Direct measurement of the Zak phase in topological Bloch bands

Marcos Atala, Monika Aidelsburger, Julio T. Barreiro, Dmitry Abanin, Takuya Kitagawa, Eugene Demler, Immanuel Bloch

Research output: Contribution to journalArticlepeer-review

780 Scopus citations

Abstract

Geometric phases that characterize the topological properties of Bloch bands play a fundamental role in the band theory of solids. Here we report on the measurement of the geometric phase acquired by cold atoms moving in one-dimensional optical lattices. Using a combination of Bloch oscillations and Ramsey interferometry, we extract the Zak phase - the Berry phase gained during the adiabatic motion of a particle across the Brillouin zone - which can be viewed as an invariant characterizing the topological properties of the band. For a dimerized lattice, which models polyacetylene, we measure a difference of the Zak phase δφ Zak = 0.97(2)π for the two possible polyacetylene phases with different dimerization. The two dimerized phases therefore belong to different topological classes, such that for a filled band, domain walls have fractional quantum numbers. Our work establishes a new general approach for probing the topological structure of Bloch bands inoptical lattices.

Original languageEnglish (US)
Pages (from-to)795-800
Number of pages6
JournalNature Physics
Volume9
Issue number12
DOIs
StatePublished - Dec 2013
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • General Physics and Astronomy

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