Fall 2024 Schedule
Sep. 03, 2024 ( Week 01)
Cheng Chin
James Franck institute, Enrico Fermi institute and Department of Physics University of Chicago
Quantum simulation quantum information control with ultracold atoms
Host: Po-Ti Chang
Time: 2:20 pm - 4:20 pm
Place: Room 104, CCMS-New Phys. building
Abstract
Laser cooling and control of atoms embarks an exploration into novel quantum phenomena and information processing.
New tools to precisely manipulate atoms have led to emulate complex systems in nature and reveal exotic quantum phenomena.
I will outline in this talk the basics of quantum control, as well as quantum simulation relevant to cosmology and quantum chemistry. Finally I will introduce our new experiments to gain full control of individual atoms toward a scalable quantum simulation platform.
Brief Bio
Cheng Chin earned his B.S. in Science from National Taiwan University and Ph.D. in Physics from Stanford University in 2001.
He joined the University of Chicago in 2005 as a professor in the Physics Department.
Cheng Chin's research interests include bosonic and fermionic quantum gases, few-body physics, quantum simulation and quantum information control.
Sep. 10, 2024 ( Week 02)
Danru Qu
Center for Condensed Matter Sciences,National Taiwan University
Unveiling a novel class of magnetism: the altermagnetism
Host: Shao-Yu Chen
Time: 2:20 pm - 4:20 pm
Place: Room 104, CCMS-New Phys. building
Abstract
The field of magnetism has seen a surge of interest in a novel classification known as altermagnetism over the past few years [1]. This interest is driven by the unique physical properties of altermagnetic materials, which takes advantages of both conventional antiferromagnets and ferromagnets through the altermagnetic spin-splitting effect (ASSE). The non-relativistic ASSE enables the generation of not only a longitudinal spin polarized current, but also a transverse pure spin current upon the injection of a charge current along certain crystal orientations. However, experimentally unequivocal observation of the ASSE is challenging. This difficulty arises from the inevitable mixing of ASSE with the spin Hall effect (SHE) caused by the material's relativistic spin-orbit coupling and the ASSE's dependence on the hard-to-probe and hard-to-control Néel vectors.
In this talk, I will discuss our approach in addressing these challenges in the study of ASSE in RuO2 [2]. Our experimental observations revealed a highly anisotropic spin-to-charge conversion in the epitaxial RuO2 thin film. We attribute the anisotropy to an altermagnetic origin by ruling out the complication of an anisotropic SHE. We found the IASSE exhibited an opposite sign compared to the inverse spin Hall effect (ISHE). Remarkably, the efficiency of the IASSE was found to be consistently 70% of that of the ISHE in RuO2 for thicknesses ranging from 5 nm to 32 nm. Furthermore, we demonstrated that the ASSE/IASSE effects are observable only when the Néel vectors are well-aligned by modifying the Néel vector domains via RuO2 crystallinity through different substrates. Interestingly, the shape of the thermal voltage hysteresis loop is anisotropic and is consistent with the anisotropic magnetic hysteresis loop of YIG, which verifies the [001] orientation of the RuO2 Néel vectors. Our study provides significant insights into the spin-splitting effect in altermagnetic materials, paving the way for future advancements in spintronic technologies.
Brief Bio
Danru Qu is an assistant research fellow at the Center for Condensed Matter Sciences (CCMS), National Taiwan University.
Before joining CCMS, she worked as a postdoctoral fellow at the Institute of Physics (IOP), Academia Sinica and the Institute for Solid State Physics (ISSP), University of Tokyo.
She was awarded the Japan Society for the Promotion of Science (JSPS) postdoctoral fellowship during her stay in Japan.
She got her Ph. D degree in Physics from the Johns Hopkins University, and bachelor degree from the University of Science and Technology of China.
Her research interest is the interactions among spin, charge and heat in novel magnetic materials, topological materials, magnetic insulators and their heterostructures. She recently received the 2030 Research Project for Emerging Young Scholars from the National Science and Technology Council.
Sep. 17, 2024 ( Week 03 )
Mid-Autumn Festival
Sep. 24, 2024 ( Week 04)
Hung-Yu Yang
Department of Electrical and Computer Engineering, University of California, Los Angeles
Supercurrent Diodes and their Applications in Quantum Computing
Host: Po-Ti Chang
Time: 2:20 pm - 4:20 pm
Place: Room 104, CCMS-New Phys. building
Abstract
A supercurrent diode is a superconductor where electric current flows more easily in one direction than the other.
This effect is closely tied to the symmetry of the superconducting state and has exciting applications in quantum computing.
First, they provide evidence for unconventional quantum states that could lead to robust quantum bits (qubits), potentially extending the lifespan of quantum information.
Our research on supercurrent diodes in iron-based superconductors has revealed special symmetries representative of these topological quantum states.
Second, supercurrent diodes, akin to semiconductor diodes, offer practical applications in cryogenic electronics, which are crucial for controlling quantum computers at extremely low temperatures.
By strategically designing the symmetry of superconducting heterostructures with multiferroic materials, our latest breakthrough involves a supercurrent diode that can withstand strong magnetic fields, meeting industrial standards for the first time. These advancements in supercurrent diode research and low-dimensional superconducting heterostructures hold significant implications for developing powerful quantum computers.
Brief Bio
Dr. Hung-Yu Yang is a postdoctoral researcher at the University of California, Los Angeles. He received his B.S. in Physics from National Tsing Hua University, and Ph.D. in Physics from Boston College.
He has authored and co-authored over 20 research papers in high-quality peer-reviewed journals, including Nature Materials, Nature Communications, Physical Review Letters, Physical Review B, etc.
He actively serves the scientific community as an APS Career Mentoring Fellow, invited speaker and session chair of APS March Meeting, reviewer for international journals and government funding agencies.
His research focuses on engineering topological quantum states by combining electronic band topology, magnetism, and superconductivity. His work aims to advance our understanding of quantum materials and pave the way for new quantum technologies, such as robust quantum computers and cryogenic electronic devices.
Oct. 01, 2024 ( Week 05)
Tay-Rong Chang
Department of Physics, National Cheng Kung University, Taiwan.
Center for Quantum Frontiers of Research & Technology (QFort), Taiwan
Physics Division National Center for Theoretical Sciences, Taiwan.
Electronic structure of topological materials
📹
Host: Po-Ti Chang
Time: 2:20 pm - 4:20 pm
Place: Room 104, CCMS-New Phys. building
Abstract
Topological phases in condensed matter physics have gained significant attention, moving beyond Landau’s symmetry-breaking paradigm.
Initially, research focused on topological insulators (TIs), where 3D TIs show a bulk energy gap due to spin-orbit coupling and gapless surface states protected by time-reversal symmetry.
Recently, the focus shifted to topological semimetals (TSMs), such as Dirac, Weyl, and nodal-line semimetals.
Dirac and Weyl semimetals, 3D analogs of graphene, feature linear bulk band dispersion, while nodal-line semimetals exhibit 1D nodal loops in the Brillouin zone.
In contrast to their nonmagnetic counterparts, magnetic topological materials, including antiferromagnetic TIs, axion insulators, and Chern insulators, have sparked growing interest due to their unique states and potential to explore symmetry, magnetism, and correlations.
This presentation will review material predictions and experimental phenomena in both nonmagnetic and magnetic topological systems using first-principles calculations.
Brief Bio
Tay-Rong Chang is a Professor of Physics and serves as the Principal Investigator of the Tainan Hub at the National Center for Theoretical Sciences, National Cheng Kung University.
With over a decade of experience in theoretical condensed matter physics, his expertise spans first-principles simulations, tight-binding modeling, and topology/symmetry analysis.
His primary research focuses on discovering novel topological materials and low-dimensional materials with potential applications in next-generation spintronics and quantum computing.
Oct. 08, 2024 ( Week 06)
You-Sheng Li
Department of Physics, National Taiwan University
Tuning Quantum Materials
Host: Po-Ti Chang
Time: 2:20 pm - 4:20 pm
Place: Room 104, CCMS-New Phys. building
Abstract
Quantum materials possess exotic quantum phenomena arising from interplay of charge, spin, orbitals and lattice.
Materials with strong electron-electron correlation show particularly rich physics in their phase diagrams due to complex interactions, leading to different ground states under different circumstances.
My research interest mainly focuses on unconventional superconductors. Recently, uniaxial stress becomes a general tuning knob in studying quantum materials. In this talk, I will take Sr₂RuO₄ as an example to demonstrate versatility of the uniaxial stress techniques.
I will discuss our main findings based on the thermodynamic probes I have developed.
Brief Bio
Dr. You-Sheng Li earned his B.S. and M.S. from National Tsing Hua University in 2006 and 2009.
He received his Ph.D. from University of St Andrews (UK) in 2018. He then conducted postdoctoral research at Universität Würzburg, Germany in 2019 and Max Planck Institute for Chemical Physics of Solids, Germany from 2020 to 20203.
In 2024, he joined Department of Physics at National Taiwan University as an assistant professor.
Oct. 15, 2024 ( Week 07)
Alireza Moshfegh
Department of Physics and Nanosci. & Nanotechnol. Center Institute for Convergence Sci. & Technol. Sharif University of Technology, Tehran, Iran.
Recent Trends in Semiconductor Photocatalysis
Host: Chen, Li-Chyong
Time: 2:20 pm - 4:20 pm
Place: Room 104, CCMS-New Phys. building
Abstract
The world's total primary energy consumption was about ~ 6.2 x 1020 J in 2023 and it is expected to reach double by 2050.
On the other hand, about 80% of today's total energy supply originates from fossil fuels (e.g. petroleum, gas and coal) that are major responsible for air and water pollution.
In addition, these non-renewable energy sources are discharging a large amount of CO2 in the environment after their combustion which creates severe problems such as global warming and climate changes.
Therefore, it is an urgent need to develop renewable energy technologies and resources that neither rely on fossil fuels nor emit carbon dioxide for safer society and sustainable growth.
Photocatalysis as a surface phenomenon is one of the most important advanced oxidation processes (AOP) is a promising and environmental-friendly method that applies in various industrial wastewater treatment.
Most of semiconductors use as photocatalysts in these processes face challenges like low optical absorption, insufficient charge carrier separation and electron-hole recombination. After a brief history and introduction on principles of semiconductor photocatalysis, physics and technology of different nanostructures (0D, 1D and 2D) and novel 2D materials as semiconductor photocatalysts are presented.
Several strategies on materials design and optimization of photocatalysts and influencing factors on photocatalytic reactions will be described. Then three types of photocatalytic reactions for clean energy production and environmental remediation namely i) photoelectrochemical (PEC) water splitting towards hydrogen generation, ii) photocatalytic degradation of major wastewater pollutants such as dyes and drugs and iii) CO2 reduction to value-added products, will be briefly introduced.
Then, role of surfaces/interfaces of photocatalysts in improving reaction yield under visible light and UV photoirradiation as well as kinetics and mechanism of the reactions will be summarized. Finally, recent advances and prospects of semiconductor photocatalysts will be presented.
Brief Bio
Professor Alireza Moshfegh received his PhD in Physics at University of Houston, Texas (USA) in 1990.
After two years Post-Doctoral research activity in the USA, he joined Department of Physics at the Sharif University of Technology (SUT) in Tehran, Iran.
Since then, he has taught many undergraduate and graduate courses. He is the founder of Vacuum Society of Iran (VSI) and its past president (2004 - 2010).
He is selected as the first ranked physics researcher in Iran in 2011. He created a large multidisciplinary research group in 2012 called NEST (NanoEnergy-Surface-Thin films) (https://nest.sharif.edu).
The activity of the group mainly focuses on surface processes using 2D/1D/0D nanostructures and hierarchical heterostructures.
He is selected as the “Chair of Surface & Interface Sciences” by Iran National Science Foundation in 2016 and promoted to “Distinguished Professor” in the SUT in 2017. His research interests focus mainly on role of surfaces and interfaces in photocatalysis/electrocatalysis for clean energy production and environmental remediation.
He has served as editorial board member of “Vacuum”, “Research in Chemical Intermediates” and “ACS ES&T Engineering” Journals since 2008, 2020 and 2024, respectively. He has delivered more than 140 invited talks in international conferences and published more than 180 peer-reviewed research articles, review papers and book chapters that all cited over 9400 times with H = 52 (Google Scholar).
Oct. 22, 2024 ( Week 08)
Nicholas Glavin
Air Force Research Laboratory in Ohio, U. S
2D Electronic Materials: Opportunities for Sensing, Low Power Computing, and Advanced Integration📹
Host: Mario Hofmann
Time: 2:20 pm - 4:20 pm
Place: Room 104, CCMS-New Phys. building
Abstract
Two-dimensional (2D) materials represent an exciting opportunity to create novel functionalities for next generation micro- and nanoelectronics.
In this talk, strategies and processes to enable high throughput design and customization of 2D materials which enable multifunctional properties is presented.
These techniques include using h-BN for heterogeneous integration of gallium nitride films, rapid laser-manufacturing approaches to tune structure/property relationships for efficient device design, and heterostructures for low power electronics.
By tackling foundational issues regarding synthesis, processing, and characterization while harnessing the diverse design space of these emerging materials, advanced technologies integrated into everyday life will be possible in the not-so-distant future.
Brief Bio
Dr. Nicholas Glavin, a Senior Materials Engineer at the Materials and Manufacturing Directorate within the Air Force Research Laboratory (AFRL), brings more than 14 years of experience and contributions to nanomaterials science and engineering.
Holding a PhD in Mechanical Engineering from Purdue University and a background in Chemical Engineering from the University of Dayton, he is recognized for his expertise in nanomaterial synthesis, processing and relevant applications.
His research area focuses on the synthesis and applications of electronic materials, including 2D materials, nitride, transition metal dichalcogenides, and their heterostructures for various electronic and sensing devices. His research has earned him awards including the Air Force Research Laboratory Early Career Award and the American Vacuum Society Paul Holloway Young Investigator Award.
Oct. 29, 2024 ( Week 09)
Chien-Jung Lo
Department of Physics and Center for Complex Systems, National Central University, Jhongli 32001, Taiwan
Bacterial flagellar motor: from a molecular machine to a biosensor
Host: Po-Ti Chang
Time: 2:20 pm - 4:20 pm
Place: Room 104, CCMS-New Phys. building
Abstract
Bacterial Flagellar Motor (BFM) is one of nature’s rare rotary molecular machines.
It enables bacterial swimming and is the key part of the bacterial chemotactic network, one of the best-studied chemical signaling networks in biology, allowing bacteria to direct their movement according to the chemical environment.
The network can sense down to nanomolar concentrations of specific chemicals on the time scale of seconds.
BFMs’ rotational speed is linearly proportional to the electrochemical gradients of either proton or sodium driving ions, while the chemotactic network regulates its direction. Recently, it has been discovered that BFM is also a mechanosensor.
Given these properties, I will present my research from the understanding of BFM functional mechanisms to the application as a multimodal biosensor. The BFMs are powerful tools for characterizing and studying the external environment, bacterial physiology, and single molecular motor biophysics.
Brief Bio
Education
2003 – 2007 DPhil in Physics, University of Oxford, UK
1998 – 2000 MSc in Physics, National Central University, Taiwan
1994 – 1998 BS in Physics, National Central University, Taiwan
Working Experience
2018 – Present Professor, Physics, National Central University, Taiwan
2021 – 2024 Chair, Center for Complex Systems, NCU, Taiwan
2022 – 2024 Associate Chair, Physics, National Central University, Taiwan
2022 – 2024 Distinguished Professor NCU
2021 – 2023 Secretary-general, PBBP Division, Taiwan Physics Society
2020 – 2022 Deputy Editor-in-chief of Physics Bimonthly
2014 – 2022 Editor of Physics Bimonthly
2018 – 2019 Associate Chair, Physics, National Central University, Taiwan
2014 – 2018 Associate Professor, Physics, National Central University, Taiwan
2009 – 2014 Assistant Professor, Physics, National Central University, Taiwan
Honors and Awards
2022 MOST Outstanding Research Award
2022-24 NCU Distinguished Professor
2021 NCU Outstanding Teaching Award
2018-21 NCU Outstanding Research Award
2016 Academia Sinica Thematic Project
2015 HFSP Research Award
2013 NCU Teaching Award
2009 NCU Young PI Award
2007 Diawa-Adrain Prize (UK group member)
2003 Overseas Research Students Award Scheme (ORSAS), UK
2003 Swire Scholarship for the DPhil study in University College, Oxford
2001 The MSc Thesis Award of Physics Society of R.O.C.
2000 The Honor Membership of The Phi Tau Phi Scholastic Honor Society of R.O.C.
Nov. 05, 2024 ( Week 10)
Shang-Fan Lee
Institute of Physics, Academia Sinica
Spintronics in low dimensional magnets
Host: Po-Ti Chang
Time: 2:20 pm - 4:20 pm
Place: Room 104, CCMS-New Phys. building
Abstract
Antiferromagnetic (AFM) materials have traditionally been regarded as insensitive to magnetic perturbations, serving mainly as supporting materials in spin valve cells.
However, recent studies have highlighted the potential advantages of AFM materials, including ultrafast spin dynamics and zero stray fields. We investigate whether spin-orbit torque (SOT) generated by heavy metals can modify the orientation of the AFM Néel vector or thermal contribution dominates.
Based on a theoretical approach of the Néel vector dynamic equation of motion derived from the LLG equation, we extend the analytical model to the case with uniaxial anisotropy. Experiments were conducted using NiPS3/Pt heterostructures.
NiPS3, a variant of transition metal dichalcogenides, is a two-dimensional van der Waals material in which Ni ions form a honeycomb lattice, with the a-axis aligned along the zigzag direction.
The spins of the Ni ions are collinear and lie close to the a-axis, forming ferromagnetic spin chains with antiferromagnetic inter-chain alignment. To investigate these samples, we employed second harmonic Hall voltage measurements using a lock-in amplifier.
Photoluminescence (PL) emission from NiPS3 has been reported to be spin-correlated, enabling optical determination of the Néel vector. The mechanism behind the ultra-sharp polarized PL signals in NiPS3, which do not appear in FePS3, MnPS3, remains to be clarified.
Brief Bio
Prof. Shang-Fan Lee received his PhD in Physics from Michigan State University, USA; went on as a postdoc in university of Paris-Sud, France; then came back to Institute of Physics, Academia Sinica.
His contributions in the course of spintronics development include the current perpendicular to plane giant magnetoresistance (CPP GMR) effect, which quantitatively determined the relative contributions between bulk and interface effects.
More recently, his works involved spin waves in submicron magnetic structures, the Anomalous Hall Effect (AHE) in Topological Insulator/Ferrimagnet heterostructure, and the properties in van der Waals low dimensional materials.
Nov. 12, 2024 ( Week 11)
Yuan-Hann Chang
Institute of Physics, Academia Sinica
Latest results from the AMS experiment
Host: Po-Ti Chang
Time: 2:20 pm - 4:20 pm
Place: Room 104, CCMS-New Phys. building
Abstract
AMS is a space-borne magnetic spectrometer on board of the International Space Station. AMS measures the spectra of cosmic-ray electrons, positrons, protons, and antiprotons, as well as the nuclei from helium to sulfur, with percent level precision.
The spectra show new features that are not expected prior to AMS. In this talk, I will show the latest spectra measurements and the time-dependance of the fluxes. In particular, the special features seen in the time-variation of antiproton fluxes, which is carried out recently by our group, will be presented.
Implications of these measurements are briefly discussed. In addition to the data analysis, AMS collaboration is carrying out a major upgrade to increase the acceptance by 300 percent. The design and construction status of the upgrade are also described.
Brief Bio
Yuan-Hann Chang obtained his bachelor degree from NTU physics department in 1983, and PhD degree from MIT in 1990.
He is currently a distinguished research fellow in the Institute of Physics, Academia Sinica. His research field is particle physics experiment.
During the past 10 years, his main research activities include the AMS experiment, which measures the cosmic ray spectra in space, and the TASEH experiment, which searches for Axion Darkmatter with a haloscope detector.
Nov. 19, 2024 ( Week 12)
Chih-Sung Chuu
Department of Physics, National Tsing Hua University, Taiwan
Optical quantum computing and communication
Host: Po-Ti Chang
Time: 2:20 pm - 4:20 pm
Place: Room 104, CCMS-New Phys. building
Abstract
Quantum information processing enables denser encoding, safer transmission, and faster processing of information by harnessing quantum mechanical effects.
In this talk, I will report the first demonstrations of optical quantum computer and quantum communication in Taiwan.
Brief Bio
Education
2001.9–2006.12, Ph.D. in Physics, The University of Texas at Austin, USA.
1995.9–1999.6, B.S. in Physics, National Tsing Hua University, Taiwan.
Current position
2024.08–present, Professor, Department of Physics, National Tsing Hua University, Taiwan
Experience
2018.2–2024.7, Associate Professor, Department of Physics, National Tsing Hua University, Taiwan
2012.2–2018.1, Assistant Professor, Department of Physics, National Tsing Hua University, Taiwan
2012.6–2012.9, Visiting Scholar, Edward L. Ginzton Laboratory, Stanford University, USA
2008.8–2012.1, Postdoctoral research fellow, Edward L. Ginzton Laboratory, Stanford University, USA.
2007.2–2008.7, Postdoctoral research fellow, Institute of Physics, University of Heidelberg, Germany.
Nov. 26, 2024 ( Week 13)
Eric Akkermans
Host: Ming-Feng Shih
Time: 2:20 pm - 4:20 pm
Place: Room 104, CCMS-New Phys. building
Abstract
Brief Bio
Dec. 03, 2024 ( Week 14)
Host: Ssu-Yen Huang
Time: 2:20 pm - 4:20 pm
Place: Room 104, CCMS-New Phys. building
Abstract
Brief Bio
Dec. 10, 2024 ( Week 15)
Dam Thanh Son
Host: Pei-Ming Ho
Time: 2:20 pm - 4:20 pm
Place: Room 104, CCMS-New Phys. building
Abstract
Brief Bio
Dec. 17, 2024 ( Week 16 )
Final
Joint Colloquia 
