Joint Colloquia
ASIAA/CCMS/IAMS/LeCosPA/NTU-Phys/NTNU-Phys
Coordinators:
Chia-Hung Chang (NTNU Phys), Ssu-Yen Huang (NTU Phys), Shao-Yu Chen (CCMS), Cheng-Tien Chiang (IAMS), Jiwoo Nam (LeCosPA), Tomomi Sunayama (ASIAA), Shang-Min Tsai (ASIAA)
Embedded Files
Feb. 24, 2026 (week 01)
Ting-Wen Lan
Ting-Wen Lan
Assistant Professor, National Taiwan University
Tracing Gas In and Around Galaxies
Host: Ssu-Yen Huang
Time: 2:20 pm ~ 4:20 pm
Place: Chin-Pao Yang Lecture Hall, R104, CCMS-New Phys. building
Abstract
Galaxies evolve by regulating the amount of gas in and around them. By observationally exploring the connections between gas and galaxies, we can better understand the physical mechanisms driving galaxy evolution. In this talk, I will present results from a series of studies focused on exploring and characterizing the properties of gas in and around galaxies. I will first introduce the Dark Energy Spectroscopic Instrument (DESI), which provides the largest spectroscopic dataset available for extracting gas properties through emission and absorption line features. I will then present three major research directions: (1) exploring the diversity of gas profiles within galaxies, (2) a comprehensive characterization of gas surrounding galaxies, and (3) the development of the DESI-II survey. I will show that by combining large multi-wavelength datasets with statistical and machine learning techniques, we can not only obtain observational measurements with unprecedented precision, but also uncover new astrophysical phenomena — offering deeper insight into the underlying physical processes at play.
Brief Bio
Ting-Wen Lan is an Assistant Professor in the Graduate Institute of Astrophysics and the Department of Physics at National Taiwan University. He is a Yushan Young Fellow awarded by the Ministry of Education and a joint Assistant Research Fellow at Academia Sinica Institute of Astronomy and Astrophysics. He received his PhD in astrophysics from Johns Hopkins University in 2016 and held independent postdoctoral research positions at the Kavli IPMU at the University of Tokyo and the University of California, Santa Cruz, before joining NTU in 2021. His research focuses on galaxy astrophysics, combining large observational datasets with statistical and machine learning techniques to uncover novel astrophysical signals.
Video
20260224.mp4Mar. 3, 2026 (week 02)
Shau-Yu Lan
Shau-Yu Lan
Associate Professor, National Taiwan University
Fast Quantum Gas Formation via Electromagnetically Induced Transparency Cooling
Host: Ssu-Yen Huang
Time: 2:20 pm ~ 4:20 pm
Place: Chin-Pao Yang Lecture Hall, R104, CCMS-New Phys. building
Abstract
Ultracold quantum gases play a pivotal role in many-body physics, quantum sensing, and quantum simulation. Over time, methods such as evaporative cooling in bulk ensembles and precision laser cooling techniques have been employed to achieve quantum degeneracy in atomic gases. The pursuit of a simpler, faster way to form quantum gases thus holds significant promise for advancing the field. In this talk, I will report on our creation of a quantum gas by cooling individual rubidium atoms pinned in a three-dimensional optical lattice using electromagnetically induced transparency and adiabatic expansion. After just 10 milliseconds of cooling, we verify the phase transition from a thermal to a quantum gas by adiabatically transferring the atoms into optical dipole traps. We observe the collapse of atoms in three-dimensional traps, a distinctive hallmark of a quantum gas with negative scattering length. Our results introduce a versatile and fast approach to achieving quantum degenerate gases with minimal time and resource requirements.
Brief Bio
Dr. Shau-Yu Lan earned his B.S. from National Tsing Hua University in 2002 and received his Ph.D. from Georgia Institute of Technology in 2009. He then conducted postdoctoral research at the University of California, Berkeley. In 2013, He joined Nanyang Technological University in Singapore as a National Research Foundation (NRF) Fellow and Nanyang Assistant Professor. In 2023, He transitioned to the Department of Physics at National Taiwan University.
Video
20260303.mp4Mar. 10, 2026 (week 03)
Tien-Ming Chuang
Tien-Ming Chuang
Associate Research Fellow, Institute of Physics, Academia Sinica
Disorder Driven Electronic Smectic Phase and Charge Density Wave in a Nonsymmorphic Sb Square-net Semimetal
Host: Ssu-Yen Huang
Time: 2:20 pm ~ 4:20 pm
Place: Chin-Pao Yang Lecture Hall, R104, CCMS-New Phys. building
Abstract
Electronic liquid crystal (ELC) phases are spontaneous symmetry breaking states believed to arise from strong electron correlation in quantum materials such as cuprates and iron pnictides. Here, we report a direct observation of a smectic phase in a weakly correlated non-symmorphic Sb square-net semimetal, GdSbxTe2-x. Incommensurate smectic charge modulation and intense local unidirectional nanostructure, which coexist with Dirac fermions across Fermi level, are visualized by using spectroscopic imaging-scanning tunneling microscopy. As materials with highly mobile carriers are mostly weakly correlated, the discovery of such an ELC phase are anomalous and raise questions on the origin of their emergence. Specifically, we demonstrate how chemical substitution generates these symmetry breaking phases before the system undergoes a charge density wave (CDW)-orthorhombic structural transition [1]. Furthermore, the local unidirectional nanostructures appear coupled strongly with the CDW order. We will discuss the role of disorder in comparison with the recent claim of the bond density wave in CeSbTe [2]. Together, our results highlight the importance of impurities in realizing ELC phases and present a new material platform for exploring the interplay among quenched disorder, topology and electron correlation.
1. B. Venkatesan et al., npj Quantum Materials 10, 56 (2025).
2. X. Que et al., Nature Communications 16, 3053 (2025).
Brief Bio
Tien-Ming Chuang is an Associate Research Fellow at the Institute of Physics, Academia Sinica. He earned his PhD in Physics from the University of Texas at Austin in 2006, followed by postdoctoral fellowships at Cornell University and the National High Magnetic Field Laboratory between 2007 and 2011. Dr. Chuang joined Academia Sinica in 2011. His research focuses on the microscopic investigation of quantum materials, specifically unconventional superconductors and topological materials, using spectroscopic-imaging scanning tunneling microscopy. He is a recipient of the 2017 Wu Ta-You Memorial Award and the 2012 Kenda Foundation Young Scholar Award.
Mar. 17, 2026 (week 04)
Masaki Azuma
Masaki Azuma
Professor, Institute of Integrated Research, Institute of Science Tokyo
Magnetization Reversal by Electric Field in Co Substituted BiFeO3 Thin Films
Host: Wei-Tin Chen
Time: 2:20 pm ~ 4:20 pm
Place: Chin-Pao Yang Lecture Hall, R104, CCMS-New Phys. building
Abstract
Electric field manipulation of magnetization is intensively investigated because of potential application in low-power-consumption non-volatile magnetic memory devises. Ferroelectric BiFeO3 has a cycloidal space-modulated spin structure with a periodicity of 62 nm superimposed on the G-type antiferromagnetic structure which prohibits the appearance of net ferromagnetic magnetization due to spin canting. We have found a spin structure transition from low-temperature cycloidal one to high-temperature collinear one with spontaneous magnetization of 0.03 μB/f.u. confined in a magnetic easy plane perpendicular to the electric polarization is generated by Dzyaloshinskii-Moriya interaction at ~200 K in rhombohedral BiFe1-xCoxO3 [1-3]. (001)pc oriented thin films fabricated by pulsed laser deposition on GdScO3 (110) substrate has out-of-plane component of magnetization which can be observed by magnetic force microscopy (MFM). It is demonstrated that the out-of-plane magnetization can be reversed accompanying electric polarization reversal using piezo response force microscopy (PFM) at room temperature [4]. Magnetization reversal by in-plane electric field was achieved in (110) oriented BFCO film [5]. Changes in ferroelectric and magnetic domains after poling in BiFe0.1Co0.9O3 nanodots with topological domain structures will also be discussed [6,7].
1. H. Yamamoto, T. Kihara, K. Oka, M. Tokunaga, K. Mibu, M. Azuma, J. Phys. Soc. Jpn. 85, 064704 (2016).
2. H. Yamamoto, Y. Sakai, K. Shigematsu, T. Aoyama, T. Kimura, M. Azuma., Inorg. Chem., 56, 15171 (2017).
3. H. Hojo, R. Kawabe, K. Shimizu, H. Yamamoto, K. Mibu, K. Samanta, T. Saha-Dasgupta, M. Azuma, Adv. Mater., 29, 160313 (2017).
4. K. Shimizu, R. Kawabe, H. Hojo, H. Shimizu, H. Yamamoto, M. Katsumata, K. Shigematsu, K. Mibu, Y. Kumagai, F. Oba, M. Azuma, Nano Lett., 19, 1767-177 (2019).
5. T. Itoh, K. Shigematsu, H. Das, P. Meisenheimer, K. Maeda, K. Lee M. Manna, S. P. Reddy, S. Susarla, P. Stevenson, R. Ramesh and M. Azuma, Adv. Mater., 37, 2419580 (2025).
6. K. Ozawa, Y. Nagase, M. Katsumata, K. Shigematsu, M. Azuma, ACS Appl. Mater. Interfaces, 16, 20930 (2024).
7. K. Lee, P. Meisenheimer, P. Stevenson, Y. Nagase, K. Shigematsu, R. Ramesh, M. Azuma, under review.
Brief Bio
After bachelor and master degrees, professor Masaki AZUMA obtained a PhD in chemistry from Kyoto University in 1995. From 1995 to 2010, he was assistant and associate professors at Institute for Chemical Research, Kyoto University and from 2010 he is a professor at Tokyo Institute of Technology which is now Institute of Science Tokyo. He is also a project leader at Kanagawa Institute of Industrial Science and Technology. His interests are related to synthesis, structural analysis and functional properties of advanced oxide materials.
Video
20260319.mp4Mar. 24, 2026 (week 05)
Chang-Tse Hsieh
Chang-Tse Hsieh
Assistant Professor, Department of Physics, National Taiwan University
Why Some Quantum Systems Cannot Be Simple—the Power of Symmetry in Many-Body Physics
Host: Ssu-Yen Huang
Time: 2:20 pm ~ 4:20 pm
Place: Chin-Pao Yang Lecture Hall, R104, CCMS-New Phys. building
Abstract
A central theme in modern condensed matter physics is that the collective behavior of many interacting particles can be far richer than what one might infer from single-particle physics alone. In particular, strongly correlated systems often exhibit emergent phenomena governed not by microscopic details, but by more general physical principles. In this talk, I will discuss how symmetry provides a powerful way to constrain the possible low-energy behavior of quantum many-body systems. A classic example is the Lieb-Schultz-Mattis theorem, which shows that certain one-dimensional quantum magnets cannot have a unique gapped ground state if they preserve spin-rotation and lattice-translation symmetries. I will then present recent generalizations of this idea to a broader class of quantum spin systems, illustrating how symmetry can reveal robust features of quantum matter without requiring the full solution of a complicated many-body problem.
Brief Bio
Chang-Tse Hsieh is an Assistant Professor in the Department of Physics at National Taiwan University. He received his PhD in Physics from the University of Illinois Urbana-Champaign in 2017. He subsequently held joint postdoctoral positions at Kavli IPMU and the Institute for Solid State Physics at the University of Tokyo, and later served as a Special Postdoctoral Researcher at RIKEN, before joining NTU in 2022. His research lies in theoretical condensed matter physics and high-energy physics, particularly at their interface. He is primarily interested in topological phenomena, entanglement, and criticality in quantum matter, as well as nonperturbative aspects of many-body systems.
Video
20260324.mp4Page updated
Report abuse