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Past Events
Spring 2023 Physics Colloquium
| Schedule: | From February 1 to April 26, 2023 (Every other Wednesday) February 1, 2023 (Wed), 10:00 a.m. February 15, 2023 (Wed) 4:00 p.m. March 15, 2023 (Wed) 5:00 p.m. March 29, 2023 (Wed) 5:00 p.m. April 12, 2023 (Wed) 10:00 a.m. April 26, 2023 (Wed) 5:00 p.m. |
From the fall semester of 2021, the colloquium will happen on every other Wednesday either in the morning or afternoon. The detailed schedule and talk information are as below.
For inquiries or suggestions of future speakers, please contact the colloquium working group (Dr. Jane Lixin Dai, Dr. Tran Trung Luu, Dr. Yanjun Tu, Dr. Chenjie Wang, and Dr. Shizhong Zhang).
Coherence, entanglement, and clock: from emergent phenomena to fundamental physics
(Joint Colloquium of the Department of Physics and the Hong Kong Institute of Quantum Science and Technology)
Speaker: Prof. Jun YE
Affiliation: JILA, National Institute of Standards and Technology and University of Colorado Boulder
Date: February 1, 2023 (Wednesday)
Time: 10:00 a.m.
Zoom Link: https://bit.ly/3HHlgqB
Meeting ID: 916 0248 2628
Password: 2859
Poster: Download
Abstract:
Precise quantum state engineering, many-body physics, and innovative laser technology are revolutionizing the performance of atomic clocks and metrology, providing opportunities to explore emerging phenomena and probe fundamental physics. Recent advances include measurement of gravitation time dilation across a few hundred micrometers, and employment of quantum entanglement for clock comparison.
Key References:
1. A Fermi-degenerate three-dimensional optical lattice clock
2. Imaging Optical Frequencies with 100 μHz Precision and 1.1 μm Resolution
The future of high-energy physics with colliders
Speaker: Dr. Michelangelo MANGANO
Affiliation: CERN
Date: February 15, 2023 (Wednesday)
Time: 4:00 p.m.
Zoom Link: https://bit.ly/3JHhf6X
Meeting ID: 910 1760 9238
Password: 2859
Poster: Download
Abstract:
Particle physics is engaged in a worldwide effort to deepen our understanding of key issues, from the origin of dark matter and neutrino masses, to the dynamics of electroweak symmetry breaking and of non-perturbative strong interactions. A wide landscape of facilities and experiments, in the laboratory, in the sky and underground, in addition to theoretical work, are mobilized in these efforts. In this landscape, collider experiments play a special role, and, with the current success of the LHC, are consolidating their unique potential to continue driving the future progress.
Key References:
1. Future Circular Colliders succeeding the LHC
2. PLHC at 10: the physics legacy
3. Physics Briefing Book: Input for the European Strategy for Particle Physics Update 2020
Understanding the strongly correlated features of the electronic structure of twisted bilayer graphene from the pseudo Landau level picture
(Joint Colloquium of the Department of Physics and the Hong Kong Institute of Quantum Science and Technology)
Speaker: Prof. Xi DAI
Affiliation: The Hong Kong University of Science and Technology
Date: March 1, 2023 (Wednesday) March 8, 2023 (Wednesday)
Time: 5:00 p.m.
Venue: KKLG102, LG1/F, K.K. Leung Building, The University of Hong Kong CYPP3, LG1, Chong Yuet Ming Physics Building, HKU
Poster: Download
Abstract:
In the present colloquium, I will introduce how the flat bands in the magic angle twisted bilayer graphene (MATBG) can be understood from the zeroth Landau levels under the twisting generated pseudo magnetic field. These pseudo Landau level wave functions are almost the exact Eigen solutions of the real space Hamiltonian around the AA stacking center and can be further viewed as the analog of the “atomic core level” states in the band structure calculations for the ordinary crystals. In addition, we can use the pseudo zeroth Landau level (PZLL) and the “orthogonalised plane waves” (OPW) made from the PZLL as the two types of basis functions to efficiently reconstruct the entire Moire band structure. Using these PZLL and OPW basis functions, we can describe both the localised and itinerant components in the Moire bands of MATBG and map the MATBG to a “heavy fermion” like system, which can be used to study the orbital magnetism, topology and strongly correlation physics in MATBG.
Key References:
1. Jianpeng Liu, Junwei Liu, and Xi Dai, PHYSICAL REVIEW B 99, 155415 (2019)
2. Hao Shi and Xi Dai, PHYSICAL REVIEW B 106, 245129 (2022)
Hacking Stars to Better Understand our Universe
(Joint colloquium of the Faculty of Science and the Department of Physics)
Speaker: Dr. Hakeem OLUSEYI, PhD
Affiliation: Astrophysicist and Former Space Science Education Manager for NASA; Faculty Research Fellow at the Princeton Space Plasma Laboratory; Visiting Robinson Professor at George Mason University; President of the National Society of Black Physicists
Date: March 15, 2023 (Wednesday)
Time: 5:00 p.m.
Venue: KB223, 2/F, Knowles Building, The University of Hong Kong
Registration is Required: https://bit.ly/3SseKYm
Poster: https://www.scifac.hku.hk/events/hacking-stars-to-better-understand-our-universe
Abstract:
Dr Hakeem Oluseyi, the author of the critically acclaimed memoir, “A Quantum Life: My Unlikely Journey from the Streets to the Stars”, is an internationally-recognised astrophysicist, science TV personality, and global education advocate with a long, distinguished career in academia and scientific research. Most recently, he was stationed at NASA Headquarters, where he served as an Astrophysicist and Space Science Education Lead for NASA's Science Mission Directorate.
In this talk, he will discuss his scientific research based on ‘hacking stars’, which allows him to develop innovative new technologies and deepen our understanding of the universe. He will also talk about his work leveraging techniques for interpreting electromagnetic radiation, laboratory plasma physics, computational modeling, machine learning, and high-performance computing.
Gravitational waves from tidal disruption events
Speaker: Dr. Elena ROSSI
Affiliation: Leiden Observatory
Date: March 29, 2023 (Wednesday)
Time: 5:00 p.m.
Zoom Link: https://bit.ly/3ldo724
Meeting ID: 984 4647 6440
Password: 2859
Poster: Download
Abstract:
A tidal disruption event (TDE) involves a star tidally disrupted by a massive black hole: such a seemingly simple event results in an observationally rich --potentially multimessanger -phenomena, where many aspects are still poorly understood. In this talk I will present the multi messenger aspects of TDEs and then focus on their gravitational wave emission and prospects for detection with future space based missions.
Key References:
1. https://ui.adsabs.harvard.edu/abs/2020MNRAS.498..507T/abstract
2. https://ui.adsabs.harvard.edu/abs/2019MNRAS.489..699T/abstract
Topological heat transport
Speaker: Prof. Dima FELDMAN
Affiliation: Brown University
Date: April 12, 2023 (Wednesday)
Time: 10:00 a.m.
Zoom Link: https://bit.ly/40hIjyC
Meeting ID: 969 7547 2947
Password: 2859
Poster: Download
Abstract:
The quantization of the electrical conductance is the defining property of the quantum Hall effect. Quantized electrical transport is often used for the classification of topological states of matter, but different topological orders may exhibit the same electrical conductance. Some topological systems, including Kitaev magnets, do not conduct electricity. At the same time, heat can flow in any material. We will review quantized thermal conductance in two-dimensional topological materials as well as recent experimental and theoretical advances in probing topological orders with heat transport.
Key References:
[1] K. K. W. Ma and D. E. Feldman, Thermal equilibration on the edges of topological liquids, Phys. Rev. Lett. 125, 016801 (2020).
[2] Z. Wei, N. Batra, V. F. Mitrović, and D. E. Feldman, Thermal interferometry of anyons, Phys. Rev. B 107, 104406 (2023).
A journey through time...varying materials
Speaker: Dr. Simon HORSLEY
Affiliation: University of Exeter
Date: April 26, 2023 (Wednesday)
Time: 5:00 p.m.
Zoom Link: https://bit.ly/3KzkKes
Meeting ID: 941 4010 6401
Password: 2859
Poster: Download
Abstract:
Physics students often leave university believing that classical physics is complete, and all new discoveries will be made in quantum mechanics. This is a shame.
In classical electromagnetism or acoustics for instance, there is a colossal space of possible materials that is largely unexplored. I will begin this talk by asking the question: if we could make all these different materials, what could we do? Invisibility cloaking, negative refractive indices, analogue gravity, 'synthetic gauge fields' for light, and some recent advances in antenna engineering have all come from asking this question.
Moreover, this is not just idle speculation: metamaterials - sub wavelength structured composites with 'designer' bulk properties - allow us to explore these exotic materials in the laboratory. Until very recently the focus was on static composites where their effective properties do not change in time. In the second half of the talk I will review new theory and experimental developments with time varying metamaterials, showing their counter intuitive effect on propagating waves, and their connection with space-time geometry.
Key References:
[1] E. Galiffi et. al. "Photonics of Time-varying media" Advanced Photonics 4, 014002 (2022).
[2] R. Tirole et. al. "Double-slit time diffraction at optical frequencies" Nat. Phys. https://doi.org/10.1038/s41567-023-01993-w (2023).
[3] V. Pacheco-Pena and N. Engheta, "Temporal Aiming", Light Sci. Appl. 9 129 (2020).
[4] S. A. R. Horsley, E. Galiffi, and Y.-T. Wang, "Eigenpulses of dispersive time-varying media" arxiv:2208.11778 (2022) (accepted in PRL)
[5] S. A. R. Horsley and J. B. Pendry, "Time-varying gratings model Hawking radiation" arxiv:2302.04066 (2023)