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Date: Tue, 15 Sep 2026 00:07:31 +0900
To: sg-l__AT__yukawa.kyoto-u.ac.jp
Subject: [Sg-l:10631] QUP Colloquium - (Sep. 18, 3:00 PM JST) - Ryo Shimano (U. Tokyo)
From: Volodymyr Takhistov (Sg-l 経由) 

Dear Colleagues,

Of possible interest, we are sharing an announcement of an upcoming QUP 
Colloquium by Prof. Ryo Shimano on Friday, September 18. Details are below.

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*Speaker:* Ryo Shimano (U. Tokyo), Director of Cryogenic Research Center

*Title:*  Searching for the Higgs mode and its cousins in superconductors

*Date/Time (JST):* Friday, Sep. 18, 3:00 PM

*Location:* (hybrid, in-person + Zoom) KEK Tsukuba Campus, QUP Seminar Hall

*Webpage* (including Zoom info): https://kds.kek.jp/event/61273/

*Abstract:* Spontaneous symmetry breaking (SSB) is a unified concept 
bridging particle physics and condensed matter. When the U(1) gauge 
symmetry in a superconductor is spontaneously broken, the complex order 
parameter acquires a Mexican-hat potential, giving rise to two 
fundamental collective excitations: the phase mode (Nambu-Goldstone 
mode) and the amplitude mode. While the phase mode is absorbed to render 
the photon massive via the Anderson-Higgs mechanism, the amplitude mode 
persists as a scalar excitation—the condensed-matter analogue of the 
Higgs boson. Because it carries no net charge or spin, this Higgs mode 
does not couple to electromagnetic fields at the linear order (A), 
making its direct observation notoriously difficult for over half a 
century [1-3]. In this colloquium, I will show how modern nonlinear 
terahertz spectroscopy overcomes this selection rule via A^2 coupling, 
review the key advances in Higgs spectroscopy over the past decade, and 
discuss future directions toward unconventional superconductors with 
exotic order parameters [4-6].

[1] For a recent review, see e.g., Ryo Shimano and Naoto Tsuji, Ann. 
Rev. Cond. Mat. Phys. 11, 103-124 (2020).
[2] R. Matsunaga, Y. I. Hamada, K. Makise, Y. Uzawa, H. Terai, Z. Wang, 
and R. Shimano,
Phys. Rev. Lett. 111, 057002 (2013).
[3] R. Matsunaga, N. Tsuji, H. Fujita, A. Sugioka, K. Makise, Y. Uzawa, 
H. Terai, Z. Wang, H. Aoki, and R. Shimano, Science 345, 1145 (2014).
[4] K. Katsumi, N. Tsuji, Y. I. Hamada, R. Matsunaga, J. Schneeloch, R. 
D. Zhong, G. D. Gu, H. Aoki, Y. Gallais, and R. Shimano, Phys. Rev. 
Lett. 120, 117001 (2018).
[5] S. Nakamura, Y. Iida, Y. Murotani, R. Matsunaga, H. Terai, and R. 
Shimano, Phys. Rev. Lett. 122, 257001 (2019).
[6] H. Matsumoto, S. Neri, T. Kobayashi, A. Maeda, D. Manske, R. 
Shimano, arXiv:2507.14466

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We welcome your participation.

Best Regards,
Toshiyuki Azuma, Tatsumi Nitta, Volodymyr Takhistov
for the QUP Colloquium organizers