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Biphoton generation in quadratic waveguide arrays: A classical optical simulation

Markus Gräfe, Alexander S. Solntsev, Robert Keil +6 more

∗ both authors contributed equally Quantum entanglement, the non-separability of a multipartite wave function, became essential in understanding the non-locality of quantum mechanics. In optics, this non-locality can be demon-strated on impressively large length scales, as photons travel with the speed of light and interact only weakly with their environment. With the discovery of spontaneous parametric down-conversion (SPDC) in nonlinear crystals, an efficient source for entangled photon pairs, so-called biphotons, be-came available. It has recently been shown that SPDC can also be implemented in nonlinear arrays of evanescently coupled waveguides which allows the generation and the investigation of correlated quantum walks of such biphotons in an integrated device. Here, we analytically and experimentally demonstrate that the biphoton degrees of freedom are entailed in an additional spatial dimension, therefore the SPDC and the subsequent quantum random walk in one-dimensional (1D) arrays can be simulated through classical optical beam propagation in a two-dimensional (2D) photonic lattice. Thereby, the output intensity images directly represent the biphoton correlations and exhibit a clear violation of a Bell-type inequality. PACS numbers: 42.50.-p, 42.82.Et, 42.65.Lm∗ both authors contributed equally Quantum entanglement, the non-separability of a multipartite wave function, became essential in understanding the non-locality of quantum mechanics. In optics, this non-locality can be demon-strated on impressively large length scales, as photons travel with the speed of light and interact only weakly with their environment. With the discovery of spontaneous parametric down-conversion (SPDC) in nonlinear crystals, an efficient source for entangled photon pairs, so-called biphotons, be-came available. It has recently been shown that SPDC can also be implemented in nonlinear arrays of evanescently coupled waveguides which allows the generation and the investigation of correlated quantum walks of such biphotons in an integrated device. Here, we analytically and experimentally demonstrate that the biphoton degrees of freedom are entailed in an additional spatial dimension, therefore the SPDC and the subsequent quantum random walk in one-dimensional (1D) arrays can be simulated through classical optical beam propagation in a two-dimensional (2D) photonic lattice. Thereby, the output intensity images directly represent the biphoton correlations and exhibit a clear violation of a Bell-type inequality. PACS numbers: 42.50.-p, 42.82.Et, 42.65.Lm

Aug 16, 201629 citations

Exploring complex graphs with 3D quantum walks of correlated photons

Max Ehrhardt, Robert Keil, Lukas J. Maczewsky +2 more

We study three-dimensional quantum walks on complex graphs arising from the hybrid action of the spatial and polarization degrees of freedom for single photons in photonic waveguide circuits with tailored birefringence.

Conference on Lasers and Electro-OpticsJan 1, 20200 citations

Quantum random walks circuits with photonic waveguides

Alberto Peruzzo, Jonathan C. F. Matthews, Alberto Politi +10 more

Arrays of 21 evanescently coupled waveguides are fabricated to implement quantum random walks and a generalised form of two-photon non-classical interference, which observed via two photon correlation.

Apr 7, 20101 citation

Quantum Correlations in Two-Dimensional Waveguide Arrays and their Classical Simulation

Robert Keil, Felix Dreisow, Matthias Heinrich +3 more

We theoretically analyse the propagation of photon pairs in two-dimensional (2D) photonic lattices by evaluating their photon number correlation. We support our results by classical intensity correlation experiments acting as a unbiased quantum simulator.

Frontiers in OpticsJan 1, 20100 citations

Nonlinear Quantum Walks at the Edge of Quadratic Waveguide Arrays

Alexander S. Solntsev, Frank Setzpfandt, Alex S. Clark +9 more

We realize experimentally quantum walks of photon-pairs generated in a quadratic nonlinear waveguide array, and demonstrate that the pump distance from the edge strongly affects the spatial correlations through the interference from virtual biphoton sources.

Nonlinear OpticsJan 1, 20130 citations

Multi-particle Quantum Walks with 2D & 3D Arrayed Waveguides

Konstantinos Poulios, Daniel Fry, Mirko Lobino +12 more

Multi-photon quantum walks on integrated circuits are emonstrated, showing non-classical correlations, in one and two dimensional networks. Time evolution of quantum walks and a scheme for simulating fermionic quantum walks using entanglement are demonstrated.

Apr 17, 20120 citations

Classical characterisation of correlated biphotons in waveguide lattices

Abstract

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Classical characterisation of correlated biphotons in waveguide lattices

Abstract

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