arXiv subjects

C. E. R. Souza

Publications and source records attributed to C. E. R. Souza.

10 recordsLinked to original sources

arXiv2021

Generalized Orbital Angular Momentum Symmetry in Parametric Amplification

We investigate interesting symmetry properties verified by the down-converted beams produced in optical parametric amplification with structured light. We show that the Poincaré sphere symmetry, previously demonstrated for first-order spatial modes, translates to a multiple Poincaré sphere structure for higher orders. Each one of these multiple spheres is associated with a two-dimensional subspace defined by a different value of the orbital angular momentum. Therefore, the symmetry verified by first order modes is reproduced independently in each subspace. This effect can be useful for parallel control of independently correlated beams.

physics.optics↗

arXiv2019

Fine-tuning of orbital angular momentum in an optical parametric oscillator

We investigate the dynamical properties of a type-II optical parametric oscillator pumped by a structured light beam carrying orbital angular momentum. Different dynamical regimes are theoretically derived and experimentally demonstrated, depending on the anisotropy effects imposed by the nonlinear medium. In a weakly anisotropic regime, fine-tuning of the orbital angular momentum transfer is obtained by adjusting the crystal parameters. Under strong anisotropy, orbital angular momentum transfer is not possible and a sharp dynamical behavior is observed, with abrupt switching between different transverse modes.

physics.optics↗

arXiv2018

Conditions for optical parametric oscillation with structured light pump

We investigate the transverse mode structure of the down-converted beams generated by a type-II optical parametric oscillator (OPO) driven by a structured pump. Our analysis focus on the selection rules imposed by the spatial overlap between the transverse modes of the three fields involved in the non-linear interaction. These rules imply a hierarchy of oscillation thresholds that determine the possible transverse modes generated by the OPO, as remarkably confirmed with experimental results.

physics.optics↗

arXiv2018

Contextuality in spin-orbit laser modes

We experimentally observed the violation of Kujula-Dzhafarov noncontextuality inequalities by non-separable spin-orbit laser modes. Qubits are encoded on polarization and transverse modes of an intense laser beam. A spin-orbit non-separable mode was produced by means of a radial polarization converter (S-plate). The results show that contextuality can be investigated by using spin-orbit modes in a simple way, corroborating recent works stating that such system can emulate single-photon experiments. Additionally, an improvement in the non-separable mode preparation allowed us to observe a greater violation of the Clauser-Horne-Shimony-Holt inequality for such system. The results are in very good agreement with the theoretical predictions of quantum mechanics.

quant-ph↗

arXiv2015

Tripartite non-separability in classical optics

It is possible to prepare classical optical beams which cannot be characterized by a tensor product of vectors describing each of their degrees of freedom. Here we report the experimental creation of such a non-separable, tripartite GHZ-like state of path, polarization and transverse modes of a classical laser beam. We use a Mach-Zehnder interferometer with an additional mirror and other optical elements to perform measurements that violate Mermin's inequality. This demonstration of a classical optical analogue of tripartite entanglement paves the path to novel optical applications inspired by multipartite quantum information protocols.

quant-ph↗

arXiv2015

Spin-orbit mode transfer via a classical analog of quantum teleportation

We translate the quantum teleportation protocol into a sequence of coherent operations involving three degrees of freedom of a classical laser beam. The protocol, which we demonstrate experimentally, transfers the polarisation state of the input beam to the transverse mode of the output beam. The role of quantum entanglement is played by a non-separable mode describing the path and transverse degrees of freedom. Our protocol illustrates the possibility of new optical applications based on this intriguing classical analogue of quantum entanglement.

quant-ph↗

arXiv2013

Topological phase structure of vector vortex beams

The topological phase acquired by vector vortex optical beams is investigated. Under local unitary operations on their polarization and transverse degrees of freedom, the vector vortices can only acquire discrete geometric phase values, 0 or $π\,$, associated with closed paths belonging to different homotopy classes on the SO(3) manifold. These discrete values are demonstrated through interferometric measurements and the spin-orbit mode separability is associated to the visibility of the interference patterns. The local unitary operations performed on the vector vortices involved both polarization and transverse mode transformations with birefringent wave plates and astigmatic mode converters. The experimental results agree with our theoretical simulations and generalize our previous results obtained with polarization transformations only.

quant-ph↗

arXiv2013

Playing a quantum game on polarization vortices

The quantum mechanical approach to the well known prisoners dilemma, one of the basic examples to illustrate the concepts of Game Theory, is implemented with a classical optical resource, nonquantum entanglement between spin and orbital degrees of freedom of laser modes. The concept of entanglement is crucial in the quantum version of the game, which brings novel features with a richer universe of strategies. As we show, this richness can be achieved in a quite unexpected context, namely that of paraxial spin-orbit modes in classical optics.

quant-ph↗

arXiv2007

Topological phase for spin-orbit transformations on a laser beam

We investigate the topological phase associated with the double connectedness of the SO(3) representation in terms of maximally entangled states. An experimental demonstration is provided in the context of polarization and spatial mode transformations of a laser beam carrying orbital angular momentum. The topological phase is evidenced through interferometric measurements and a quantitative relationship between the concurrence and the fringes visibility is derived. Both the quantum and the classical regimes were investigated.

quant-ph↗

arXiv2006

Optical parametric oscillation under injection of orbital angular momentum

We present a theoretical model for the spatial mode dynamics of an optical parametric oscillator under injection of orbital angular momentum. This process is then interpreted in terms of an interesting picture based on a Poincare representation of first order spatial modes. The spatial properties of the down-converted fields can be easily understood from their symmetries in this geometric representation. By considering the adiabatic mode conversion of the injected signal, we also predict the occurrence of a geometric phase conjugation in the down-converted beams. An experimental setup to measure this effect is proposed.

quant-ph↗