Hi there, I'm

Lida Xu —
curious about light.

A physics PhD candidate at the Joint Quantum Institute, UMD. I build photonic chips that bend light in unusual ways — and try to make those tricks robust enough to be actually useful.

Hafezi Lab · UMD he/him
See my publications → Download CV
Lida just started graduate school
Lida in his final PhD year
2021

Lida was just starting his physics PhD.

2026

Lida is in his final PhD year. Five years older.
Same hairline. Don't ask me how.

Publications

Selected papers.

Three papers that mark where I've spent the most time. The full list — preprints, in-prep work, and media coverage — lives on the publications page.

Multi-timescale frequency-phase matching
Science · Nov 2025 · Co-first author

Multi-timescale frequency-phase matching for high-yield nonlinear photonics

Helping nonlinear photonic chips work the same way twice — a step toward wafer-scale reliability.

Read the paper →
Science Advances cover, September 2025
Science Advances · Jun 2025 · First author

On-chip multi-timescale spatiotemporal optical synchronization

Two frequency combs locking together across wildly different timescales (1 THz and 4 GHz) on the same topological chip.

Read the paper →
Observation of topological frequency combs
Science · Jun 2024 · Co-first author

Observation of topological frequency combs

The first experimental demo of frequency combs that inherit topological protection and nested structure from their lattice. Where a lot of my current work begins.

Read the paper →

See the full publication list →

A little about me

Physicist. Engineer. Tinkerer.

The basics

CurrentlyPhysics PhD candidate
WhereHafezi Lab, UMD
Before thatBS Physics, Nanjing U.
FieldTopological & nonlinear photonics
LanguagesEnglish · 中文

I think of myself as a hybrid — part physicist, part engineer, and somewhere between an experimentalist and a theorist.

My work sits at the intersection of topological photonics, nonlinear optics, and frequency combs — using the geometry of photonic lattices to make optical "rulers" that are stable, broadband, and chip-scale.

Fundamental science is cool, and I really want it to do something with it — that's the part that gets me out of bed.

— Lida

The path so far

Education & experience.

2021 — present Current

PhD candidate, Physics

University of Maryland, College Park · Joint Quantum Institute

Advised by Prof. Mohammad Hafezi. Working on integrated nonlinear topological photonics — building photonic chips that turn ideas from condensed matter physics into useful devices.

2020 — 2021

Research assistant

Southern University of Science and Technology (SUSTech), Shenzhen

Gap year due to COVID between undergrad and PhD spent doing research and figuring out where to go next.

2016 — 2020

BS, Physics

Nanjing University

Where it all started — my first taste of doing physics seriously.

2010 — 2016

Junior & senior high school

Jiangsu Tianyi High School, Wuxi

Six formative years in a classroom, working out which questions felt worth asking.

What I work on

Research directions.

Three intersecting threads I keep pulling on. Each is its own field — together, they're how I think about turning fundamental physics into devices.

01

Topological photonics

Designing photonic lattices whose band structure inherits topological invariants from condensed matter — so light flows along boundaries that disorder can't disrupt.

edge modes artificial gauge fields quantum Hall effects
Read more →
02

Integrated nonlinear photonics

Pushing high optical intensities into chip-scale waveguides until they generate frequency combs, harmonics, and entirely new colors of light — reliably, at wafer scale.

Kerr combs microresonators harmonic generation
Read more →
03

Photonic computing

Asking whether the same lattices can do useful computation — using light's natural parallelism and topology's robustness to build a different kind of processor for AI workloads.

reservoir computing optical neural networks TOPAI
Read more →
Inventions

Patents filed.

Four provisional US patents (filed 2025), all with equal share among co-inventors. These come out of joint work with the Hafezi Lab and collaborators at NIST.

Provisional · 2025

Systems of ultrabroadband multimodal artificial gauge fields

Inventors: L. Xu, M. J. Mehrabad, S. Sarkar, A. Padhye, M. Hafezi
Provisional · 2025

Nested frequency and phase matching

Inventors: M. J. Mehrabad, L. Xu, G. Moille, K. Srinivasan, M. Hafezi
Provisional · 2025

Quantum optical metamorphosis

Inventors: M. J. Mehrabad, A. Parhizkar, L. Xu, M. Hafezi
Provisional · 2025

TOPAI: Topological photonics architectures for optical computing and AI

Inventors: M. J. Mehrabad, L. Xu, S. Sarkar, Z. Y. Wei, M. Hafezi
Recent & upcoming talks

Where I've been sharing this.

CLEO 2026 talk
CLEO 2026 · May 18, 2026

Frequency comb realization of the integer quantum Hall model

First realization of the photonic nonlinear IQH model.

Event details →
PQE 2026 invited talk
PQE 2026 · Jan 5, 2026 · Invited

Integrated nonlinear topological photonics

Recent works on integrated nonlinear topological photonics.

Event details →
Recognition

Awards & honors.

A few highlights along the way — and one reminder that I am, in fact, capable of running.

2026
NSF I-Corps™ Teams Award · Entrepreneurial Lead
National Science Foundation · View certificate↗
🏆
2026
UMD Invention of the Year · Winner
University of Maryland · TOPAI: Topological Photonics Architecture for Optical Computing & AI · View plaque↗
💡
2021
Ralph Myers and Friends of Physics Award · Honorable Mention
University of Maryland, Department of Physics
🎖️
2018–19
Elite Program Scholarship
School of Physics, Nanjing University
📚
2016
High School Soccer League · Silver Medalist
Wuxi City — proof I have done at least one non-physics thing
⚽
When I'm not in the lab

Things that also matter to me.

🤝

The people I work with

I've been lucky to work with brilliant collaborators across UMD, NIST, and beyond. Science is a team sport, and the team makes it worth doing.

🌉

Bridging worlds

Theory and experiment, physics and engineering, fundamental and applied — I like the messy in-between. Sharp boundaries are usually wrong.

🛠️

Building tools

I write a lot of simulation software for our group. There's something satisfying about a tool that other people actually use.

📚

Translating science

I like explaining hard ideas in simple language. If a Nobel-Prize idea can't be told to a curious friend, we haven't finished understanding it yet.

Featured · Science communication

I make a physics video series on Bilibili.

A five-part deep dive into Paul Dirac and the strange world of antimatter, in Mandarin. Outreach is its own craft — and I love practicing it.

Watch the series →

I'm always up for a good conversation — about photonics, collaborations, or anything else.

📧 Email 🔬 Lab page 📚 Google Scholar 💻 GitHub 📄 CV