arXiv subjects

Renné Medeiros de Araújo

Publications and source records attributed to Renné Medeiros de Araújo.

5 recordsLinked to original sources

arXiv2026

Measuring Geometric Phase based on Indefinite Causal Order in a Sagnac Interferometer

Sagnac interferometers are important tools for precision measurements. Cancellation of common-path noise ensures a high degree of stability against external perturbations, while their sensitivity to rotations provides the basis of laser gyroscopes. Here we highlight another, less explored feature of Sagnac interferometers: the fact that optical elements are traversed in reverse order for clockwise and counterclockwise propagating light components. This provides the opportunity to explore a classical realization of indefinite causal order, where the order of events within a sequence is not fixed. We explore this concept to identify the geometric phase associated with two non-commuting polarization operations with a single measurement. This idea may have applications for the rapid determination of polarization manipulations or optical activity within chiral media, but foremost it provides a geometric illustration of indefinite causal order.

physics.optics↗

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↗

arXiv2018

Phase conjugation and mode conversion in stimulated parametric down-conversion with orbital angular momentum: a geometrical interpretation

We report on an experiment that investigates the spatial mode conversion in the process of parametric down-conversion seeded by a light beam in a superposition of orbital angular momentum modes. This process is interpreted in terms of a geometric representation of first-order spatial modes in a Poincaré sphere, providing an intuitive image of the phase conjugation and the topological charge conservation. We also make a comparison with the analogous phenomenon for optical parametric oscillators.

physics.optics↗

arXiv2014

Full characterization of a highly multimode entangled state embedded in an optical frequency comb using pulse shaping

We present a detailed analysis of the multimode quantum state embedded in an optical frequency comb generated by a Synchronously Pumped Optical Parametric Oscillator (SPOPO). The full covariance matrix of the state is obtained with homodyne detection where the local oscillator is spectrally controlled with pulse shaping techniques. The resulting matrix reveals genuine multipartite entanglement. Additionally, the beam is comprised of several independent eigenmodes that correspond to specific pulse shapes. The experimental data is confirmed with numerical simulations. Finally, the potential to create continuous-variable cluster states from the quantum comb is analyzed. Multiple cluster states are shown to be simultaneously embedded in the SPOPO state, and these states can be revealed by a suitable basis change applied to the measured covariance matrix.

quant-ph↗