東京科学大学 理学院 物理学系
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This seminar will review experimental searches for the H-dibaryon through various reactions, focusing specifically on the latest results from the J-PARC E42 experiment. This experiment investigates the H-dibaryon near the Lambda Lambda and Xi- p mass thresholds. The E42 has collected thousands of Lambda Lambda production events from (K-, K+) reactions off a 12C target at 1.8 GeV/c. We are on the verge of publishing our results, and this talk will discuss the nature of the H-dibaryon, offering insights into exotic baryon spectroscopy and extending our understanding to further multiquark states.

連絡教員：物理学系　慈道　大介（内線2083）

https://www.phys.sci.isct.ac.jp/wp/wp-content/uploads/2026/01/434.pdf

Standard hydrodynamics serves as a successful macroscopic description of fluid motion, ranging from engineering applications to turbulent flows. However, this framework is inherently deterministic and neglects the fluctuations that inevitably arise due to their underlying atomic structure. In particular, these fluctuations govern fluid phenomena at the mesoscopic scale between the microscopic and macroscopic scales. Fluctuating hydrodynamics extends the classical description by incorporating thermal fluctuations, leading to a more accurate description of such mesoscopic transport phenomena.
Recently, we analyzed the strong non-equilibrium fluctuations exhibited by fluids subjected to uniform gradients, such as single-component fluids under a shear flow or a temperature gradient and multi-component fluids under a concentration gradient [1-3]. These phenomena are one of the most well-established examples requiring a fluctuating hydrodynamic description, having been precisely observed in microgravity experiments. We performed direct numerical simulations (DNS) of the fluctuating hydrodynamic equations, and investigated the properties of energy dissipation and fluid behavior in the inviscid limit. In this seminar, I will present these findings alongside a historical review of the development and analysis of fluctuating hydrodynamics.

[1] HN, and K. Yokota, Phys. Rev. E 111, L063401 (2025)
[2] HN, Y. Minami, and K. Saito, arXiv:2502.15241(2025)
[3] HN, and Y. Minami, arXiv:2511.17851 (2025)

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/2026/01/433ーhenkou.pdf

The interior of a neutron star is expected to be occupied by neutron superfluids. While the outer region should be filled by 1S0 superfluids consisting of a conventional singlet pairs of neutrons, the inner core may be 3P2 superfluids consisting of a condensate of spin-triplet p-wave Cooper pairs of neutrons with total angular momentum J=2 . This has rich topological structures in both momentum and real spaces: it is a topological superfluid and admits various topological defects such as half-quantum non-Abelian vortices, domain walls, surface topological defects, boojums, and so on. I will give a review of the current status of 3P2 superfluids with a particular attention to vortices and possible applications to pulsar glitches.

※Zoom情報：https://zoom.us/meeting/register/6aN7eizNRL–W58_kNle8A

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/2025/12/432.pdf

https://cmsp.phys.s.u-tokyo.ac.jp/

理学院 物理学系の花井亮准教授が、第20回（2025年度）凝縮系科学賞を受賞しました。表彰式は11月27日に行われました。

The superradiant phase transition (SRPT) is a second-order phase transition where a static electric or magnetic field is ordered spontaneously due to an ultrastrong interaction with matters in thermal equilibrium. Although the SRPT has not been observed since its first prediction in 1973, its magnonic (spin-wave) version was confirmed in a magnetic material ErFeO3 recent years [1-3]. In this seminar, we will present experimental results [1,3] and theoretical background [2] of this magnonic SRPT. In addition, thermal-equilibrium quantum squeezing obtained at the SRPT critical point [4] will also be presented. The quantum technologies like quantum computing have been developed basically based on non-equilibrium phenomena. Because quantum states in those phenomena are usually excited states in systems of interest, such states are easily destroyed due to a variety of decoherence phenomena. In contrast, the SRPT provides quantum squeezing in the most stable state of systems in thermal equilibrium, thus its squeezing is robust against decoherence, which might give us a foundation of decoherence-robust quantum technologies.

[1] X. Li, M. Bamba, N. Yuan, Q. Zhang, Y. Zhao, M. Xiang, K. Xu, Z. Jin, W. Ren, G. Ma, S. Cao, D. Turchinovich, and J. Kono, Observation of Dicke cooperativity in magnetic interactions. Science 361, 794–797 (2018).
[2] M. Bamba, X. Li, N. Marquez Peraca, and J. Kono, Magnonic superradiant phase transition. Communications Physics 5, 3 (2022).
[3] D. Kim, S. Dasgupta, X. Ma, J.-M. Park, H.-T. Wei, X. Li, L. Luo, J. Doumani, W. Yang, D. Cheng, R. H. J. Kim, H. O. Everitt, S. Kimura, H. Nojiri, J. Wang, S. Cao, M. Bamba, K. R. A. Hazzard, and J. Kono, Observation of the magnonic Dicke superradiant phase transition. Sci. Adv. 11, eadt1691 (2025).
[4] K. Hayashida, T. Makihara, N. Marquez Peraca, D. Fallas Padilla, H. Pu, J. Kono, and M. Bamba, Perfect intrinsic squeezing at the superradiant phase transition critical point. Sci. Rep. 13, 2526 (2023).

連絡教員：藤井　啓資（内線2136）

https://www.phys.sci.isct.ac.jp/wp/wp-content/uploads/2025/12/431.pdf