Ang Chen
· Associate Professor, EECS – Computer Science and EngineeringAssociate Director, Systems LabVerifiedUniversity of Michigan · Computer Science and Engineering
Active 2005–2025
Research topics
- Particle physics
- Computer Science
- Physics
- Nuclear physics
- Algorithm
- Quantum mechanics
- Simulation
- Database
- Operating system
- Mathematics
- Engineering
- Statistics
- Computational science
- Aerospace engineering
Selected publications
Canadian Quantum Ecosystem: Lessons From the 5th Workshop on Quantum Computing Entrepreneurship
IEEE Engineering Management Review · 2025-08-25
articleSenior authorThis article is part of a series exploring the unique characteristics and challenges of managing technology teams in emerging fields, with a particular focus on quantum computing [1-5]. The series delves into the experiences of entrepreneurs, researchers, and organizations at the forefront of the quantum revolution, offering insights into team management, innovation, and ecosystem development. Canada's vibrant quantum computing ecosystem is undergoing rapid expansion driven by a combination of government support, world-class academic institutions, and a thriving entrepreneurial community. The 5th Workshop on Quantum Computing Entrepreneurship, held during IEEE Quantum Week 2024, was organized by volunteers from the IEEE Technology & Engineering Management Society (TEMS), IEEE Entrepreneurship, and the Institut quantique. This workshop explored the key pillars of Canada's quantum ecosystem, showcasing the experiences of those driving the quantum revolution. These pillars encompass national and regional organizations that foster ecosystem growth, quantum accelerators that facilitate technology transfer from academia to industry, and the startups driving commercialization. Beyond offering valuable insights into the Canadian quantum ecosystem, this article also highlights fundamental components essential to any quantum ecosystem, given the current maturity of the technology. Readers involved in policy, entrepreneurship, or technology management can apply these lessons to foster quantum ecosystems in their own regions or organizations.
Diagnostics · 2025-03-31
articleOpen accessBackground/Objectives: Fluorescein angiography (FA) is essential for diagnosing and managing diabetic retinopathy (DR) and other retinal vascular diseases and has recently demonstrated potential as a quantitative tool for disease staging. The advent of ultra-widefield (UWF) FA, allowing visualization of the peripheral retina, enhances this potential. Retinal hypoperfusion is a critical risk factor for proliferative DR, yet quantifying it reliably remains a challenge. Methods: This study evaluates the efficacy of the Michigan grid method, a software-based grading system, in detecting retinal hypoperfusion compared to the traditional freehand method. Retinal UWF fluorescein angiograms were obtained from 50 patients, including 10 with healthy retinae and 40 with non-proliferative DR. Two independent, masked graders quantified hypoperfusion in each image using two methods: freehand annotation and a new Michigan grid method. Results: Using the Michigan grid method, Grader 1 identified more ungradable segments, while Grader 2 identified more perfused and nonperfused segments. Cohen’s weighted kappa indicated substantial agreement, which was slightly higher for the entire retina (0.711) compared to the central retinal area (0.686). The Michigan grid method shows comparable or slightly improved inter-rater reliability compared to the freehand method. Conclusions: This study demonstrates a new Michigan grid method for the evaluation of FA for hypoperfusion while highlighting ongoing challenges in achieving consistent and objective retinal nonperfusion assessment, underscoring the need for further refinement and the potential integration of automated approaches.
Multi-modal Swarm Intelligence for Secure UAV Missions
2025-10-21
book-chapterOpen accessSenior authorAbstract Unmanned Aerial Vehicles (UAVs) have found wide use in various tasks, but developing swarm intelligence for intrusion detection is far from easy. In this project, we propose to leverage recent advances in large multimodal models (LMMs) that can fuse multiple data sources for secure missions. Our project will fine-tune and deploy LMMs of varying sizes to the edge/fog UAVs, combining data sources such as sensory inputs (e.g., camera, IMU) as well as internal operational data (e.g., syscall logs). This will enable real-time detection and response system to thwart threats with swarm-wide coordination, addressing Challenge #2 outlined by the GENZERO workshop. Moreover, we aim to perform hardware-in-the-loop tests, with real devices, data, and scenarios, leveraging University of Michigan’s M-Air 10,000 sq ft, four-story, testing facility. We envision that the final outcome will be an integrated system and demo validated in M-Air, achieving Technology Readiness Level 4 (TRL4).
Annals of the Rheumatic Diseases · 2024-06-01
articleDeep Blue (University of Michigan) · 2023-01-01
articleOpen access1st authorCorrespondingWe report on the search for new Higgs-like particles with SM-like scalar couplings produced in pp collisions with a mass in the range of 66 – 110 GeV/c2 and decay- ing to two photons. The search is conducted in the pp collision data collected by the ATLAS detector during the Run 2 data-taking period of the LHC. Using an integrated luminosity of 139.5 fb−1 at a pp center-of-mass energy of √s = 13 TeV recorded in 2015 – 2018, we develop and apply techniques in this data to find and identify narrow width resonances predicted by theories with an extended Higgs sec- tor. No significant signals are observed, and the cross section times branching ratio for a SM-like Higgs-like scalar decaying to two photons is limited to be less than the experimental sensitivity of this search, approximately 50fb over the mass range of 66 – 110 GeV/c2. A less restrictive model-independent search that focuses on only the dominant scalar production mode similarly finds no signals, and the cross section times branching ratio is limited to less than approximately 70 fb in the same mass range.
Physical review. C · 2023-09-06 · 12 citations
articleOpen accessEvidence for a flavor asymmetry between the $\overline{u}$ and $\overline{d}$ quark distributions in the proton has been found in deep-inelastic scattering and Drell-Yan experiments. The pronounced dependence of this flavor asymmetry on $x$ (fraction of nucleon momentum carried by partons) observed in the Fermilab E866 Drell-Yan experiment suggested a drop of the $\overline{d}(x)/\overline{u}(x)$ ratio in the $x>0.15$ region. We report results from the SeaQuest Fermilab E906 experiment with improved statistical precision for $\overline{d}(x)/\overline{u}(x)$ in the large $x$ region up to $x=0.45$ using the 120 GeV proton beam. Two different methods for extracting the Drell-Yan cross section ratios, ${\ensuremath{\sigma}}^{pd}/2{\ensuremath{\sigma}}^{pp}$, from the SeaQuest data give consistent results. The $\overline{d}(x)/\overline{u}(x)$ ratios and the $\overline{d}(x)\ensuremath{-}\overline{u}(x)$ differences are deduced from these cross section ratios for $0.13<x<0.45$. The SeaQuest and E866/NuSea $\overline{d}(x)/\overline{u}(x)$ ratios are in good agreement for the $x\ensuremath{\lesssim}0.25$ region. The new SeaQuest data, however, show that $\overline{d}(x)$ continues to be greater than $\overline{u}(x)$ up to the highest $x$ value ($x=0.45$). The new results on $\overline{d}(x)/\overline{u}(x)$ and $\overline{d}(x)\ensuremath{-}\overline{u}(x)$ are compared with various parton distribution functions and theoretical calculations.
AtlFast3: The Next Generation of Fast Simulation in ATLAS
Computing and Software for Big Science · 2022 · 106 citations
- Computer Science
- Computer Science
- Computational science
Abstract The ATLAS experiment at the Large Hadron Collider has a broad physics programme ranging from precision measurements to direct searches for new particles and new interactions, requiring ever larger and ever more accurate datasets of simulated Monte Carlo events. Detector simulation with Geant4 is accurate but requires significant CPU resources. Over the past decade, ATLAS has developed and utilized tools that replace the most CPU-intensive component of the simulation—the calorimeter shower simulation—with faster simulation methods. Here, AtlFast3, the next generation of high-accuracy fast simulation in ATLAS, is introduced. AtlFast3 combines parameterized approaches with machine-learning techniques and is deployed to meet current and future computing challenges, and simulation needs of the ATLAS experiment. With highly accurate performance and significantly improved modelling of substructure within jets, AtlFast3 can simulate large numbers of events for a wide range of physics processes.
A detailed map of Higgs boson interactions by the ATLAS experiment ten years after the discovery
Nature · 2022 · 371 citations
- Physics
- Particle physics
- Nuclear physics
. Since then, more than 30 times as many Higgs bosons have been recorded by the ATLAS experiment, enabling much more precise measurements and new tests of the theory. Here, on the basis of this larger dataset, we combine an unprecedented number of production and decay processes of the Higgs boson to scrutinize its interactions with elementary particles. Interactions with gluons, photons, and W and Z bosons-the carriers of the strong, electromagnetic and weak forces-are studied in detail. Interactions with three third-generation matter particles (bottom (b) and top (t) quarks, and tau leptons (τ)) are well measured and indications of interactions with a second-generation particle (muons, μ) are emerging. These tests reveal that the Higgs boson discovered ten years ago is remarkably consistent with the predictions of the theory and provide stringent constraints on many models of new phenomena beyond the standard model.
Journal of Instrumentation · 2022-10-01 · 2 citations
articleOpen accessAbstract This paper reports on the design and construction of infrastructure and test stations for small-diameter monitored drift tube (sMDT) assembly and testing at the University of Michigan (UM) to prepare for the ATLAS Muon Spectrometer upgrade for the high-luminosity program of the Large Hadron Collider. Procedures of the tube assembly and quality assurance and control (QA/QC) tests are described in detail. More than 99% of the tubes meet the tube QA/QC specifications based on 2100 tubes built at UM. The UM test stations are also used for QA/QC testing on the tubes constructed at Michigan State University. These tubes are being used to construct the sMDT chambers which will replace the current MDT chambers of the barrel inner station of the Muon Spectrometer.
The European Physical Journal C · 2021 · 100 citations
- Computer Science
- Physics
- Algorithm
Abstract A search for chargino–neutralino pair production in three-lepton final states with missing transverse momentum is presented. The study is based on a dataset of $$\sqrt{s} = 13$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> <mml:mo>=</mml:mo> <mml:mn>13</mml:mn> </mml:mrow> </mml:math> TeV pp collisions recorded with the ATLAS detector at the LHC, corresponding to an integrated luminosity of 139 $$\hbox {fb}^{-1}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mtext>fb</mml:mtext> <mml:mrow> <mml:mo>-</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:math> . No significant excess relative to the Standard Model predictions is found in data. The results are interpreted in simplified models of supersymmetry, and statistically combined with results from a previous ATLAS search for compressed spectra in two-lepton final states. Various scenarios for the production and decay of charginos ( $${\tilde{\chi }}^\pm _1$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mrow> <mml:mover> <mml:mi>χ</mml:mi> <mml:mo>~</mml:mo> </mml:mover> </mml:mrow> <mml:mn>1</mml:mn> <mml:mo>±</mml:mo> </mml:msubsup> </mml:math> ) and neutralinos ( $${\tilde{\chi }}^0_2$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mrow> <mml:mover> <mml:mi>χ</mml:mi> <mml:mo>~</mml:mo> </mml:mover> </mml:mrow> <mml:mn>2</mml:mn> <mml:mn>0</mml:mn> </mml:msubsup> </mml:math> ) are considered. For pure higgsino $${\tilde{\chi }}^\pm _1{\tilde{\chi }}^0_2$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msubsup> <mml:mrow> <mml:mover> <mml:mi>χ</mml:mi> <mml:mo>~</mml:mo> </mml:mover> </mml:mrow> <mml:mn>1</mml:mn> <mml:mo>±</mml:mo> </mml:msubsup> <mml:msubsup> <mml:mrow> <mml:mover> <mml:mi>χ</mml:mi> <mml:mo>~</mml:mo> </mml:mover> </mml:mrow> <mml:mn>2</mml:mn> <mml:mn>0</mml:mn> </mml:msubsup> </mml:mrow> </mml:math> pair-production scenarios, exclusion limits at 95% confidence level are set on $${\tilde{\chi }}^0_2$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mrow> <mml:mover> <mml:mi>χ</mml:mi> <mml:mo>~</mml:mo> </mml:mover> </mml:mrow> <mml:mn>2</mml:mn> <mml:mn>0</mml:mn> </mml:msubsup> </mml:math> masses up to 210 GeV. Limits are also set for pure wino $${\tilde{\chi }}^\pm _1{\tilde{\chi }}^0_2$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msubsup> <mml:mrow> <mml:mover> <mml:mi>χ</mml:mi> <mml:mo>~</mml:mo> </mml:mover> </mml:mrow> <mml:mn>1</mml:mn> <mml:mo>±</mml:mo> </mml:msubsup> <mml:msubsup> <mml:mrow> <mml:mover> <mml:mi>χ</mml:mi> <mml:mo>~</mml:mo> </mml:mover> </mml:mrow> <mml:mn>2</mml:mn> <mml:mn>0</mml:mn> </mml:msubsup> </mml:mrow> </mml:math> pair production, on $${\tilde{\chi }}^0_2$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mrow> <mml:mover> <mml:mi>χ</mml:mi> <mml:mo>~</mml:mo> </mml:mover> </mml:mrow> <mml:mn>2</mml:mn> <mml:mn>0</mml:mn> </mml:msubsup> </mml:math> masses up to 640 GeV for decays via on-shell W and Z bosons, up to 300 GeV for decays via off-shell W and Z bosons, and up to 190 GeV for decays via W and Standard Model Higgs bosons.
Frequent coauthors
- 1121 shared
L. Xu
Tsinghua University
- 972 shared
T. Beau
Consejo Nacional de Investigaciones Científicas y Técnicas
- 943 shared
J. Jia
- 933 shared
H. Bachacou
Institut de Recherche sur les Lois Fondamentales de l'Univers
- 928 shared
L. Schoeffel
CEA Paris-Saclay
- 928 shared
F. Déliot
CEA Paris-Saclay
- 926 shared
A. Formica
CEA Paris-Saclay
- 925 shared
M. Saimpert
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
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