arXiv subjects

Paulo H. Souto Ribeiro

Publications and source records attributed to Paulo H. Souto Ribeiro.

5 recordsLinked to original sources

arXiv2025

Experimental Investigation of Twist Conservation in Nonlinear Optical Three-Wave Mixing

We conduct an experimental investigation into the conservation of the twist phase in Twisted Gaussian Schell Model (TGSM) beams during both up- and down-conversion three-wave mixing nonlinear processes. Independently generated TGSM beams, prepared with varying twist parameters, are used to pump and seed the nonlinear interactions. The resulting beams are then analyzed to determine their twist properties. Our findings demonstrate that the twists of the up- and down-converted beams depend on those of the pump and seed beams. Additionally, the results indicate that the twist phase is conserved throughout the process, in qualitative agreement with theoretical predictions. This study is motivated by the increasing potential applications of TGSM beams in various fields.

physics.optics↗

arXiv2022

Enhanced Photonic Maxwell's Demon with Correlated Baths

Maxwell's Demon is at the heart of the interrelation between quantum information processing and thermodynamics. In this thought experiment, a demon generates a temperature gradient between two thermal baths initially at equilibrium by gaining information at the single-particle level and applying classical feed-forward operations, allowing for the extraction of work. Here we implement a photonic version of Maxwell's Demon with active feed-forward in a fibre-based system using ultrafast optical switches. We experimentally show that, if correlations exist between the two thermal baths, the Demon can generate a temperature difference over an order of magnitude larger than without correlations, and so extract more work. Our work demonstrates the great potential of photonic experiments -- which provide a unique degree of control on the system -- to access new regimes in quantum thermodynamics.

quant-ph↗

arXiv2020

Transfer of angular spectrum in parametric down-conversion with structured light

We develop the formal approach to the angular spectrum transfer in parametric down-conversion that allows pumping with a structured beam. The scheme is based on an entangled photon source pumped by a laser beam structured with a vector-vortex polarization profile. This creates a two-photon quantum state exhibiting polarization-dependent transverse correlations that can be accessed through coincidence measurements on the spatially separated photons. The calculated correlations are shown to present a spin-orbit profile typical of vector beams, however, distributed on separate measurement regions. Our approach allows the design of the pump beam vector spatial structure and measurement strategies for potential applications of these entangled states, such as in quantum communication.

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↗

arXiv2018

Testing for entanglement with periodic coarse-graining

Continuous variables systems find valuable applications in quantum information processing. To deal with an infinite-dimensional Hilbert space, one in general has to handle large numbers of discretized measurements in tasks such as entanglement detection. Here we employ the continuous transverse spatial variables of photon pairs to experimentally demonstrate novel entanglement criteria based on a periodic structure of coarse-grained measurements. The periodization of the measurements allows for an efficient evaluation of entanglement using spatial masks acting as mode analyzers over the entire transverse field distribution of the photons and without the need to reconstruct the probability densities of the conjugate continuous variables. Our experimental results demonstrate the utility of the derived criteria with a success rate in entanglement detection of $\sim60\%$ relative to $7344$ studied cases.

quant-ph↗