Exactly Solvable Points and Symmetry Protected Topological Phases of Quantum Spins on a Zig-Zag Lattice
Date
2019
Authors
Zou, Haiyuan
Zhao, Erhai
Guan, Xi-Wen
Liu, W. Vincent
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American Physical Society
Abstract
A large number of symmetry-protected topological (SPT) phases have been hypothesized for strongly interacting spin-1=2 systems in one dimension. Realizing these SPT phases, however, often demands finetuningshardtoreachexperimentally.Andthelackofanalyticalsolutionshinderstheunderstandingoftheir many-body wave functions. Here we show that two kinds of SPT phases naturally arise for ultracold polar molecules confined in a zigzag optical lattice. This system, motivated by recent experiments, is described byaspinmodelwhoseexchangecouplingscanbetunedbyanexternalfieldtoreachparameterregionsnot studied before for spin chains or ladders. Within the enlarged parameter space, we find the ground state wavefunctioncanbeobtainedexactlyalongalineandataspecialpoint,forthesetwophases,respectively. These exact solutions provide a clear physical picture for the SPT phases and their edge excitations. We further obtain the phase diagram by using infinite time-evolving block decimation and discuss the phase transitions between the two SPT phases and their experimental signatures.
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Physical Review Letters
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Journal article
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Open Access
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