arXiv subjects

O. A. Herrera-Sancho

Publications and source records attributed to O. A. Herrera-Sancho.

9 recordsLinked to original sources

arXiv2021

MgO surface lattice phonons observation during Interstellar ice transition

Relevant information on the origins of the solar system and the early evolution of life itself can be derive from systematic and controlled exploration of amorphous water ice here on Earth. Therefore, over the last decades, a huge effort on experimental methodologies has been made to study the multiple crystal ice phases, which are observed outside our home-gravitational-potential. By employing (100)-oriented MgO lattice surface as a microcantilever sensor, we conducted the first ever study on the dynamics of the Structural Phase Transition at 185 K in amorphous water ice by means of coherent elastic scattering of electron diffraction. We estimate the amount of phonons caused by this transition applying precise quantum computing key tools, resulting in a maximum value of 1.23 $\pm$ 0.02. Further applications of our microcantilever sensor were assessed using unambiguous mapping of the surface stress induced by the c(4$\times$2) $\longleftrightarrow$ p(3$\times$2) Structural Phase Transition of the interstellar ice formulated on the Williamsom-Hall model. This development paves the way and thus establishes an efficient characterization tool of the surface mechanical strains of materials with potential applications arising from interstellar ice inclusive glaciers to the wide spectrum of solid-state physics.

cond-mat.mtrl-sci↗

arXiv2021

Revealing time's secrets at the National Theatre of Costa Rica: innovative software for cultural heritage research

Establishing affordable, efficient, accessible, innovative, and multidisciplinary methodologies are key to the creation of modern public policies on cultural heritage. Limited access to large-format paintings is a challenge to restoration scientists seeking to obtain information quickly, in a non-invasive manner, and identify regions of interest. Therefore, we put forward two unique software tools based on multispectral imaging techniques, with the long-term aim of assessing the artist's intentions, creative process, and color palette. This development paves the way for a comprehensive and multidisciplinary understanding of the mysteries encompassed in each pictorial layer, through the study of their physical and chemical characteristics. We conducted the first-ever study on Musas I and II, two large-format paintings by Italian artist Carlo Ferrario, located in the National Theatre of Costa Rica. In this study, we used our novel techniques to chose regions of interest in order to study sample layers; while also assessing the works' state of conservation and possible biodeterioration. We explored the applications of our two versatile software tools, RegionOfInterest and CrystalDistribution, and confirmed paint stratigraphies by means of microscopy and spectroscopy analyses. In a pilot study, we identified the artist's main color palette: zinc white, lead white, chrome yellow, lead read, viridian, along with artificial vermilion and ultramarine pigments. We were able to identify artificial vermilion and ultramarine and distinguish them from the natural pigments using CrystalDistribution to map the average size and diameter of the pigment crystals within the paint layers. This study demonstrated that software-based multidisciplinary imaging techniques are fundamental in establishing preventive and non-invasive methods for historical painting conservation studies and virtual restoration.

physics.app-ph↗

arXiv2021

Continuous slowing of a gadolinium atomic beam

The article presents the development of a new and innovative experimental method to fully characterize a solenoidal "spin-flip" Zeeman slower (ZS) using a Quartz Crystal $μ$-balance (QCM) as a kinetic energy sensor. In this experiment, we focus a 447.1 nm laser into a counter-propagating beam of gadolinium (Gd) atoms in order to drive the dipole transition between ground $^{9}$D$^{0}_{2}$ state and $^{9}$D$_{3}$ excited state. The changes in the velocity of the beam were measured using a QCM during this process, as a novel and alternative method to characterize the efficiency of a 1 m-long spin-flip Zeeman slower. The QCM, normally used in solid-state physics, is continuously and carefully monitored to determine the change in its natural frequency of oscillation. These changes reveal a direct relation with changes in the deposition rate and the momentum exchanged between the QCM and Gd atoms. Hence, in terms of ultracold atom physics, it might be used to study the time-evolution of the velocity distribution of the atoms during the cooling process. By this method, we obtain a maximum atom average velocity reduction of (43.5 $\pm$ 6.4)$\%$ produced by our apparatus. Moreover, we estimate an experimental lifetime of $τ_{e}$ = 8.2 ns for the used electronic transition, and then we compared it with the reported lifetime for 443.06 nm and 451.96 nm electronic transitions of Gd. These results confirm that the QCM offers an accessible and simple solution to take into account for laser cooling experiments. Therefore, a novel and innovative technique can be available for future experiments.

physics.atom-ph↗

arXiv2020

A pulsed ion microscope to probe quantum gases

The advent of the quantum gas microscope allowed for the in situ probing of ultracold gaseous matter on an unprecedented level of spatial resolution. The study of phenomena on ever smaller length scales as well as the probing of three-dimensional systems is, however, fundamentally limited by the wavelength of the imaging light, for all techniques based on linear optics. Here we report on a high-resolution ion microscope as a versatile and powerful experimental tool to investigate quantum gases. The instrument clearly resolves atoms in an optical lattice with a spacing of $532\,\text{nm}$ over a field of view of 50 sites and offers an extremely large depth of field on the order of at least $70\,μ\text{m}$. With a simple model, we extract an upper limit for the achievable resolution of approximately $200\,\text{nm}$ from our data. We demonstrate a pulsed operation mode which in the future will enable 3D imaging and allow for the study of ionic impurities and Rydberg physics.

physics.atom-ph↗

arXiv2015

Detection of the adsorption of water monolayers through the ion oscillation frequency in the magnesium oxide lattice by means of Low Energy Electron Diffraction

We investigate the variation of the oscillation frequency of the Mg$^{2+}$ and O$^{2-}$ ions in the magnesium oxide lattice due to the interactions of the surface with water monolayers by means of Low Energy Electron Diffraction. Our key result is a new technique to determine the adsorbate vibrations produced by the water monolayers on the surface lattice as a consequence of their change in the surface Debye temperature and its chemical shift. The latter was systematically investigated for different annealing times and for a constant external thermal perturbation in the range of 110-300 K in order to accomplish adsorption or desorption of water monolayers in the surface lattice.

cond-mat.mtrl-sci↗

arXiv2015

Sympathetic cooling and detection of a hot trapped ion by a cold one

We investigate the dynamics of an ion sympathetically cooled by another laser-cooled ion or small ion crystal. To this end, we develop simple models of the cooling dynamics in the limit of weak Coulomb interactions. Experimentally, we create a two-ion crystal of Ca$^+$ and Al$^+$ by photo-ionization of neutral atoms produced by laser ablation. We characterize the velocity distribution of the laser-ablated atoms crossing the trap by time-resolved fluorescence spectroscopy. We observe neutral atom velocities much higher than the ones of thermally heated samples and find as a consequence long sympathethic cooling times before crystallization occurs. Our key result is a new technique for detecting the loading of an initially hot ion with energy in the eV range by monitoring the motional state of a Doppler-cooled ion already present in the trap. This technique not only detects the ion but also provides information about dynamics of the sympathetic cooling process.

quant-ph↗

arXiv2013

Energy levels of Th+ between 7.3 and 8.3 eV

Using resonant two-step laser excitation of trapped 232Th+ ions, we observe 43 previously unknown energy levels within the energy range from 7.3 to 8.3 eV. The high density of states promises a strongly enhanced electronic bridge excitation of the 229mTh nuclear state that is expected in this energy range. From the observation of resonantly enhanced three-photon ionization of Th+, the second ionization potential of thorium can be inferred to lie within the range between 11.9 and 12.3 eV. Pulsed laser radiation in a wide wavelength range from 237 to 289 nm is found to provide efficient photodissociation of molecular ions that are formed in reactions of Th+ with impurities in the buffer gas, leading to a significantly increased storage time for Th+ in the ion trap.

physics.atom-ph↗

arXiv2012

Two-photon laser excitation of trapped 232Th+ ions via the 402 nm resonance line

Experiments on one- and two-photon laser excitation of 232Th+ ions in a radiofrequency ion trap are reported. As the first excitation step, the strongest resonance line at 402 nm from the 6d^2 7s J=3/2 ground state to the 6d7s7p J=5/2 state at 24874 cm^{-1} is driven by radiation from an extended cavity diode laser. Spontaneous decay of the intermediate state populates a number of low-lying metastable states, thus limiting the excited state population and fluorescence signal obtainable with continuous laser excitation. We study the collisional quenching efficiency of helium, argon, and nitrogen buffer gases, and the effect of repumping laser excitation from the three lowest-lying metastable levels. The experimental results are compared with a four-level rate equation model, that allows us to deduce quenching rates for these buffer gases. Using laser radiation at 399 nm for the second step, we demonstrate two-photon excitation to the state at 49960 cm^{-1}, among the highest-lying classified levels of Th+. This is of interest as a test case for the search for higher-lying levels in the range above 55000 cm^{-1} which can resonantly enhance the excitation of the 229Th+ nuclear resonance through an inverse two-photon electronic bridge process.

physics.atom-ph↗

arXiv2011

Laser ablation loading of a radiofrequency ion trap

The production of ions via laser ablation for the loading of radiofrequency (RF) ion traps is investigated using a nitrogen laser with a maximum pulse energy of 0.17 mJ and a peak intensity of about 250 MW/cm^2. A time-of-flight mass spectrometer is used to measure the ion yield and the distribution of the charge states. Singly charged ions of elements that are presently considered for the use in optical clocks or quantum logic applications could be produced from metallic samples at a rate of the order of magnitude 10^5 ions per pulse. A linear Paul trap was loaded with Th+ ions produced by laser ablation. An overall ion production and trapping efficiency of 10^-7 to 10^-6 was attained. For ions injected individually, a dependence of the capture probability on the phase of the RF field has been predicted. In the experiment this was not observed, presumably because of collective effects within the ablation plume.

physics.atom-ph↗