Topological polarisation states

Polarisation states are described by spin expectation values, known as Stokes parameters, the trajectories of which in a rotationally symmetric system form a sphere named after Poincaré. Here, we show that the trajectories of broken rotational symmetric systems can exhibit distinct topological struc...

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Bibliographic Details
Published inFrontiers in physics Vol. 11
Main Author Saito, Shinichi
Format Journal Article
LanguageEnglish
Published Frontiers Media S.A 08.09.2023
Subjects
coherent state
Poincaré sphere
polarisation
spin angular momentum
Stokes parameters
topology
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Summary:Polarisation states are described by spin expectation values, known as Stokes parameters, the trajectories of which in a rotationally symmetric system form a sphere named after Poincaré. Here, we show that the trajectories of broken rotational symmetric systems can exhibit distinct topological structures in polarisation states. We use a phase-shifter to form a polarisation circle ( S 1 ) , which interferes with the original input due to the phase change of the output state upon rotation. By rotating the circle using a rotator, the trajectories become a polarisation torus ( S 1 × S 1 ) , which was experimentally confirmed in a simple setup using passive optical components together with the Mach–Zehnder interferometer. We also discuss the realisations of other topological features, such as a Möbius strip, a trefoil knot, Hopf links, and topological Dirac bosons, with a bulk-edge correspondence.
ISSN:2296-424X
2296-424X
DOI:10.3389/fphy.2023.1225462