Instability, symmetry, and topology/geometry

Yu-Ping Lin (林育平)

Senior Scientist - Quantum Chemistry

IonQ, Inc., USA

About Me

I am a Senior Scientist - Quantum Chemistry at IonQ, Inc.. Before joining the quantum computing industry, I was a Gordon and Betty Moore Postdoctoral Fellow at Department of Physics, University of California, Berkeley. I received my Ph.D. in Physics at University of Colorado Boulder, as well as M.S. in Physics and B.S. in Physics with Minor in Mathematics at National Taiwan University. See the CV page for more details about me!

This personal website is used only for my personal research in theoretical condensed matter physics.

Google Scholar

NASA ADS

GitHub

Research Expertise

As a theoretical quantum condensed matter physicist, I am interested in the nature of quantum materials and quantum many-body systems involving interaction, singular density of states, symmetry, topology/geometry, and/or nonequilibrium. I enjoy studying these systems with a balanced combination of theoretical modeling, analytic calculation, and numerical computation. My current research focuses on the interacting-electron phases in quantum materials and their ultrafast optical controls, as well as the topology and geometry in quantum materials. While in academia, I have worked on and been continuously interested in various research topics, including but not limited to:

Correlated phases in quantum materials:
- Materials at Van Hove singularity (VHS): Kagome metals and moiré systems
- Flat-band materials: Kagome and pyrochlore metals
- Unconventional superconductivity
Alternagmetism:
- Odd-parity altermagnetism from sublattice currents
Sublattice imbalance in quantum materials:
- Sublattice polarization: Understanding and systematic search on common lattices
Nonequilibrium dynamics in quantum materials:
- Ultrafast optical control of kagome metals: Dynamics in pump-probe setup
Band topology and geometry:
- Band geometry: Position-momentum-duality interpretation of quantum metric
- Band topology: Symmetry protection, edge and corner states, etc
Magnetoresistance in semimetals
Disordered quantum spin systems

See the Research page if you are interested in more details, and the Publications page for a complete list of my work!

CMTKit: Condensed Matter Theory Toolkit

Since I started my postdoctoral stint at UC Berkeley, a significant portion of my research has been based on numerical computations of quantum many-body systems. To manage the codes for different projects harmoniously, I started to establish and maintain my own python library, CMTKit, for versatile computations in theoretical condensed matter physics. CMTKit is a scientific Python library for quantum materials and many-body lattice models. It is built upon fundamental scientific Python libraries, such as numpy, scipy, and sparse for matrix and tensor computations, as well as matplotlib (2D) and mayavi (3D) for graphics. This library has supported my broad exploration into various quantum many-body systems for diverse 1D, 2D, and 3D quantum materials.

The main features of my library include:

Public repository on GitHub
Wide applicability on arbitrary 1D to 3D lattices and Fermi-Hubbard models [Paper]
Computation of band structures and superconducting/spin/charge ordered states:
- Mean field: Hartree-Fock(-Bogoliubov) theory [Paper]
- Dynamics: Time-dependent Hartree-Fock(-Bogoliubov) theory [Paper]
- Beyond mean field: Functional renormalization group (RG) [Reference]
- Classical Monte Carlo: Spin systems
Tensor network methods for strongly correlated quantum systems:
- Essential tools for tensor networks, including a direct contraction of arbitrary diagrams
- Multiscale entanglement renormalization ansatz (MERA) [Reference]
3D visualization of lattices and superconducting/spin/charge ordered states [Paper]

Demo: Altermagnetism on a honeycomb lattice

This figure of altermagnetism (arXiv:2503.09602) demonstrates the computational and graphical capabilities in my package. The upper figures show (left) the Haldane model with charge currents on the honeycomb lattice, as well as (right) its altermagnetic ground state under repulsive interaction obtained by the Hartree-Fock theory. The lower figures show (left) the band structures with spin splitting and (right) the splitting energy map of the lower two occupied bands in the Brillouin zone.

Recent talk

Check out my talk at a Rice zoom seminar series for some of my research topics!

Recent News

<June 2026> Our work "Odd-parity altermagnetism through sublattice currents: From Haldane-Hubbard model to general bipartite lattices" with Marc has been accepted by Physical Review Letters as an Editors' Suggestion!
<August 2025> I have started a new position as Senior Scientist - Quantum Chemistry at IonQ!
<March 2025> I have given a talk "Sublattice imbalance in quantum materials: Sublattice polarization and odd-parity altermagnetism" at APS March Meeting, American Physical Society, Anaheim, CA, USA!
<February 2025> I have given a talk "Correlated phases and ultrafast optical control in kagome quantum materials" at Physics Colloquium, University of Texas at Dallas, Richardson, TX, USA!
<November 2024> Our work "Pair-breaking scattering interference as a mechanism for superconducting gap modulation" with Zhi-Qiang and Dung-Hai has been posted by Physical Review B!
<November 2024> Our work "Ultrafast optical control of charge orders in kagome metals" with Vidya and Joel has been posted on arXiv!
<July 2024> Our work "Complex magnetic and spatial symmetry breaking from correlations in kagome flat bands" with Chunxiao and Joel has been posted on Physical Review B as a Letter!
<July 2024> I have given a talk "Electronic phase diagrams in frustration-induced flat bands" at GLAM Seminar, Stanford University, Stanford, CA, USA!
<June 2024> Our work "Sublattice polarization from destructive interference on common lattices" has been posted on arXiv!
<April 2024> Our work "Geometric semimetals and their simulation in synthetic matter" with Gian has been posted on Physical Review B as a Letter!

See more news here!