Dali Cheng

All Publications

• Non-Abelian lattice gauge fields in photonic synthetic frequency dimensions. Nature Cheng, D., Wang, K., Roques-Carmes, C., Lustig, E., Long, O. Y., Wang, H., Fan, S. 2025; 637 (8044): 52-56

  Abstract

  Non-Abelian gauge fields1 provide a conceptual framework to describe particles having spins, underlying many phenomena in electrodynamics, condensed-matter physics2,3 and particle physics4,5. Lattice models6 of non-Abelian gauge fields allow us to understand their physical implications in extended systems. The theoretical importance of non-Abelian lattice gauge fields motivates their experimental synthesis and explorations7-9. Photons are fundamental particles for which artificial gauge fields can be synthesized10-30, yet the demonstration of non-Abelian lattice gauge fields for photons has not been achieved. Here we demonstrate SU(2) lattice gauge fields for photons in the synthetic frequency dimensions31,32, a playground to study lattice physics in a scalable and programmable way. In our lattice model, we theoretically observe that homogeneous non-Abelian lattice gauge potentials induce Dirac cones at time-reversal-invariant momenta in the Brillouin zone. We experimentally confirm the presence of non-Abelian lattice gauge fields by two signatures: linear band crossings at the Dirac cones, and the associated direction reversal of eigenstate trajectories. We further demonstrate a non-Abelian scalar lattice gauge potential that lifts the degeneracies of the Dirac cones. Our results highlight the implications of non-Abelian lattice gauge fields in topological physics, and provide a starting point for demonstrations of emerging non-Abelian physics in the photonic synthetic dimensions. Our results may also benefit photonic technologies by providing controls of photon spins and pseudo-spins in topologically non-trivial ways33.

  View details for DOI 10.1038/s41586-024-08259-2

  View details for PubMedID 39743600

  View details for PubMedCentralID 6635576

• Numerical and theoretical study of eigenenergy braids in two-dimensional photonic crystals PHYSICAL REVIEW B Zhong, J., Wojcik, C. C., Cheng, D., Fan, S. 2023; 108 (19)

  View details for DOI 10.1103/PhysRevB.108.195413

  View details for Web of Science ID 001112330600012

• Multi-dimensional band structure spectroscopy in the synthetic frequency dimension. Light, science & applications Cheng, D., Lustig, E., Wang, K., Fan, S. 2023; 12 (1): 158

  Abstract

  The concept of synthetic dimensions in photonics provides a versatile platform in exploring multi-dimensional physics. Many of these physics are characterized by band structures in more than one dimensions. Existing efforts on band structure measurements in the photonic synthetic frequency dimension however are limited to either one-dimensional Brillouin zones or one-dimensional subsets of multi-dimensional Brillouin zones. Here we theoretically propose and experimentally demonstrate a method to fully measure multi-dimensional band structures in the synthetic frequency dimension. We use a single photonic resonator under dynamical modulation to create a multi-dimensional synthetic frequency lattice. We show that the band structure of such a lattice over the entire multi-dimensional Brillouin zone can be measured by introducing a gauge potential into the lattice Hamiltonian. Using this method, we perform experimental measurements of two-dimensional band structures of a Hermitian and a non-Hermitian Hamiltonian. The measurements reveal some of the general properties of point-gap topology of the non-Hermitian Hamiltonian in more than one dimensions. Our results demonstrate experimental capabilities to fully characterize high-dimensional physical phenomena in the photonic synthetic frequency dimension.

  View details for DOI 10.1038/s41377-023-01196-1

  View details for PubMedID 37369684

  View details for PubMedCentralID PMC10300075

• Artificial Non-Abelian Lattice Gauge Fields for Photons in the Synthetic Frequency Dimension. Physical review letters Cheng, D., Wang, K., Fan, S. 2023; 130 (8): 083601

  Abstract

  Non-Abelian gauge fields give rise to nontrivial topological physics. Here we develop a scheme to create an arbitrary SU(2) lattice gauge field for photons in the synthetic frequency dimension using an array of dynamically modulated ring resonators. The photon polarization is taken as the spin basis to implement the matrix-valued gauge fields. Using a non-Abelian generalization of the Harper-Hofstadter Hamiltonian as a specific example, we show that the measurement of the steady-state photon amplitudes inside the resonators can reveal the band structures of the Hamiltonian, which show signatures of the underlying non-Abelian gauge field. These results provide opportunities to explore novel topological phenomena associated with non-Abelian lattice gauge fields in photonic systems.

  View details for DOI 10.1103/PhysRevLett.130.083601

  View details for PubMedID 36898123

• Optical Neural Network Architecture for Deep Learning with Temporal Synthetic Dimension CHINESE PHYSICS LETTERS Peng, B., Yan, S., Cheng, D., Yu, D., Liu, Z., Yakovlev, V. V., Yuan, L., Chen, X. 2023; 40 (3)

  View details for DOI 10.1088/0256-307X/40/3/034201

  View details for Web of Science ID 000936427500001

• Technologically feasible quasi-edge states and topological Bloch oscillation in the synthetic space OPTICS EXPRESS Wu, X., Wang, L., Li, G., Cheng, D., Yu, D., Zheng, Y., Yakovlev, V. V., Yuan, L., Chen, X. 2022; 30 (14): 24924-24935

  View details for DOI 10.1364/OE.462156

  View details for Web of Science ID 000821326000058

• Truncation-dependent PT phase transition for the edge states of a two-dimensional non-Hermitian system PHYSICAL REVIEW B Cheng, D., Peng, B., Xiao, M., Chen, X., Yuan, L., Fan, S. 2022; 105 (20)

  View details for DOI 10.1103/PhysRevB.105.L201105

  View details for Web of Science ID 000809495000002

• Low temperature open-air plasma deposition of amorphous tin oxide for perovskite solar cells THIN SOLID FILMS Zhao, O., Ding, Y., Cheng, D., Zhang, J., Hilt, F., Rolston, N., Jiang, G., Dauskardt, R. H. 2021; 730

  View details for DOI 10.1016/j.tsf.2021.138708

  View details for Web of Science ID 000657685100001

• Arbitrary synthetic dimensions via multiboson dynamics on a one-dimensional lattice PHYSICAL REVIEW RESEARCH Cheng, D., Peng, B., Wang, D., Chen, X., Yuan, L., Fan, S. 2021; 3 (3)

  View details for DOI 10.1103/PhysRevResearch.3.033069

  View details for Web of Science ID 000674634400006