12/9 The Road Not Taken:
Decadal Mission on Higgs/Flavor

Time: 1:20pm~3:10pm, December 9 (Thursday)
Title: The Road Not Taken: Decadal Mission on Higgs/Flavor

Speaker: Prof. George Wei-Shu Hou
(Department of Physics, National Taiwan University)
Place: Science Building III 1F SC157

11/25 Entanglement, non-unitary conformal field theories, and non-Hermitian quantum systems

Time: 1:20pm~3:10pm, November 25 (Thursday)
Title: Entanglement, non-unitary conformal field theories, and non-Hermitian quantum systems

Speaker: Prof. Po-Yau Chang
(Department of Physics, National Tsing Hua University)
Place: Science Building III 1F SC157

Abstract:

Entanglement is a powerful tool to diagnose many-body quantum systems. The triumph examples are the critical systems where the low energy property can be described by conformal field theories (CFTs). The central charge which uniquely characterizes the CFT can be perfectly extracted from the entanglement entropy. However, the entanglement properties for non-unitary CFTs are not well understood. Moreover, the microscopic models of fermionic systems which can be described by non-unitary CFTs have not been explored. In this colloquium, I would like to demonstrate several non-Hermitian fermionic systems which can be described by non-unitary CFTs, and show their entanglement properties can be correctly obtained by our proposed generic entanglement entropy.

11/18 Simulate quantum transport by quench dynamics using matrix product state

Time: 1:20pm~3:10pm, November 18 (Thursday)
Title: Simulate quantum transport by quench dynamics using matrix product state
Speaker: Prof. Chia-Min Chung
(Department of Physics, National Sun Yat-Sen University)
Google Meet Link: http://meet.google.com/xhy-yotv-wax

Abstract: Studying the transport properties of a nanostructure is a key tool in understanding and developing quantum devices. In this work we develop a method to simulate quantum transport in interacting systems using matrix product state. In particular we develop a method to simulate the current in a superconducting chain with charging energy, which is close related to a Majorana chain system. We benchmark our result in both a quantum dot system and a Majorana chain.

10/21 Early Stage of Star Formation

Time: 1:20pm~3:10pm, October 21 (Thursday)
Title: Early Stage of Star Formation
Speaker: Prof. Shih-Ping Lai
(Department of Physics, National Tsing Hua University)
Google Meet Link: http://meet.google.com/xhy-yotv-wax

10/14 Correlated dynamics in quantum link models

Time: 1:20pm~3:10pm, October 14 (Thursday)
Title: Correlated dynamics in quantum link models
Speaker: Prof. Yi-Ping Huang
(Department of Physics, National Tsing Hua University)
Google Meet Link: http://meet.google.com/xhy-yotv-wax

Abstract: Constrained systems, such as frustrated magnets, are crucial to form non-trivial entanglement. However, real-time dynamics for those systems are relatively unexplored. In this talk, I will discuss the quench dynamics of a particular type of model: the 2D quantum link model. I will discuss the dynamics within a specific gauge sector where the dynamical quantum phase transition is observed in this 2D correlated constrained system. I will also discuss the influence of the initial wave function. We found the disorder-free localization phenomena when we prepared the initial state as a superpositi on of di fferent superselection sectors.

10/7 Transfer Matrix Revolutions

Time: 1:20pm~3:10pm, October 7 (Thursday)
Title: Transfer Matrix Revolutions
Speaker: Prof. Ying-Jer Kao
(Department of Physics, National Taiwan University)
Google Meet Link: http://meet.google.com/xhy-yotv-wax

 

3/25 STM/STS Studies of Layered Topological Materials

Time: 1:20pm, March 25 (Thursday)
Title: STM/STS Studies of Layered Topological Materials
Speaker: Chun-Liang Lin
(Electrophysics department, National Yang Ming Chiao Tung University )

Place: Science Building III 1F SC157

12/24 The First Images of a Black Hole and General Relativistic Magnetohydrodynamical (GRMHD) Accretion/Jet : achievements and challenges

Time: 1:20pm, December 24 (Thursday)
Title: The First Images of a Black Hole and General Relativistic Magnetohydrodynamical (GRMHD) Accretion/Jet : achievements and challenges
Speaker: Prof. Hung-Yi Pu
(Department of Physics, National Taiwan Normal University)

Place: Science Building III 1F SC110

12/17 The emergence of collective modes, ecological collapse and directed percolation at the laminar-turbulent transition

Time: 1:20pm, December 17 (Thursday)
Title: The emergence of collective modes, ecological collapse and directed percolation at the laminar-turbulent transition
Speaker: Dr. Hong-Yan Shih
(Institute of Physics, Academia Sinica)

Place: Science Building III 1F SC110

Abstract: 

How a laminar flow becomes turbulence has been an unsolved problem for more than a century and is important in various industrial applications. Recently precise measurements in pipe flow experiments showed non-trivial spatiotemporal complexity at the onset of turbulence where lifetime and splitting time of metastable turbulence do not diverge asymptotically as would have been expected in a sharp transition.
Based on numerical evidence from the hydrodynamics equations, we discovered the surprising fact that the fluid behavior at the transition is governed by the emergent predator-prey dynamics of the important long-wavelength mode, leading to the mathematical prediction that the laminar-turbulent transition is analogous to an ecosystem on the edge of extinction. This prediction demonstrates that the laminar-turbulent transition is a non-equilibrium phase transition in the directed percolation universality class, and provides a unified picture of transition to turbulence emerging in systems ranging from turbulent convection to magnetohydrodynamics.

Reference:
[1] Hong-Yan Shih, Tsung-Lin Hsieh and Nigel Goldenfeld, Nature Physics 12, 245 (2016)
[2] https://www.nature.com/collections/rxsztdqblr

12/10 Observation of an Unusual Upward-going Cosmic-ray-like Event in the Third Flight of ANITA

Time: 1:20pm, December 10 (Thursday)

Title: Observation of an Unusual Upward-going Cosmic-ray-like Event in the Third Flight of ANITA

Speaker: Prof. TsungChe Liu
(Electrophysics Department, National Chiao Tung University)

Place: Science Building III 1F SC110

Abstract:

We report on an upward traveling, radio-detected cosmic-ray-like impulsive event with characteristics closely matching an extensive air shower. This event,
observed in the third flight of the Antarctic Impulsive Transient Antenna (ANITA), a NASA-sponsored long-duration balloon payload, is consistent with a similar event reported in a previous flight.
These events may be produced by the atmospheric decay of an upward-propagating τ-lepton produced by a ντ interaction, although their relatively steep arrival angles create tension with the standard model (SM) neutrino cross section.
Each of the two events have a posteriori background estimates of <∼ 10^{−2} events.
If these are generated by τ-lepton decay, then either the charged-current ντ cross section is suppressed at EeV energies, or the events arise at moments
when the peak flux of a transient neutrino source was much larger than the typical expected cosmogenic background neutrinos.

https://arxiv.org/pdf/1803.05088.pdf

未解微中子之謎：質量來源、超乎模型預測的高能量