arXiv subjects

Anderson M. Amaral

Publications and source records attributed to Anderson M. Amaral.

8 recordsLinked to original sources

arXiv2026

Observation of Replica Symmetry Breaking in Filamentation and Multifilamentation

We report the experimental observation and characterization of Replica Symmetry Breaking (RSB) manifestation while analyzing the transverse intensity profile of pulses in filamentation experiments using sapphire crystal and distilled water, excited by a femtosecond laser centered at 800 nm. The RSB arises from the competition between self-focusing and plasma defocusing, subject to local fluctuations in the nonlinear refractive index generated by plasma via multiphoton excitation, which subsequently promotes frustration among modes. Our results confirm the existence of glassy-like photonic states not only in multifilamentation, as previously reported [W. Ettoumi, J. Kasparian, and J. Wolf, "Spin-glass model governs laser multiple filamentation," Phys. Rev. Lett., vol. 115, no. 3, pp. 033902, 2015], but also in the generation of a single filament and in filamentation accompanied by conical emission. These findings improve the understanding of statistical nonlinear optics by establishing connections with magnetism and highlighting the glassy-like behavior of light in the context of ultrafast optical phenomena.

physics.optics↗

arXiv2026

Real-time ESR tracking for sub-micron 3D magnetic mapping with VB- quantum sensors in hexagonal boron nitride

The discovery of spin-dependent luminescent properties of negatively charged boron-vacancy centers ($V^-_B$) in hexagonal boron nitride (hBN) enabled a new platform for quantum sensing with van der Waals materials. Particularly, the possibility of performing optically detected magnetic resonance (ODMR) for determining the electron spin resonance (ESR) frequencies of hBN color centers became a strong tool for quantum sensing of magnetic fields with submicrometric resolution. However, due to low ODMR contrast, current techniques proposed for mapping DC magnetic fields require hours of integration to obtain a magnetic image of a micron-sized region. In this work, we report the implementation of a frequency-tracking approach for real-time monitoring of ESR frequencies of localized $V^-_B$ centers in hBN. With this technique, magnetic field monitoring was used to map the field pattern generated by a micron-sized conical magnetic tip in only a few minutes. By controlling the magnetic sample's position relative to the quantum sensor, three-dimensional magnetic mapping of the field was achieved with diffraction-limited resolution and shot-noise-limited sensitivity of 54 $μ$T$/\sqrt{\text{Hz}}$. Magnetic field gradients of 3.6 $\pm$ 0.2 $μ$T/nm were measured with our system, in which a maximum detected field rate of 6 mT/s was achieved. The results of this study establish spin resonance frequency-tracking as a viable technique and fast method for minute-scale magnetic imaging, reducing acquisition times by at least one order of magnitude if compared to conventional techniques.

physics.chem-ph↗

arXiv2026

Absolute Primary Nanothermometry Using Individual Stark Sublevels of Rare-Earth-doped Crystals

We present two independent optical methods for absolute primary thermometry using rare-earth-doped nanoparticles. Both approaches rely exclusively on the internal energy levels and population dynamics of the dopant ions, eliminating the need for external temperature references. We experimentally demonstrate the concepts by using Y$_2$O$_3$: Yb$^{3+}$/Er$^{3+}$ nanoparticles, exploiting Boltzmann distribution between individual Stark sublevels of the Er$^{3+}$ ions, emitting in the green spectral region ($\sim$550 nm) and in the near-infrared spectral region ($\sim$1600 nm). Our strategy establishes rare-earth-based luminescence thermometers as genuine absolute primary probes, conceptually comparable to Johnson noise and acoustic gas thermometers, but with the fundamental advantage of possibly being employed at the nanoscale, potentially down to the single-ion limit, with optical readout and over wide temperature ranges.

physics.chem-ph↗

arXiv2025

Boltzmann Thermometry at Cryogenic Temperatures Exploiting Stark Sublevels in Er$^{3+}$/Yb$^{3+}$-Codoped Yttrium Oxide Nanoparticles

The development of reliable luminescent nanothermometers for cryogenic applications is essential for advancing quantum technologies, superconducting systems, and other fields that require precise, high-spatial-resolution temperature monitoring. Lanthanide-doped systems are vastly employed to this purpose, and typically perform optimally at or above room temperature when manifold-to-manifold transitions are used. In this work we exploit individual Stark sublevels to demonstrate an optical thermometer based on Er$^{3+}$/Yb$^{3+}$ codoped yttria (Y$_2$O$_3$) nanoparticles that operates effectively across the temperature range from 25 K to 175 K. This is achieved due to the pronounced crystal field environment of the the Y$_2$O$_3$ host matrix, leading to well-separated Stark lines in the luminescence spectrum of the Er$^{3+}$ ions. By applying the Luminescence Intensity Ratio (LIR) method to transitions originating from two Stark components of the $^4$S$_{3/2}$ manifold of the Er$^{3+}$ ions, we achieve thermal sensitivities up to 1.25 % K$^{-1}$ at 100 K and temperature resolutions reaching 0.2 K. Our results further experimentally confirm recently published theoretical predictions, demonstrating that thermometric performance is not directly dependent on the average (barycenter) difference of the involved electronic energy levels when using individual Stark transitions to evaluate the LIR. The proposed procedure gives an energy gap calibration that matches the one determined by sample spectroscopy for non-overlapping lines in the luminescence spectrum. These insights provide a robust foundation for the design of high-performance cryogenic thermometers based on rare-earth-doped materials.

physics.chem-ph↗

arXiv2025

Addressing Discrepancies Between Theory and Experiments in Boltzmann Luminescence Thermometry with Ln3+ Ions

Trivalent lanthanide ion-doped nanoparticles are widely employed as nanoscale thermometers, driving rapid advancements in real-world applications. When the Luminescence Intensity Ratio (LIR) technique is used, these thermometric systems typically require a calibration process to obtain macroscopic calibration parameters. However, despite extensive studies from various research groups, significant discrepancies are observed among the reported values, even for identical Ln$^{3+}$-host systems under similar experimental conditions. Also, in many cases, the obtained calibration parameters substantially differ from their microscopic counterparts, which is commonly ignored in the literature. This study addresses some sources for these inconsistencies by providing fundamental theoretical insights into the measurement process. We demonstrate that the thermalization of the electronic population within the Stark sublevels of a given manifold plays a crucial role in the LIR's temperature dependence and consequently in measuring the macroscopic parameters. As a result, attempts to construct primary thermometers without prior calibration can result in temperature measurement errors exceeding 20 K. Additionally, we show that pathways disrupting Boltzmann thermalization, influenced by experimental conditions, also affect the evaluation of the macroscopic quantities. These findings contribute to a more robust theoretical framework for interpreting and understanding ratiometric Boltzmann luminescence thermometry experiments, also paving the way for developing more accurate and reliable primary thermometers.

physics.chem-ph↗

arXiv2020

Observation and analysis of creation, decay, and regeneration of annular soliton clusters in a lossy cubic-quintic optical medium

We observe and analyze formation, decay, and subsequent regeneration of ring-shaped clusters of (2+1)-dimensional spatial solitons (filaments) in a medium with the cubic-quintic (focusing-defocusing) self-interaction and strong dissipative nonlinearity. The cluster of filaments, that remains stable over ~17.5 Rayleigh lengths, is produced by the azimuthal modulational instability from a parent ring-shaped beam with embedded vorticity l = 1. In the course of still longer propagation, the stability of the soliton cluster is lost under the action of nonlinear losses. The annular cluster is then spontaneously regenerated due to power transfer from the reservoir provided by the unsplit part of the parent vortex ring. A (secondary) interval of the robust propagation of the regenerated cluster is identified. The experiments use a laser beam (at wavelength 800 nm), built of pulses with temporal duration 150 fs, at the repetition rate of 1 kHz, propagating in a cell filled by liquid carbon disulfide. Numerical calculations, based on a modified nonlinear Schrödinger equation which includes the cubic-quintic refractive terms and nonlinear losses, provide results in close agreement with the experimental findings.

nlin.PS↗

arXiv2015

Optical vortices: the concept of topological potential and analogies with two-dimensional electrostatics

We show how the phase profile of a distribution of topological charges (TC) of an optical vortex (OV) can be described by a potential analogous to the Coulomb's potential for a distribution of electric charges in two-dimensional electrostatics. From what we call the Topological Potential (TP), the properties of TC multipoles and a 2D radial distribution were analyzed. The TC multipoles have a transverse profile that is topologically stable under propagation and may be exploited in optical communications; on the other hand, the 2D distributions can be used to tune the transverse forces in optical tweezers. Considering the analogies with the electrostatics formalism, it is also expected that the TP allows the tailoring of OV for specific applications.

physics.optics↗

arXiv2014

Distinguishing orbital angular momenta and topological charge in optical vortex beams

In this work we discuss how the classical orbital angular momentum (OAM) and topological charge (TC) of optical beams with arbitrary spatial phase profiles are related to the local winding density. An analysis for optical vortices (OV) with non-cylindrical symmetry is presented and it is experimentally shown for the first time that OAM and TC may have different values. The new approach also provides a systematic way to determine the uncertainties in measurements of TC and OAM of arbitrary OV.

physics.optics↗