I am a research fellow in Center for Computational Quantum Physics (CCQ), the Flatiron institute. My research searches for the emergent physical laws that drives the collective behaviors in real materials, ultracold atomic gases and quantum circuits. For this purpose, I have been leading a team to develop modern theoretical and numerical framework for quantum many-body physics. I am a core member of the Simons Collaboration on the Many Electron Problem, contributing to both research areas Monte Carlo and Real Materials. My long-term research goals include:

1. Develop a modern quantum field theory of the many electron problem in real materials, then use the field theory to design next-gen ab-initio methods for electronic structure calculations.

2. Model the multi-particle scattering in semiconductors, superconductors and many other systems, understand how they drive electronic instabilities and other exotic phenomena. Explore possible experimental probes to measure the angle-resolved multi-particle scattering amplitudes.

3. Searching for the interdisciplinary quantum many-body problems in quantum emulation and quantum computation.

Solving the above problem calls for a new toolbox. For this purpose, I’m leading a team to develop a general-puposed numerical effective field theory (NEFT) framework.

📝 Publications

• Entanglement and Charge-Sharpening Transitions in U(1) Symmetric Monitored Quantum Circuits, Utkarsh Agrawal, Aidan Zabalo, Kun Chen, Justin Wilson, Andrew Potter, Jed Pixley, Sarang Gopalakrishnan, and Romain Vasseur. Phy. Rev. X 12, 041002 (2022)

• Superconductivity in the Uniform Electron Gas: Irrelevance of Kohn-Luttinger Mechanism, Xiansheng Cai, Tao Wang, Nikolay Prokof’ev*, Boris Svistunov*, and Kun Chen*, Phys. Rev. B 106, L220502(2022)

• On the Origin of Coulomb Pseudopotential: Two Wrongs Make a “Right”, Tao Wang, Xiansheng Cai, Kun Chen*, Nikolay Prokof’ev*, and Boris Svistunov*, ArXiv 2207.05238(2022)

• Dynamic response of the electron gas: Towards the exact exchange-correlation kernel, James LeBlanc, Kun Chen, Kristjan Haule, Nikolay Prokof’ev, Igor Tupitsyn*, Phys. Rev. Lett. 129, 246401(2022), EDITORS’ SUGGESTION

• Exchange-Correlation Effect in the Charge Response of a Warm Dense Electron Gas, Pengcheng Hou, Bao Wang, Kristjan Haule, Youjin Deng, and Kun Chen*, Phys. Rev. B 106, L081126(2022)

• Discrete Lehmann representation of imaginary time Green’s functions, Jason Kaye*, Kun Chen and Olivier Parcollet, Phys. Rev. B 105, 235115(2022)

• libdlr: Efficient imaginary time calculations using the discrete Lehmann representation, J. Kaye, K. Chen, and H. Strand, Comput. Phys. Commun. 280, 108458(2022)

• Single-particle excitations in the uniform electron gas by diagrammatic Monte Carlo, Kristjan Haule*, and Kun Chen, Sci. Rep. 12, 2294 (2022)

• Quantitative electron-electron interaction using local field factors from quantum Monte Carlo calculations, Carl Kukkonen, and Kun Chen, Phys. Rev. B 104.195142 (2021)

• Fermionic Sign Structure of High-order Feynman diagrams in a Many-fermion System, Baozong Wang, Pengcheng Hou, Youjin Deng, Kristjan Haule, Kun Chen. Phys. Rev. B 103,115141 (2021)

• Finite-size Scaling of $O(n)$ Systems at the Upper Critical Dimensionality, Jian-Ping Lv*, Wanwan Xu, Yanan Sun, Kun Chen*, Youjin Deng*. National Science Review: nwaa212 (2021)

• Quantum-to-classical correspondence in two-dimensional Heisenberg models, Tao Wang, Xiansheng Cai, Kun Chen, Nikolay Prokof’ev, Boris Svistunov. Phys. Rev. B 101, 035132(2020)

• A combined variational and diagrammatic quantum Monte Carlo approach to the many-electron problem, Kun Chen*, and Kristjan Haule*, Nature Communications 10.1(2019)

• Even-odd Effect of an Spin-$S$ Impurity Coupled to a Quantum Critical System, Kun Chen, and Yashar Komijani. Phys. Rev. B 100, 094514 (2019)

• Quantized Magnetic Flux and the Magneto-halon Effect in a Critical Superconductor, Kun Chen, and Boris Svistunov. Phys. Rev. B 98, 140503 (2018). RAPID COMMUNICATIONS, EDITORS’ SUGGESTION

• The halon: a quasiparticle featuring critical charge fractionalization, Kun Chen, Yuan Huang, Youjin Deng, and Boris Svistunov, Phys. Rev. B 98, 214516 (2018)

• Trapping collapse: Infinite number of repulsive bosons trapped by a generic short-range potential, Kun Chen, Nikolay Prokof’ev, and Boris Svistunov, Phys. Rev. A 98, 041602 (2018). RAPID COMMUNICATIONS

• Trapping Centers at the Superfluid-Mott-insulator Criticality: Transition between Charge-quantized States, Yuan Huang, Kun Chen*, Youjin Deng, and Boris Svistounov. Phys. Rev. B 94, 220502 (2016). RAPID COMMUNICATIONS

• Spin-ice state of the quantum Heisenberg antiferromagnet on the pyrochlore lattice, Yuan Huang, Kun Chen}*, Youjin Deng*, Nikolay Prokof’ev, and Boris Svistounov, Phys. Rev. Lett. 116, 177203 (2016).

• Massive Goldstone (Higgs) mode in two-dimensional ultracold atomic lattice systems, Longxiang Liu, Kun Chen}*, Youjin Deng*, Manuel Endres, Lode Pollet, and Nikolay Prokof’ev, Massive Goldstone, Phys. Rev. B 92, 174521 (2015). EDITORS’ SUGGESTION

• Higgs mode near superfluid-to-Mott-insulator transition studied by the quantum Monte Carlo method, Kun Chen*, and Youjin Deng, Acta Physica Sinica 64, 0180201 (2015). INVITED REVIEW

• Universal Conductivity in a Two-Dimensional Superfluid-to-Insulator Quantum Critical System, Kun Chen, Longxiang Liu, Youjin Deng*, Lode Pollet*, and Nikolay Prokof’ev*, Phys. Rev. Lett. 112, 030402 (2014). EDITORS’ SUGGESTION

• Two-dimensional Potts antiferromagnets with a phase transition at arbitrarily large q, Yuan Huang*, Kun Chen*, Youjin Deng*, Jesper L. Jacobsen*, Roman Koteck'y*, Jesus Salas*, Alan Sokal*, and Jan Swart*, , Phys. Rev. E 87, 012136 (2013).

• Deconfined Criticality Flow in the Heisenberg Model with Ring-Exchange Interactions, Kun Chen, Yuan Huang, Youjin Deng*, Anatoly Kuklov*, Nikolay Prokof’ev*, and Boris Svistunov*, Phys. Rev. Lett. 110, 185701 (2013).

• Universal Properties of the Higgs Resonance in (2+1)-Dimensional U(1) Critical Systems, Kun Chen, Longxiang Liu, Youjin Deng*, Lode Pollet*, and Nikolay Prokof’ev*, , Phys. Rev. Lett. 110, 170403 (2013).

💬 Invited Talks

• 2022.6, Mechanisms for Superconductivity Workshop (Flatiron, New York City), Renormalized Field Theory of the Electron Liquid

• 2022.5, 2022 Workshop on Recent Developments in Electronic Structure (ES22) (Columbia University, New York City), Picasso’s bull study and the renormalized theory of valence electrons

• 2021.3, APS March Meeting, The variational and diagrammatic quantum Monte Carlo approach to the many-electron problem.

• 2021.11, APS MAS Meeting, Electron-Electron Interaction in the Uniform Electron Gas.

• 2021.4, International Young Scholar Forum (Chinese Academy of Sciences, Beijing), Systematic Effective Field Theory Approach to the Many-electron Problem.

• 2020.10, International Conference on Computer Simulation in Physics and beyond (Moscow, Russia), Controlled Effective Field Theory Approach to the Electron Liquid”.

• 2019.7, Workshop on Diagrammatic Monte-Carlo (Flatiron, New York City)，Diagrammatic Monte Carlo RG approach to Condensed Matter Field Theory.

• 2018.11, CSRC Workshop on Computational Approach to Correlated Systems (CSRC, Beijing)，Cluster Diagrammatic Monte Carlo Method for Interacting Electrons.

• 2018.10，International Workshop on Precision Many Body Physics (Wilczek Quantum Center)， The Halon: A Quasiparticle Featuring Critical Charge Fractionalization.

• 2018.4, The 2nd International Workshop on Critical Behavior in Lattice Models (Anqing Normal University)， Halon: A quasiparticle featuring critical charge fractionalization.

• 2015.1, MURI meeting (Rice University, Houston) Hunting for the Higgs Mode in Ultracold Atoms in Optical Lattices.

• 2013.4, International Workshop on Critical Behavior in Lattice Models (Beijing)， Deconfined Criticality Flow in the Heisenberg Model with Ring-exchange Interactions.

• 2014.6, Workshop on Higgs Modes in the Condensed Matter and Quantum Gases (Kyoto University)，Universal Quantum Dynamics near the Two-dimensional Superfluid-to-Insulator Transition.

• 2014.5, Workshop on Precision Many-body Physics of Strongly correlated Quantum Matter (KITPC, Beijing)，Universal Quantum Dynamics near the Two-dimensional Superfluid-to-Insulator Quantum Critical System.

🎖 Honors and Awards

• 2019 Kandula Sastry Thesis Award for an outstanding Ph.D. thesis in Physics
• 2015 Chinese Academy of Sciences President’s Special Award (highest honor for Ph.D. candidates in China)
• 2015 Outstanding Graduate Student Scholar of Innovation Center for Quantum Information and Quantum Frontiers (Special Award)
• 2013, 2015 China National Scholarship for Graduate Students
• 2011 The First Professor Hangsheng Wu Memorial Award link
• 2010 Guo Moruo Scholarship (highest honor for B.S. candidates in the university)

📖 Educations

• June 2020 - now, Flatiron Research Fellow, Center for Computational Quantum Physics, Flatiron Institue, New York City, USA
• Sep 2017 - Jun 2020, Simons Postdoctoral Fellow, Rutgers University, New Jersey, USA
• Sep 2012 - May 2018, PhD, University of Massachusetts Amherst, Massachusetts, USA
• Sep 2011 - Oct 2016, PhD, National Laboratory for Physical Sciences at the Microscale, Hefei, China
• Sep 2007 - Jun 2011, B.S. University of Science and Technology of China, Hefei, China