Quantum Phase

We investigate exotic quantum phases and phase transitions in strongly correlated systems, including supersolid phases, quantum spin liquids, and deconfined quantum criticality on geometrically frustrated lattices such as the triangular and kagome lattices. We also study the microscopic mechanisms of unconventional superconductivity, including d-wave pairing and spinon singlets in doped systems. Our work explores the interplay between topology, frustration, strong correlations, and quantum fluctuations using advanced numerical methods.

Quantum Frustration

We study exotic quantum phases emerging from geometric frustration on triangular and kagome lattices. Our research covers supersolid phases, quantum spin liquids, deconfined quantum criticality, and topological string excitations. Using large-scale quantum Monte Carlo simulations, we explore the interplay between frustration, topology, and strong correlations.

Publications:

  • Wei Xu and Xue-Feng Zhang*, "Interplay of unidirectional quantum strings in a kagome Rydberg atom array", Phys. Rev. B 113, L020408 (2026)
  • Zheng Zhou, Zheng Yan, Changle Liu*, Yan Chen, and Xue-Feng Zhang, "Quantum simulation of two-dimensional U(1) gauge theory in Rydberg atom arrays", Chinese Phys. Lett. 42, 053705 (2025)
  • Dong-Xu Liu, Zijian Xiong*, Yining Xu, and Xue-Feng Zhang*, "Deconfined quantum phase transition on the kagome lattice: Distinct velocities of spinon and string excitations", Phys. Rev. B 109, L140404 (2024).
  • Zheng Zhou, Changle Liu, Dong-Xu Liu, Zheng Yan*, Yan Chen*, and Xue-Feng Zhang*, "Quantum tricriticality of incommensurate phase induced by quantum strings in frustrated Ising magnetism", SciPost Phys. 14, 037 (2023)
  • Yan-Cheng Wang, Xue-Feng Zhang*, Frank Pollmann, Meng Cheng, and Zi Yang Meng*, "Quantum Spin Liquid with Even Ising Gauge Field Structure on Kagome Lattice", Phys. Rev. Lett. 121, 057202 (2018)
  • Xue-Feng Zhang, Yin-Chen He, Sebastian Eggert, Roderich Moessner, and Frank Pollmann, "Continuous Easy-Plane Deconfined Phase Transition on the Kagome Lattice", Phys. Rev. Lett. 120, 115702 (2018)
  • Xue-Feng Zhang*, Shi-Jie Hu*, Axel Pelster, and Sebastian Eggert, "Quantum Domain Walls Induce Incommensurate Supersolid Phase on the Anisotropic Triangular Lattice", Phys. Rev. Lett. 117, 193201 (2016)
  • Daniel Sellmann, Xue-Feng Zhang*, and Sebastian Eggert, "Phase diagram of the antiferromagnetic XXZ model on the triangular lattice", Phys. Rev. B 91, 081104(R) (2015)
  • Luca F. Tocchio, Claudius Gros, Xue-Feng Zhang, and Sebastian Eggert, "Phase diagram of the triangular extended Hubbard model", Phys. Rev. Lett. 113, 246405 (2014)
  • Xue-Feng Zhang and Sebastian Eggert, "Chiral Edge States and Fractional Charge Separation in a System of Interacting Bosons on a Kagome Lattice", Phys. Rev. Lett. 111, 147201 (2013)

High-Tc Superconductivity

We investigate the microscopic mechanisms of unconventional superconductivity in strongly correlated systems. Our recent work focuses on d-wave pairing mediated by quantum colored strings and the role of spinon singlets in hole-doped systems, providing insights into the pairing mechanism in partially-filled stripes. Most importantly, we introduce a new theoretical framework for understanding the interplay between quantum fluctuations and superconducting correlations--quantum colored strings model (QCSM).

Publications:

  • Ying Liang, Yi-Da Chu, Shi-Jie Hu*, and Xue-Feng Zhang*, "Microscopic nature of 4a0 × 4a0 plaquettes in stripe LDOS and 2a0 shift", arXiv:2603.25245
  • Jia-Long Wang, Shi-Jie Hu*, and Xue-Feng Zhang*, "Spinon Singlet: Microscopic Mechanism of d-Wave Pairing in a Partially-Filled Stripe", arXiv:2507.18892
  • Jia-Long Wang, Shi-Jie Hu*, and Xue-Feng Zhang*, "Spinon Singlet in Quantum Colored String: Origin of d-Wave Pairing in a Partially-Filled Stripe", arXiv:2412.04379
  • Jia-Long Wang, Shi-Jie Hu*, and Xue-Feng Zhang*, "Quantum colored strings in the hole-doped t-Jz model", Phys. Rev. B 111, 205121 (2025)

Cavity-QED

We explore quantum many-body phenomena in cavity-QED systems, including Rydberg polaritons, superradiant solids, and quantum phase transitions in Rydberg atom arrays coupled to optical cavities. Our work bridges strong correlations with light-matter interactions.

Publications:

  • Ying Liang, Bao-Yun Dong, Zi-Jian Xiong, and Xue-Feng Zhang*, "Frustrated Rydberg Atom Arrays Meet Cavity-QED: Emergence of the Superradiant Clock Phase", Phys. Rev. Lett. 136, 073602 (2026)
  • Gao-Qi An, Tao Wang*, and Xue-Feng Zhang, "Quantum phase transition of a two-dimensional Rydberg atom array in an optical cavity", Phys. Rev. B 106, 134506 (2022)
  • Yu-Yu Zhang*, Zi-Xiang Hu, Libin Fu, Hong-Gang Luo, Han Pu, and Xue-Feng Zhang*, "Quantum Phases in a Quantum Rabi Triangle", Phys. Rev. Lett. 127, 063602 (2021)
  • Xue-Feng Zhang, Qing Sun, Yu-Chuan Wen, Wu-Ming Liu, Sebastian Eggert, and An-Chun Ji, "Rydberg Polaritons in a Cavity: A Superradiant Solid", Phys. Rev. Lett. 110, 090402 (2013)
  • Bao-Yun Dong, Ying Liang, Stefano Chesi*, and Xue-Feng Zhang*, "Quantum phase transitions of the anisotropic Dicke-Ising model in driven Rydberg arrays", arXiv:2511.22230