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研究成果
2026.07.03
https://www.isct.ac.jp/ja/news/wrx6ltojyijx
東京科学大学（Science Tokyo） 理学院 物理学系の古田爽樹大学院生と賀川史敬教授（理化学研究所 創発物性科学研究センター チームディレクター）、理化学研究所 創発物性科学研究センター（CEMS）のYao Guang（ヤオ・グァン）特別研究員（研究当時）、軽部皓介ユニットリーダー、田口康二郎グループディレクター、小椎八重航上級研究員、于秀珍チームディレクターらの研究チームは、金属らせん磁性体であるCo8.5Zn8.5Mn3（コバルト・亜鉛・マンガン化合物）において、磁場下でらせん磁気構造の進む方向を電流で可逆制御できることを初めて実証しました。
本成果は、7月2日付（現地時間）の「Communications Materials」誌に掲載されました。
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お知らせ教員公募
2026.07.02
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セミナー
2026.06.29
講師：Dr. Flavio Ronetti（Aix Marseille University, France）
日時：令和8年7月7日（火）13:30-
場所：本館1階 M112 講義室Anyons, quasiparticles with exchange statistics intermediate between bosons and fermions, are among the most distinctive excitations of fractional quantum Hall systems. Their fractional charge has long been accessed through shot-noise measurements at quantum point contacts, but a direct and robust detection of their braiding statistics remains a central challenge. In this seminar, I will discuss several transport-based approaches to probing anyonic properties in fractional quantum Hall edge states.
First, I will show how the finite spatial width of anyons can strongly affect braiding-induced transport signatures, even when this width is extremely small. This effect is especially relevant for hierarchical states and provides a possible explanation for recent experiments at filling factor (ν=2/5). I will then discuss
photo-assisted shot noise as a tool to identify multiple tunneling charges in states with several edge modes, focusing on the case (ν=2/3), where different quasiparticle charges may tunnel simultaneously at a quantum point contact.
Finally, I will present proposals for directly measuring the anyonic statistical angle using controlled time-dependent transport. These setups rely on anyons emitted from a QPC source and braided either around a fractional quantum Hall droplet or through a closed-loop geometry on a single chiral edge. In these schemes, the time-dependent current and current cross-correlations carry signatures governed by the statistical phase, while suitable protocols allow the extraction of the anyonic angle without requiring independent knowledge of non-universal parameters. Together, these results highlight how edge transport can provide experimentally accessible and theoretically sharp probes of fractional charge, braiding, and anyonic statistics.
The following published papers are related to this work:
https://arxiv.org/abs/2311.15094
https://arxiv.org/abs/2502.15909
https://arxiv.org/abs/2503.17008
https://arxiv.org/abs/2506.09774連絡教員：物理学系 藤澤 利正（内線2750）
https://www.phys.sci.isct.ac.jp/wp/wp-content/uploads/2026/06/446.pdf
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セミナー
2026.06.24
講師：Professor Sven van Teeffelen（The University of Montreal, Montreal, CANADA ）
日時：令和8年7月1日（水）13:30-
場所：南5号館5階 503CD 大会議室 および Zoom*All living cells are bounded by envelopes that protect them from the environment and confer their sizes and shapes. These shapes help cells to spatially organize their internal biological processes, allowing them to divide and faithfully segregate genetic material to each daughter. Yet, we still know very little about how cells obtain and control cell shape, even in the arguably simplest and best understood organism: the rod-shaped Escherichia coli.
To resist a high intracellular osmotic pressure, bacteria and many other single-celled organisms are surrounded by a cell wall, an elastic, covalent meshwork of sugars and peptides. For walled cells to grow, they must enzymatically cut cell-wall bonds while inserting new cell-wall material to prevent envelope rupture. How do cells control a straight rod-like cell geometry with a well-defined diameter, while also maintaining cell-wall integrity and increasing cell length at a rate that accommodates biomass growth? We have made important progress in the past two decades.
Here, I will present two related vignettes that answer aspects of these questions in Gram-negative rod-shaped bacteria: First, I will present experiments showing that cells couple the global rate of envelope growth to metabolism, i.e., they increase their envelope in proportion to the production of biomass, likely at the level of the outer membrane. Second, I will present how mechanical forces and envelope curvature contribute to the regulation of cell shape locally, through cytoskeletal proteins and autolytic enzymes, based on coarse-grained computer simulations.※本セミナーは学術変革領域(A)「動的物質科学の創成 量子と古典の枠を超える」との共催です。
＊本 ZOOM セミナーに参加されます場合には、事前に下記より登録を済ませてください。https://zoom.us/meeting/register/_HDG8eelQfa4fMUVRtLP3A
当日会場にお越しいただけます方は、登録不要ですので、是非、対面でご参加ください。
連絡教員：物理学系 西口 大貴（内線2447）https://www.phys.sci.isct.ac.jp/wp/wp-content/uploads/2026/06/445.pdf
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研究成果
2026.06.10
Revealing optical activity in achiral crystals | Science Tokyo
Raman optical activity, long thought to require chiral molecules or magnetic order, has been demonstrated in an achiral, nonmagnetic crystal by researchers at Institute of Science Tokyo.
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セミナー
2026.06.02
【開催日変更】
講師：Dr. Ho Hsiao（Center for Computational Sciences, University of Tsukuba）
日時：令和8年6月24日（水）16:00-
場所：本館2階 290 物理学系輪講室In the context of Composite Higgs Models, where the standard model Higgs is interpreted as a pseudo Nambu-Goldstone Boson emerging from a new strong sector, baryons formed by matters in different representations, known as chimera baryons, could serve as top partners. The chimera baryon sharing the same quantum number as the top quark can mix with it, effectively lifting the mass of the top quark. We report our results of the spectrum of low-lying chimera baryons in the quenched approximation on a Sp(4) gauge theory. We perform spin and parity projections to separate the states and study their mass hierarchy. Particularly, we investigate the chiral extrapolation of chimera baryon masses. To accomplish this, we use a fitting function inspired by QCD chiral Effective Field Theory (EFT). Lastly, we present our current results using the dynamical fermions. 連絡教員：物理学系 関澤 一之（内線2463）
https://www.phys.sci.isct.ac.jp/wp/wp-content/uploads/2026/06/120tokubetsu-henkou.pdf
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セミナー
2026.05.28
講師：Dr. Alexis Poncet（CNRS, Laboratoire de physique à l'ENS de Lyon, Lyon, France ）
日時：令和8年6月8日（月）10:30-
場所：南5号館5階 503CD 大会議室 および Zoom*In systems far from thermal equilibrium, structure and dynamics are intertwined, leading to emergent phenomena such as collective motion in active matter or anomalous wave propagation in nonreciprocal systems. This talk explores the role of microscopic interactions in shaping these behaviors: What forms do they take? What are their consequences at macroscopic scales? And how can we infer them from experiments?
In the first part, I will present a study of self-propelled Janus particles (developed in the Nishiguchi lab), which exhibit coherent flocking at the collective level. Using a recent framework known as Stochastic Force Inference, we learned the microscopic interactions between particles [1]. These interactions not only reproduce experimental observables in simulations but also reveal a mechanism for flocking: pairwise torques that cause particles to turn away from their neighbors.
The second part focuses on flowing droplets with nonreciprocal hydrodynamic interactions, where left/right asymmetry gives rise to unexpected dynamics. Despite being overdamped, a 1D stream of such droplets supports nonlinear waves due to nonreciprocal coupling. Theoretically, we predict solitary waves described by the Korteweg–de Vries (KdV) equation (or KdV-Burgers with damping) [2]. A physics-informed neural network further uncovers this dynamics directly from experimental data.
If time permits, I will briefly discuss two ongoing theoretical projects on active and nonreciprocal systems: (1) how memory effects in viscoelastic media alter Motility-Induced Phase Separation of active particles, and (2) how Kardar-Parisi-Zhang fluctuations are evidenced in a 1D lattice model with nonreciprocal interactions.
[1] Hem, Poncet, Ronceray, Nishiguchi & Démery, Soft Matter 21 (37), 7257-7269 (2025)
[2] Colen, Poncet, Bartolo & Vitelli, Physical Review Letters 133 (10), 107301 (2024)
※本セミナーは学術変革領域(A)「動的物質科学の創成 量子と古典の枠を超える」との共催です。
＊Zoom 登録リンク：https://zoom.us/meeting/register/qw3pWA-kTjW7F01RXWqJSg連絡教員：物理学系 西口 大貴（内線2447）
https://www.phys.sci.isct.ac.jp/wp/wp-content/uploads/2026/05/121tokubetsu.pdf
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セミナー
2026.05.22
講師：鈴木 史花 氏（東京大学 素粒子物理国際研究センター）
日時：令和8年6月10日（水）13:30-
場所：本館2階 290 物理学系輪講室The Kibble–Zurek mechanism (KZM) combines Kibble’s observation of topological defects formation in cosmological phase transitions with Zurek’s theory relating their density to critical slowing down, and hence to the universality class of a second-order phase transition. The resulting KZM predicts defect density as a function of the quench rate in second-order phase transitions, in both classical and quantum settings. It has applications across a wide range of fields, including condensed matter physics, cosmology, and quantum computing.
In this talk, I will discuss extensions of KZM beyond its original formulation. I will show how KZM can be combined with nucleation theory to describe weakly first-order phase transitions, how nonadiabatic excitation formulas can be generalized to exotic quantum phase transitions, and how order-parameter dynamics offers a new perspective on KZM. I will also discuss how machine learning can provide deeper insight into second-order phase transitions beyond the conventional KZM framework.連絡教員：物理学系 藤井 啓資（内線2136）
https://www.phys.sci.isct.ac.jp/wp/wp-content/uploads/2026/05/444.pdf
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研究成果
2026.05.22
https://www.isct.ac.jp/ja/news/ati2jkvlcrqd
東京科学大学（Science Tokyo）理学院 物理学系の佐藤琢哉教授、楠野楽到大学院生、東京大学 大学院工学系研究科の木村剛教授、北海道大学 大学院工学研究院の渡邉光准教授らの研究グループは、中心対称性を持ち非磁性な結晶であるNiTiO3（チタン酸ニッケル）において、ラマン光学活性（Raman Optical Activity, ROA）が生じることを明らかにしました。
本成果は、米国物理学会誌「Physical Review Letters 」に5月19日（現地時間）付で掲載されるとともに、特に重要な論文としてEditors’ Suggestion に選出されました。
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セミナー
2026.05.19
講師：Professor Miyatsu Tsuyoshi（Soongsil University, Seoul, Korea）
日時：令和8年6月８日（月）16:00-
場所：本館2階 227C 物理学系輪講室The quark-meson coupling (QMC) model describes nuclear many-body systems in terms of quark degrees of freedom. In this model, quarks are confined inside each baryon and interact self-consistently with scalar- and vector-meson fields generated by the surrounding nuclear medium. As a result, the internal structure of baryons changes with density, producing density-dependent effective masses and baryon-meson couplings. This mechanism offers a microscopic interpretation of nuclear saturation and provides a natural bridge between baryon structure and nuclear many-body dynamics.
In this seminar, I will review the basic idea of the original QMC model and its applications to nuclear matter and finite nuclei, following the developments summarized in the review by Saito, Tsushima, and Thomas. I will then discuss several extensions and applications, including hyperonic matter, chiral effects, neutron-star equations of state, and the role of Fock terms and tensor couplings in dense matter. Finally, I will introduce a recent development toward quarkyonic matter, where baryonic and quark degrees of freedom coexist in a high-density regime. This talk aims to clarify how in-medium baryon structure variations can connect finite nuclei, dense matter, neutron stars, and possible quarkyonic phases within a common microscopic perspective.連絡教員：物理学系 関澤 一之（内線2463）
https://www.phys.sci.isct.ac.jp/wp/wp-content/uploads/2026/05/443.pdf
