Ning Xi 西宁

Ph.D at Renmin University

Condensed Matter Theory

BIOGRAPHY

    Mainly study on the numerical simulation of strongly correlated electron systems and new algorithms on quantum many-body physics, especially the tensor-network algorithms on frustrated spin systems and quasi-1D systems.

    I am seeking a postdoc position in condensed matter theory, quantum computing, or other relevant fields.

Contact Me

RESEARCH INTERESTS

Including but not limited to

  • Numerical study on strongly correlated electron systems
    • Quantum criticality and emergent phenomena
    • Exotic quantum phases and transitions in frustrated spin systems
    • Dynamic properties of quantum spin systems in low dimensions
    • Optimal solutions of nonlinear self-consistent or variational equations
    • Quantum entanglement and universality

  • Theoretical analysis of novel experiments
    • Numerical simulation of novel experiments on quantum magnets
    • Construction of effective microscopic models
    • Parameter estimation and model validation based on experimental results
    • Mean-field understanding and effective mapping of novel experiments

  • Developing new algorithms on quantum many-body physics
    • New tensor-network algorithms on two-dimensional spin systems
    • New algorithms on searching global optima or optimum parameters
    • New algorithms based on mature projects or packages in engineering
    • Other relevant algorithms on frustrated systems, fermion systems, or concerned systems

SKILLS

  • Infinite tensor-network algorithms on ground states of 2D quantum spin systems
    • Projected entangled simplex state (PESS) construction of frustrated spin systems
    • Infinite time-evolution algorithms, including SU, CU, and FU
    • Variational optimization of infinite tensor network states
    • Contracting the infinite networks by CTMRG and boundary MPS
    • Unique techniques on PESS construction

  • Time-evolution algorithms on quasi-1D quantum spin systems
    • Ground-state properties based on MPS
    • Dynamical properties based on real-time-evolution algorithms
    • Thermodynamic properties based on MPO

  • Optimization algorithms and fitting skills
    • Optimal solutions of nonlinear equations
    • Model parameters’ fitting based on experimental results
    • Fitting of critical exponents and behaviors

  • Basic skills for Ph.D students in the area of condensed matter theory
    • Basic mean-field approximation
    • Basic transformations or mapping
    • Basic critical scaling theory and dimensional analysis
    • Basic symmetry analysis of Hamiltonian, Lagrangian, and experimental materials

  • Coding & programming
    • Skilled in MATLAB and Julia
    • Acquainted with Python, Fortran, Mathematica, and C language

EDUCATION

  • Doctor of Science | Theoretical physics - Renmin University of China

    Advisors: Rong Yu 俞榕 & Z. Y. Xie 谢志远

  • Bachelor of Science | Optical information science and technology- Hebei University

PUBLICATIONS

  1. Ning Xi, Hongyu Chen, Z. Y. Xie, and Rong Yu, First-order transition between the plaquette valence bond solid and antiferromagnetic phases of the Shastry-Sutherland model, Under review, arXiv:2111.07368
  2. Ning Xi, and Rong Yu, Dynamical signatures of deconfined quantum critical points in one dimension, Chinese Phys. B
  3. Ning Xi, and Rong Yu, Emergent O(4) symmetry at an one-dimensional deconfined quantum tricritical point, Under review, arXiv.2202.12543
  4. Ning Xi, Xiao Wang, Jianda Wu, and Rong Yu, Robust evidence for emergent E8 spectra in the CoNb2O6, In Preparation
  5. Yuchen Fan, Ning Xi, Changle Liu, Rong Yu, and Bruce Normand, Criticality and quantum critical end point in the fully frustrated bilayer Heisenberg antiferromagnetic model under a magnetic field, In Preparation
  6. Yi Cui, Haiyuan Zou, Ning Xi, Zhangzhen He, Y. X. Yang, L. Shu, G. H. Zhang, Z. Hu, T. Chen, Rong Yu, Jianda Wu, and Weiqiang Yu, Quantum Criticality of the Ising-like Screw Chain Antiferromagnet SrCo2V2O8 in a Transverse Magnetic Field, Phys. Rev. Lett. 123, 067203(2019)

PRESENTATIONS

HONORS AND AWARDS