Photonics Research, Volume. 9, Issue 1, A1(2021)
Photonic two-particle quantum walks in Su–Schrieffer–Heeger lattices
Fig. 1. Band structure of the Su–Schrieffer–Heeger model. (A) The SSH model describes a one-dimensional lattice with alternating nearest-neighbor couplings. For
Fig. 2. Experimental setup. (A) Direct laser writing technique: femtosecond-laser pulses are focused into a moving glass sample, forming a waveguide trajectory. (B) Waveguide structure, consisting of an incoupling fanning, the actual SSH waveguide lattice with alternating couplings, and a fan-out. The lattice can be excited in the bulk, at the trivial and topological edge. (C) The full experimental setup consists of a spontaneous parametric down conversion (SPDC) photon pair source, fiber arrays that couple the photons into and out of the functional structure on the chip, and avalanche photodetectors.
Fig. 3. Intensity propagation at the lattice edges. The figures on the left show the simulated intensity evolution along the
Fig. 4. Correlations in the SSH lattice. Two indistinguishable photons are launched into neighboring sites of a lattice at the topological edge, trivial edge, and bulk. The coincidence counts after the quantum walk are shown in the upper row, and the corresponding theory is depicted below. For comparison, a homogenous lattice is investigated on the right. On the topological edge, the photons tend to remain in the edge state, which clearly shows in the measurement. The diagonal elements of the correlation matrices are not accessible without photon number resolution and are therefore masked gray in the simulations.
Fig. 5. Inter-particle distance. Histogram for the distance between the photon pairs detected in the quantum walk (see Fig.
Fig. 6. Hong–Ou–Mandel dip of the photon pair source. The retrieved coincidence counts (pink) were fitted with a Gaussian function (black), characterizing the visibility at
Fig. 7. Additional simulations of intensity propagation for classical light launched into the edge neighboring waveguides.
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Friederike Klauck, Matthias Heinrich, Alexander Szameit. Photonic two-particle quantum walks in Su–Schrieffer–Heeger lattices[J]. Photonics Research, 2021, 9(1): A1
Special Issue: TOPOLOGICAL PHOTONICS AND BEYOND
Received: Sep. 1, 2020
Accepted: Nov. 14, 2020
Published Online: Dec. 25, 2020
The Author Email: Alexander Szameit (alexander.szameit@uni-rostock.de)