界現象の有限サイズスケーリングにスケーリング補正を考慮した解析も行う新手法の参照コードです。カーネル法を用いて簡単に臨界点や臨界指数を求めることができます。

#### 14 Oct 2014 Paper "Kernel Methods for Corrections to Scaling" is submitted.

PREPRINT arXiv:1410.3622
ABSTRACT Scaling analysis, in which one infers scaling exponents and a scaling function in a scaling law from given data, is a powerful tool for determining universal properties of critical phenomena in many fields of science. However, there are corrections to scaling in many cases, and then the inference problem becomes ill-posed by an uncontrollable irrelevant scaling variable. We propose a new kernel method based on Gaussian process regression to fix this problem generally. We test the performance of the new kernel method for some example cases. In all cases, when the precision of the example data increases, inference results of the new kernel method correctly converge. Because there is no limitation in the new kernel method for the scaling function even with corrections to scaling, unlike in the conventional method, the new kernel method can be widely applied to real data in critical phenomena.

#### 07 Sep 2014 日本物理学会２０１４年秋季大会にて講演。

９月７日から９月１０日、

• 講演 "有限サイズスケーリング補正のカーネル法" 10aAY-6
• 講演 （共同研究者）"一般化Jordan-Wigner変換とZ2xZ2対称性" 10pAQ-4
• 講演 "SO(N) bilinear-biquadratic スピン鎖の量子臨界性とストリング秩序の数値的研究" 10pAQ-5

#### 17 Aug 2014 CMSI 第１部会「新物質・新量子相の基礎科学」 夏の学校 2014に参加。

• 主催：CMSI第1部会
• 日程：8月18日(月) ～ 22日(金)
• 場所：滋賀県高島市安曇川町近江白浜

#### 27 Jun 2014 Paper "Tensor Network Studies of Quantum Frustrated Magnets" is published in Proceedings of the International Conference on Strongly Correlated Electron Systems (SCES2013).

REFERENCE JPS Conf. Proc. 3 , 014031 (2014) [7 pages]
Proceedings of the International Conference on Strongly Correlated Electron Systems (SCES2013)
DOI 10.7566/JPSCP.3.014031
ABSTRACT We will introduce tensor network states in the variational calculation of ground states for quantum frustrated magnets. In particular, we will report the performance of MERA tensor network for an S = 1/2 antiferromagnetic Heisenberg model on a spatially anisotropic triangular lattice, which is an effective model of Mott insulators on a triangular layer of organic charge transfer salts.

#### 26 Jun 2014 Talk "Symmetry-protected topological order and negative-sign problem for SO(N) bilinear-biquadratic chains" (Poster) in the ISSP International Workshop, "New Horizon of Strongly Correlated Physics" (NHSCP2014).

From 25 to 27 June 2014, the ISSP International Workshop, "New Horizon of Strongly Correlated Physics" (NHSCP2014) at the Institute for Solid State Physics (ISSP), The University of Tokyo.

#### 24 Apr 2014 Paper "Symmetry-protected topological order and negative-sign problem for SO(N) bilinear-biquadratic chains" is published in Physical Review B.

REFERENCE Physical Review B 89 (2014) 134422
DOI 10.1103/PhysRevB.89.134422
PREPRINT arXiv:1312.2643
AUTHOR Kouichi Okunishi and Kenji Harada
ABSTRACT Using a generalized Jordan-Wigner transformation combined with the defining representation of the SO(N) spin, we map the SO(N) bilinear-biquadratic(BLBQ) spin chain into the N-color bosonic particle model. We find that, when the Jordan-Wigner transformation disentangles the symmetry-protected topological entanglement, this bosonic model becomes negative-sign free in the context of quantum Monte-Carlo simulation. For the SO(3) case, moreover, Kennedy-Tasaki's transformation for the S=1 BLBQ chain, which is also a topological disentangler, derives the same bosonic model through the dimer-R bases. We present temperature dependence of energy, entropy and string order parameter for the SO(N=3, 4, 5) BLBQ chains by the world-line Monte-Carlo simulation for the N-color bosonic particle model.

#### 10 Apr 2014 Paper "Parallelized quantum Monte Carlo algorithm with non-local worm updates" is published in Physical Review Letters.

REFERENCE Physical Review Letters 112 (2014) 140603
DOI 10.1103/PhysRevLett.112.140603
PREPRINT arXiv:1307.0328
AUTHOR Akiko Masaki-Kato, Takafumi Suzuki, Kenji Harada, Synge Todo, Naoki Kaishima
ABSTRACT Based on the worm algorithm in the path-integral representation, we propose a general quantum Monte Carlo algorithm suitable for parallelizing on a distributed-memory computer by domain decomposition. Of particular importance is its application to large lattice systems of bosons and spins. A large number of worms are introduced and its population is controlled by a fictitious transverse field. For a benchmark, we study the size-dependence of the Bose-condensation order parameter of the hardcore Bose-Hubbard model with $L\times L\times \beta t = 10240\times 10240\times 16$, using 3200 computing cores, which shows good parallelization efficiency.

#### 27 Mar 2014 日本物理学会第６９回年次大会にて講演。

３月２７日から３月３０日、

• 講演 "臨界現象に対する有意でない変数を考慮したベイズ流スケーリング解析手法" 27pAK-9
• 講演（共同研究者）"2次元 SU(N) J-Qモデルにおける脱閉じ込め転移と二つの長さスケール" 28pAK-14
• 講演（共同研究者）"正方格子、蜂の巣格子上一般化SU(N)Heisenberg模型の有限温度転移" 28pAK-15

#### 06 Mar 2014 Talk "Possibility of Deconfined Criticality in SU(N) Heisenberg Models at Small N" S27.00013 in APS March Meeting 2014, Denver, Colorado, USA.

From 3 March 2014 to 7 March 2014,

• Talk (Collaborator) "Parallelized Multi-Worm Algorithm for Large Scale Quantum Monte-Carlo simulations" C1.00284
• Talk (Collaborator) "Thermal phase transitions to valence-bond-solid states in the two dimensional SU(N) Heisenberg models" F7.00010
• Talk (Representative) "Possibility of Deconfined Criticality in SU(N) Heisenberg Models at Small N" S27.00013
APS March Meeting 2014, Denver, Colorado, USA.

#### 13 Feb 2014 物質科学シミュレーションのポータルサイト"MateriApps"にて、ツールキット BSAを紹介。

ツールキット BSAは臨界現象のスケーリング解析を行う新手法の参照コードです。ベイズ推定の力を用いて、自動的に臨界点や臨界指数を求めることができます。このツールキットBSAが、物質科学シミュレーションのポータルサイトMateriAppsにて紹介されました。

#### 13 Dec 2013 Paper "Possibility of Deconfined Criticality in SU(N) Heisenberg Models at Small N" is published in Physical Review B: Rapid Communications.

REFERENCE Physical Review B 88 (2013) 220408(R)
DOI 10.1103/PhysRevB.88.220408
PREPRINT arXiv:1307.0501v2
AUTHOR Kenji Harada, Takafumi Suzuki, Tsuyoshi Okubo, Haruhiko Matsuo, Jie Lou, Hiroshi Watanabe, Synge Todo, and Naoki Kaishima
ABSTRACT To examine the validity of the scenario of the deconfined critical phenomena, we carry out a quantum Monte Carlo simulation for the SU($N$) generalization of the Heisenberg model with four-body and six-body interactions. The quantum phase transition between the SU($N$) N\'eel and valence-bond solid phases is characterized for $N=2,3,$ and $4$ on the square and honeycomb lattices. While finite-size scaling analysis works well up to the maximum lattice size ($L=256$) and indicates the continuous nature of the phase transition, a clear systematic change towards the first-order transition is observed in the estimates of the critical exponent $y \equiv 1/\nu$ as the system size increases. We also confirm the relevance of a squared valence-bond solid field $\Psi^2$ for the SU(3) model.

#### 11 Dec 2013 講演 "SU(N)ハイゼンベルクモデルで脱閉じ込め転移はあるのか？"、 物性研スパコン共同利用・CMSI 合同研究会（第４回 CMSI 研究会）。

１２月１０日から１２月１３日、 物性研スパコン共同利用・CMSI 合同研究会（第４回 CMSI 研究会）、東京大学物性研究所（柏キャンパス）。

#### 10 Dec 2013 Paper "Symmetry-protected topological order and negative-sign problem for SO(N) bilinear-biquadratic chains" is submitted.

PREPRINT arXiv:1312.2643
AUTHOR Kouichi Okunishi and Kenji Harada
ABSTRACT Using a generalized Jordan-Wigner transformation combined with the defining representation of the SO(N) spin, we map the SO(N) bilinear-biquadratic(BLBQ) spin chain into the N-color bosonic particle model. We find that, when the Jordan-Wigner transformation disentangles the symmetry-protected topological entanglement, this bosonic model becomes negative-sign free in the context of quantum Monte-Carlo simulation. For the SO(3) case, moreover, Kennedy-Tasaki's transformation for the S=1 BLBQ chain, which is also a topological disentangler, derives the same bosonic model through the dimer-R bases. We present temperature dependence of energy, entropy and string order parameter for the SO(N=3, 4, 5) BLBQ chains by the world-line Monte-Carlo simulation for the N-color bosonic particle model.

#### 04 Dec 2013 Talk "Deconfined quantum criticality in SU(N) Heisenberg models: Finite size scaling analysis based on Bayesian inference" in Taipei Tensor Network Workshop 2013.

From 2 Dec. 2013 to 5 Dec. 2013, Taipei Tensor Network Workshop 2013 , National Taiwan University, Taipei, Taiwan.

#### 21 Oct 2013 CMSI International Symposium 2013: "Extending the power of computational materials sciences with K-computer".

From 21 Oct. 2013 to 22 Oct. 2013,
CMSI International Symposium 2013: "Extending the power of computational materials sciences with K-computer" , Ito International Research Center in the University of Tokyo, Hongo Campus in Tokyo, Japan.

#### 16 Oct 2013 Satellite Meeting 2013 in Kobe: "CMSI Kobe International Workshop 2013: Recent Progress in Tensor Network Algorithms".

From 16 Oct. 2013 to 18 Oct. 2013, Satellite Meeting 2013 in Kobe: "CMSI Kobe International Workshop 2013: Recent Progress in Tensor Network Algorithms" , RIKEN Advanced Institute for Computational Science, Kobe, Japan.

#### 25 Sep 2013 日本物理学会２０１３年秋季大会にて講演。

９月２５日から９月２８日、

• 講演 "2次元 SU(N) J-Qモデルを用いた脱閉じ込め臨界現象の数値的研究" 25aKH-10
• 講演（共同研究者） "ワーム更新による並列化量子モンテカルロアルゴリズム" 25aKH-4
• 講演（共同研究者） "量子モンテカルロ法による正方格子SU(N)スピン模型の基底状態解析" 25aKH-8
• 講演（共同研究者） "シャストリーサザランド格子S=1/2反強磁性ハイゼンベルク模型の磁気秩序" 26pKM-1

#### 12 Aug 2013 "CMSI 第１部会「新物質・新量子相の基礎科学」 夏の学校 2013"に参加。

８月１２日から８月１６日、"CMSI 第１部会「新物質・新量子相の基礎科学」 夏の学校 2013"、山形蔵王。

#### 06 Aug 2013 Talk "Tensor network studies of quantum frustrated magnets" in the International Conference on Strongly Correlated Electron Systems (SCES2013).

From 5 Aug. 2013 to 9 Aug. 2013, the International Conference on Strongly Correlated Electron Systems (SCES2013), University of Tokyo, Tokyo.

#### 28 Jul 2013 Talk "Tensor network studies of quantum frustrated magnets" in Statistical Physics of Quantum Matter.

From 28 July 2013 to 31 July 2013, "Statistical Physics of Quantum Matter", National Taiwan University, Taipei, Taiwan.

#### 01 Jul 2013 Paper "Parallelized Quantum Monte Carlo Algorithm with Non-local Worm Update" is submitted.

PREPRINT arXiv:1307.0328
AUTHOR Akiko Masaki-Kato, Takafumi Suzuki, Kenji Harada, Synge Todo, Naoki Kaishima
ABSTRACT Based on the worm algorithm in the path-integral representation, we propose a general quantum Monte Carlo algorithm suitable for parallelizing on a distributed-memory computer by domain decomposition. Of particular importance is its application to large lattice systems of bosons and spins. A large number of worms are introduced and its population is controlled by a fictitious transverse field. For a benchmark, we study the size-dependence of the Bose-condensation order parameter of the hardcore Bose-Hubbard model with $L \times L \times \beta t =10240 \times 10240 \times 16$, using 3200 computing cores, which shows good parallelization efficiency.

#### 13 May 2013 Talk "Bayesian Inference in the Scaling Analysis of Critical Phenomena" in the seminar of theory of electrons in solids group in Osaka University.

13 May 2013, the seminar of theory of electrons in solids group, Deptertment of Physics, Osaka University, Osaka.

#### 29 Mar 2013 日本物理学会第６８回年次大会にて講演。

３月２６日から３月２９日、

• 講演 "脱閉じ込め臨界現象の普遍性" 29aXZD-8
• 講演（共同研究者） "正方格子SU(N)スピン模型の有限温度転移" 29aXZD-9
• 講演（共同研究者） "ワームアルゴリズムの並列化" 29aXZD-11

#### 22 Mar 2013 Talk "Valence bond solid order and phase transition of honeycomb lattice models" Z24.03 in APS March Meeting 2013, Baltimore, Maryland, USA.

From 18 March 2013 to 22 March 2013, APS March Meeting 2013, Baltimore, Maryland, USA.

#### 10 Dec 2012 Paper "Study of the Shastry Sutherland Model Using Multi-scale Entanglement Renormalization Ansatz" is submitted.

PREPRINT arXiv:1212.1999
AUTHOR Jie Lou, Takafumi Suzuki, Kenji Harada, and Naoki Kaishima
ABSTRACT We performed variational calculation based on the multi-scale entanglemnt renormalization ansatz, for the antiferromagnetic Heisenberg model on a Shastry Sutherland lattice (SSL). Our results show that at coupling ratio J'/J= 0.687(3), the system undergoes a quantum phase transition from the orthogonal dimer order to the plaquette valence bond solid phase, which then transits into the antiferromagnetic order above J'/J=0.75. In the presence of an external magnetic field, our calculations show clear evidences of various magnetic plateaux in systems with different coupling ratios range from 0.5 to 0.69. Our calculations are not limited to the small coupling ratio region, and we are able to show strong evidence of the presence of several supersolid phases, including ones above 1/2 and 1/3 plateaux. Such supersolid phases, which feature the coexistence of compressible superfluidity and crystalline long range order in triplet excitations, emerge at relatively large coupling ratio (J'/J>0.5). A schematic phase diagram of the SSL model in the presence of magnetic field is provided.

#### 03 Dec 2012 講演 "脱閉じ込め臨界現象のユニバーサリティ"、第３回 CMSI 研究会 〜超並列計算が拓く新しい計算物質科学〜。

１２月３日から１２月５日、 第３回 CMSI 研究会 〜超並列計算が拓く新しい計算物質科学〜、自然科学研究機構 岡崎コンファレンスセンター。

#### 16 Nov 2012 Paper "Numerical study of incommensurability of the spiral state on spin-1/2 spatially anisotropic triangular antiferromagnets using entanglement renormalization" is published in Physical Review B.

REFERENCE Physical Review B 86 (2012) 184421
DOI 10.1103/PhysRevB.86.184421
PREPRINT arXiv:1208.4306
ABSTRACT The ground state of an $S=1/2$ antiferromagnetic Heisenberg model on a spatially anisotropic triangular lattice, which is an effective model of Mott insulators on a triangular layer of organic charge transfer salts or Cs2CuCl4, is numerically studied. We apply a numerical variational method by using a tensor network with entanglement renormalization, which improves the capability of describing a quantum state. Magnetic ground states are identified for 0.7 <= J2 / J1 <= 1 in the thermodynamic limit, where J1 and J2 denote the innerchain and interchain coupling constants, respectively. Except for the isotropic case (J1 = J2), the magnetic structure is spiral with an incommensurate wave vector that is different from the classical one. The quantum fluctuation weakens the effective coupling between chains, but the magnetic order remains in the thermodynamic limit. In addition, the incommensurate wave number is in good agreement with that of the series expansion method.