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Characterizing the Haldane Phase in Quasi-1D Systems

Speaker: 
Keola Wierschem (National Taiwan University)
Date: 
Tue, 13/01/2015 - 11:00am to 12:00pm
Location: 
Graphene Theory Common Seminar Room (S16-06)
Host: 
Vitor Pereira
Event Type: 
Seminars

Abstract

The Haldane phase in antiferromagnetic spin-1 Heisenberg chains is an early example of a nontrivial symmetry protected topological (SPT) state. The topological nature of this phase is manifest by a hidden symmetry breaking characterized by nonlocal string order. The Haldane phase has been experimentally observed in low dimensional spin-1 quantum magnets, such as NENP and NDMAP. These systems possess weak interchain couplings that prevent any meaningful characterization by string order, so it is unclear whether or not they remain SPT states. Recently, a so-called strange correlator has been proposed to detect SPT states. Defined as a correlation function at the temporal boundary between an SPT state and a trivial product state, the strange correlator has been shown to be long-range or quasi-long-range in one or two dimensions. In this talk, I will describe how to measure the strange correlator using quantum Monte Carlo and present some results for the strange correlator in quasi-one-dimensional Haldane gap systems.

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