東京大学生産技術研究所の李と申します。
羽田野研究室では、下記の通りセミナーを開催致します。
皆様の奮ってのご参加をお待ちしております。
なお、当研究室におけるセミナー情報は、次のリンクよりご覧頂けます。
hatano-lab.iis.u-tokyo.ac.jp/seminar-j.html
当セミナーは原則として現地会場での開催となりますが、オンライン参加をご希望の方はご連絡下さい。
＊本案内は複数のメーリングリストにお送りしております。重複して受け取られました方は何卒ご容赦下さい。
Dear All,
This is Jaeha Lee from the Institute of Industrial Science, the University of Tokyo.
We are pleased to announce an upcoming seminar as follows.
Information regarding our seminar series is available on our web site.
hatano-lab.iis.u-tokyo.ac.jp/seminar-e.html
Those who are interested are welcome to join us on-site. For those who wish to join us online, please feel free to contact us.
* Apologies if you have received multiple copies of this announcement.
記
日時：２０２５年０７月２４日（木）１４時００分〜 / Thursday, 24th July 2025, 14:00 JST –
場所：東京大学生産技術研究所 研究実験棟Ｉ大会議室 / The large conference room, Research and Testing Complex I, IIS, the University of Tokyo
来場：http://hatano-lab.iis.u-tokyo.ac.jp/access-j.html / hatano-lab.iis.u-tokyo.ac.jp/access-e.html
講師：西川秀明（Nishikawa Hideaki）さん（京大 / Kyoto U.）
演題：Energy and spin diffusion in the long-range interacting spin systems
要旨：
We investigate the energy and spin diffusion in the extensive long-range interacting spin systems.
First, we study energy diffusion in long-range interacting spin systems, where the interaction decays algebraically as $V(r) \propto r^{-\alpha}$ with the distance $r$ between the sites. We consider prototypical spin systems, the transverse Ising model, and the XYZ model in the $D$-dimensional lattice with a finite exponent $\alpha >D$ which guarantees the thermodynamic extensivity.
In one dimension, both normal and anomalous diffusion are observed, where the anomalous diffusion is attributed to anomalous enhancement of the amplitude of the equilibrium current correlation. We prove the power-law clustering property of arbitrary orders of joint cumulants in general dimensions. Applying this theorem to equal-time current correlations, we further prove several theorems leading to the statement that the sufficient condition for normal diffusion in one dimension is $\alpha > 3/2$ regardless of the models. The fluctuating hydrodynamics approach consistently explains L'{e}vy diffusion for $\alpha < 3/2$, which implies the condition is optimal. In higher dimensions of $D \geq 2$, normal diffusion is indicated as long as $\alpha > D$ [1].
Next, we also investigate spin diffusion in long-range interacting XXZ model, with a power-law exponent $\alpha>D$. We obtain the same scaling behavior for spin diffusion, both in one dimension and higher dimensions [2].
We expect this theoretical framework is broadly applicable to the transport phenomena in a wide class of long-range interacting systems.
[1] HN & K.Saito, arXiv:2502.10139.
[2] HN & K.Saito, in preparation.
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李 宰河
〒277-8574 千葉県柏市柏の葉５－１－５
東京大学生産技術研究所
電 話：04-7136-6962
メール：lee@iis.u-tokyo.ac.jp
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