2016/09/30 by Hoi Chun Po, Lukasz Fidkowski, Takahiro Morimoto +2 · 3 citations
Physics and Astronomy · #Boson #Chiral symmetry #Cold Atom Physics and Bose-Einstein Condensates #Entropy (arrow of time) #Floquet theory #Logarithm #Parity (physics) #Quantum many-body systems #Topological Materials and Phenomena #Topology (electrical circuits) #cond-mat.dis-nn #cond-mat.quant-gas #cond-mat.str-el #quant-ph
paper · pdf · doi:10.1103/physrevx.6.041070
published as Phys. Rev. X 6, 041070 (2016) · (18+11) pages; (9+2) figures. v2: Minor changes, references updated. v3: References updated, additional discussion on interacting fermions
openalex created_date 2016/09/16 · arxiv created 2016/10/17 · openalex publication_date 2016/12/30 · arxiv updated 2017/01/04 · openalex updated_date 2026/08/06
We construct and classify chiral topological phases in driven (Floquet) systems of strongly interacting bosons, with finite-dimensional site Hilbert spaces, in two spatial dimensions. The construction proceeds by introducing exactly soluble models with chiral edges, which in the presence of many-body localization (MBL) in the bulk are argued to lead to stable chiral phases. These chiral phases do not require any symmetry and in fact owe their existence to the absence of energy conservation in driven systems. Surprisingly, we show that they are classified by a quantized many-body index, which is well defined for any MBL Floquet system. The value of this index, which is always the logarithm of a positive rational number, can be interpreted as the entropy per Floquet cycle pumped along the edge, formalizing the notion of quantum-information flow. We explicitly compute this index for specific models and show that the nontrivial topology leads to edge thermalization, which provides an interesting link between bulk topology and chaos at the edge. We also discuss chiral Floquet phases in interacting fermionic systems and their relation to chiral bosonic phases.