Parity-Induced Thermalization Gap in Disordered Ring Lattices

• Published in: Physical review letters Vol. 122; no. 1; p. 013903
• Main Authors: Wang, Yao, Gao, Jun, Pang, Xiao-Ling, Jiao, Zhi-Qiang, Tang, Hao, Chen, Yuan, Qiao, Lu-Feng, Gao, Zhen-Wei, Dou, Jian-Peng, Yang, Ai-Lin, Jin, Xian-Min
• Format: Journal Article
• Language: English
• Published: United States 11.01.2019
• ISSN: 1079-7114
• DOI: 10.1103/PhysRevLett.122.013903

The gaps separating two different states widely exist in various physical systems: from the electrons in periodic lattices to the analogs in photonic, phononic, plasmonic systems, and even quasicrystals. Recently, a thermalization gap, an inaccessible range of photon statistics, was proposed for light in disordered structures [Nat. Phys. 11, 930 (2015)NPAHAX1745-247310.1038/nphys3482], which is intrinsically induced by the disorder-immune chiral symmetry and can be reflected by the photon statistics. The lattice topology was further identified as a decisive role in determining the photon statistics when the chiral symmetry is satisfied. Being very distinct from one-dimensional lattices, the photon statistics in ring lattices are dictated by its parity, i.e., odd or even sited. Here, we for the first time experimentally observe a parity-induced thermalization gap in strongly disordered ring photonic structures. In a limited scale, though the light tends to be localized, we are still able to find clear evidence of the parity-dependent disorder-immune chiral symmetry and the resulting thermalization gap by measuring photon statistics, while strong disorder-induced Anderson localization overwhelms such a phenomenon in larger-scale structures. Our results shed new light on the relation among symmetry, disorder, and localization, and may inspire new resources and artificial devices for information processing and quantum control on a photonic chip.