arXiv subjects

Paulo Henrique Souto Ribeiro

Publications and source records attributed to Paulo Henrique Souto Ribeiro.

5 recordsLinked to original sources

arXiv2025

Brazilian Twin Photons 32nd anniversary

We present a historical review of the development and impact of spontaneous parametric down-conversion (SPDC) in Brazil, marking over three decades since the first twin-photon experiments were performed in the country. This article traces the pioneering efforts that initiated the field, highlighting key experiments, institutions, and researchers who contributed to its growth. We discuss seminal works that established SPDC as a fundamental tool in the Brazilian Quantum Optics community, including studies on spatial correlations, entanglement, and decoherence. By presenting a curated sequence of experiments, we offer an overview of how Brazilian research in twin-photon systems has explored profound concepts through fundamental demonstrations, leading to significant international impact. This review also highlights the formation of a strong scientific community and its ongoing efforts to turn fundamental knowledge into quantum applications.

quant-ph↗

arXiv2025

Experimental Investigation of Optical Processing With Spatial Light Modulation

The growing demand for real-time data processing in applications such as neural networks and embedded control systems has spurred the search for faster, more efficient alternatives to traditional electronic systems. In response, we experimentally investigate an optical processing scheme that encodes information in the transverse wavefront of light fields using spatial light modulators. Our goal is to explore the limits on parallelism imposed by technical constraints. We begin by implementing optical an XOR logic gate applied to binary matrices. By analyzing the average error rate in the optical operation between matrices of varying sizes (up to 300 x 300 elements), we analyze the bit depth capacity of the system and the role of information redundancy. Furthermore, we successfully demonstrate image encryption and decryption using a one-time pad protocol for matrices as large as 164 x 164 elements. These findings support the development of a high-dimensional matrix optical processor.

physics.optics↗

arXiv2023

Partial coherence and coherence length in StimPDC

In parametric down conversion, a nonlinear crystal is pumped by a laser and spontaneous emission takes place in signal and idler modes according to the phase matching conditions. A seed laser can stimulate the emission in the signal beam if there is mode overlap between them. This also enhances the emission in the idler beam, affecting its coherence properties. While the degree of coherence of the idler field as a function of the seed power has already been studied, the transverse coherence length has not yet been properly investigated. The transverse coherence length is a key parameter of optical beams that determines the beam divergence, for example. Here, we present a theoretical and experimental investigation of the transverse coherence length in stimulated down conversion. In addition, we make a connection between stimulated down conversion and partially coherent sources like the Gaussian Schell model beams, and show that in general the idler field cannot be described with this model.

physics.optics↗

arXiv2022

Evaluation of Twisted Gaussian Schell Model beams produced with phase randomized coherent fields

The twisted Gaussian Schell Model describes a family of partially coherent beams that present several interesting characteristics, and as such have attracted attention in classical and quantum optics. Recent techniques have been demonstrated to synthesize these beams from a coherent source using a discrete set of "pseudo-modes", where the phase of each mode is randomized so that they are mutually incoherent. Here we investigate this technique and evaluate the resulting beam parameters, such as divergence, coherence length and twist phase. We show that for a finite set of modes there is also some residual coherence, which can have an observable effect. A theoretical model is developed for the output field that includes residual coherence and agrees very well with experimental data. In addition, we demonstrate a simple method to measure the twist phase using double slit interference.

physics.optics↗

arXiv2014

Optical integration of a real-valued function by measurement of a Stokes Parameter

We experimentally implement an optical algorithm for integration of a real-valued bivariate func- tion. A user-defined function is encoded in the position-dependent phase of one of the polarization components of an optical beam. The integral of this function is retrieved by measuring a Stokes parameter of the polarization. We analyze the performance of the system as an integration device.

physics.optics↗