CTCP Seminar: “Deep Boundary Perturbations at a Quantum Critical Point” by Dr. Shang LIU | Wednesday, March 19, 2025, 3:30pm KKLG101

We explore an unconventional class of problems in the study of (quantum) critical
phenomena, termed “deep boundary criticality”. Traditionally, critical systems are analyzed with two types of perturbations: those uniformly distributed throughout the bulk, which can significantly alter the bulk criticality by triggering a nontrivial bulk renormalization group
flow, and those confined to a boundary or subdimensional defect, which affect only the boundary or defect condition. Here, we go beyond this paradigm by studying quantum critical systems with boundary perturbations that decay algebraically (following a power law) into the bulk. By continuously varying the decay exponent, such perturbations can
transition between having no effect on the bulk and strongly influencing bulk behavior. We investigate this regime using two prototypical models based on (1+1)D massless Dirac fermions. Through a combination of analytical and numerical approaches, we uncover exotic scaling laws in simple observables and observe qualitative changes in model behavior
as the decay exponent varies.

AQIS’25 25th Asian Quantum Information Science Conference | 4th -8th August 2025

QIS’25 Asian Quantum Information Science Conference

📅 Date: August 4 to August 8, 2025

📍Venue :

Grand Hall of the Lee Shau Kee Lecture Centre, Centennial Campus, the University of Hong Kong (HKU)
Hosted by:

Quantum Information and Computation Initiative (QICI) of the HKU School of Computing and Data Science

HK Institute of Quantum Science & Technology (HKIQST)

The AQIS’25 conference will focus on quantum information processing, communication, and cryptography, bridging the fields of quantum physics, computer science, mathematics, and information technologies. As the natural successor of EQIS’01-EQIS’05 and AQIS’06-AQIS’24, AQIS’25 will feature invited talks, selected oral and poster presentations, as well as other activities.

Conference Topics Include:

Quantum computation and simulation, algorithms, and complexity

Quantum information theory

Concepts, methods, and tools against decoherence

Quantum cryptography

Quantum communications experiments and theory

Quantum metrology

Quantum technologies (optics, NMR, solid state, etc.)

Quantum circuit, computer design, and architecture

Quantum programming languages and semantics

Important Dates:

Talk Submission Deadline: April 25, 2025

Poster-only Submission Deadline: May 16, 2025

Notification of Acceptance: May 30, 2025

Final Manuscript Deadline: June 30, 2025

Early Registration Deadline: June 30, 2025 (all deadlines are until 23:59 anywhere on Earth)

Invited Speakers:

Rotem Arnon-Friedman (Weizman Institute of Science)

Warit Asavanant (University of Tokyo)

Debbie Leung (University of Waterloo)

Chaoyang Lu (University of Science and Technology of China)

Chiao-Hsuan Wang (National Taiwan University)

Additional speakers to be announced…

Sponsors:

HKU School of Computing and Data Science

HK Institute of Quantum Science & Technology (HKIQST)

QICI

Join us at AQIS’25 for a deep dive into the exciting world of quantum information and computation!

The webpage address of AQIS 2025

http ://aqis-conf.org/2025/

APS March Meeting in Hong Kong | March 16–22, 2025

APS March Meeting in Hong Kong | March 16–22, 2025

The Physical Society of Hong Kong and the American Physical Society have agreed to hold a satellite conference in Hong Kong during the APS March Meeting from March 16 to 22, 2025. Some academic presentations made at the Hong Kong venue will be simultaneously broadcasted to the online platform of the APS March Meeting. Attendees can also view presentations from the APS online platform.

This conference provides a valuable platform for researchers who are unable to attend the meeting in the United States due to visa issues. It offers them the opportunity to showcase their research achievements and engage in academic exchanges with international collaborators.

Conference Organization:

Host Organization: Physical Society of Hong Kong

Co-organizer: American Physical Society | HK Institute of Quantum Science & Technology

Organizing Institutions: City University of Hong Kong | Qebula Mind Limited

Conference Chairs:

Professor Xunli Wang: Chair Professor, Department of Physics, City University of Hong Kong | Board Member and International Councilor, American Physical Society

Professor Zidan Wang: Chair Professor, Department of Physics, University of Hong Kong | Chairman of the Council, Physical Society of Hong Kong

Professor Bei Zeng: Professor, Department of Physics, Hong Kong University of Science and Technology | President, Physical Society of Hong Kong

Conference Committee Members:

Sunny Xin Wang

Xiao Li

Zhedong Zhang

Liang Dai

Conference Secretary:

Sunny Wang Xin: Department of Physics, City University of Hong Kong | Honorary Treasurer, Physical Society of Hong Kong

Jointly Organized by: APS, HK Physical Society of Hong Kong, HK Institute of Quantum Science & Technology, City University of Hong Kong, and Qebula Mind Limited

CTCP Seminar : “Quantum Spin Liquid as incompressible liquid of electrons” by Prof Yi ZHOU Monday, February 10, 2025, 5:00pm, LE8, Library Extension Building, HKU

An alternative to the “standard” quantum spin liquid model, which was constructed as a gauge theory, will be presented. This new framework is a Landau-type effective theory. We will explore both quasiparticle excitations and collective modes, along with their physical implications.

HKIQST Seminar “Nonequilibrium and nonlinear terahertz spectroscopy study on Higgs modes in conventional and unconventional superconductors” by Prof Nan-Lin WANG on Wednesday, January 15, 2025, 3:00 pm | CYPP3

We present recent progress in exploring the detection of superconducting collective modes in NbN, MgB2, and YBa2Cu3O6+x using innovative terahertz spectroscopy techniques. Transient Higgs oscillations and a higher-order nonlinear light-Higgs mode coupling effect were detected in NbN superconductors. In MgB2, the Higgs mode contribution from the dirty 3D pi-band and the Leggett mode contribution were identified. In YBCO samples, a beat pattern in the terahertz signal revealed a coupling effect between the Higgs mode and the mode developed below T*, indicating the pseudogap phase may be a distinct order, not a precursor to superconductivity. This strong coupling effect provides fresh insights into superconductivity and the pseudogap.