arXiv subjects

R. F. Barros

Publications and source records attributed to R. F. Barros.

7 recordsLinked to original sources

arXiv2025

Controlling quantum entanglement with classical non-separable light

Here we investigate the quantum frequency conversion of entangled photons driven by a classically non-separable laser beam. We show that the frequency conversion dynamics is described by a quantum channel that stems from the classical drive field through the channel-state duality - the quantum channel is dual to the classical coherence matrix of the drive field. This implies that the evolution of entanglement in the conversion process is bound by the classical non-separability of the drive field, a result that we confirm experimentally. Furthermore, we show that the conversion dynamics can be understood as a swapping operation between classical non-separability and entanglement, unveiling a physical connection between two fundamentally different concepts.

quant-ph↗

arXiv2025

Optimal beam displacement measurements using high-order structured light modes

We develop a novel technique to measure small angular and lateral displacements of structured light beams. The technique relies on using high-order Hermite-Gaussian (HG) and Laguerre-Gaussian (LG) modes, which have well-defined symmetry under inversion. We show that the displacements of such fields lead to a crosstalk with modes with opposite parity under inversion, which we measure optimally with an interferometric parity sorter. Using this technique, we achieve improvement factors of up 41 in the signal-to-noise ratio using Hermite-Gaussian modes and 21 using Laguerre-Gaussian modes with order up to 20, as compared to the fundamental Gaussian mode. Our results present a viable way of using structured light for metrology that does not demand quantum light or homodyne detection.

physics.optics↗

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↗

arXiv2021

Quantum-controlled cluster states

Quantum optical cluster states have been increasingly explored, in the light of their importance for measurement-based quantum computing. Here we set forth a new method for generating quantum controlled cluster states: pumping an optical parametric oscillator with spatially structured light. We show that state-of-the-art techniques for producing clusters in the spectral and temporal domains are improved by a structured light pump, which manipulates the spatial mode couplings in the parametric interaction. We illustrate the method considering a second-order pump structure, and show that a simple mode rotation yields different cluster states, including, but not limited to the two-dimensional square and hexagonal lattices. We also introduce a novel technique for generating non-uniform cluster states, and propose a simple setup for its implementation.

quant-ph↗

arXiv2021

Gouy-phase effects in the frequency combs of an optical parametric oscillator

We investigate the transverse mode effects on the frequency combs generated by a type-I optical parametric oscillator (OPO) below threshold. We take the diffraction effects fully into account, considering usual OPO architectures instead of the self-imaging design. Further, we show that an OPO pumped with structured light produces multiple frequency combs simultaneously, corresponding to different combinations of spatial modes in the downconverted fields. This result may apply to the production of hybrid multipartite entanglement in the spatiotemporal modes of a single OPO.

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↗