Yulieth Martinez

Rice University · Department of Physics and Astronomy

The application of geoconservation concepts in Cuba is very recent, despite the wide body of knowledge accumulated through the study of Cuban geology. Recently, the establishment and consolidation of a National System of Protected Areas that stresses interaction with scientific institutions has greatly helped initiate geoconservation in Cuba. In th...

La condición de destino turístico en el extremo occidental del país, unido a la influencia de las actividades agrícolas y forestales que se desarrollan en las zonas de amortiguamiento, ejercen una considerable presión antrópica que amenaza la integridad ecológica de los ecosistemas que se conservan en el Parque Nacional Viñales. Esta amenaza consta...

Managing waste water treatment is a valuable alternative for water resource depuration and reuse in small rural communities. This is actually a common practice and is being implanted into the territorial planning, based on sustainable use of the diverse systems. Despite the advantages and positive experiences obtained by the use of this techniques...

El Parque Nacional Viñales, es uno de los espacios protegidos más singulares de Cuba, no sólo por su belleza paisajística y sus valores biológicos. Destaca además, por su geodiversidad y en especial por su naturaleza cárstica, como sitio clásico para los estudios del carst tropical, con el mayor potencial de sistemas cavernarios del país. En los úl...

Photoassociative spectroscopy in an intercombination-line magneto-optical trap has determined the ground-state s-wave scattering lengths of88Sr and86Sr. Recent work with a crossed optical dipole trap allows us to study atoms in metastable states.

We survey recent experiments with ultracold strontium performed in our group. Trapping and cooling occurs in three stages: successive magneto-optical traps (MOTs) operating on the 461 nm and 689 nm transitions of strontium, respectively, are loaded to cool atoms to a temperature of 1 muK. Finally, atoms are loaded into a far-off-resonance optical d...

We perform high intensity, 2-photon photoassociation spectroscopy near the 461 nm ^1S0-^1P1 transition of strontium to determine the binding energy of the least bound level in the ground state atomic potential. Previous work by our group has constrained the value of the s-wave scattering length in both ^86Sr and ^88Sr. This work provides a more pre...

We implement an optical dipole trap in a crossed beam configuration for experiments with ultracold strontium. Strontium atoms cooled to nearly 1 muK are loaded into the optical dipole trap from a magneto-optical trap operating on the 689 nm intercombination line. Loading dynamics and characteristics of the far off-resonance dipole trap are explored...

A study of ion equilibration in annular regions of ultracold strontium plasmas is reported. Plasmas are formed by photoionizing laser-cooled atoms with a pulsed dye laser. The experimental probe is spatially-resolved absorption spectroscopy using the 2S1/2-2P<sub>1/2 transition of the Sr+ ion. The kinetic energy of the ions is calculated from the D...

We describe ongoing studies of ultracold atomic strontium using standard laser cooling and trapping techniques. An improved ultra-high vacuum system has been constructed, and magneto-optical trapping on both the dipole-allowed transition at 461 nm (blue) and the intercombination line at 689 nm (red) is performed. The transfer efficiency from the bl...

We present recent work toward achieving quantum degeneracy in Strontium. In the first stage of cooling, a MOT operating on the strong (gamma= (2pi)* 32 MHz), ^1S0->^1P1 transition cools 10^8 atoms to 2 mK. Approximately 50% of these atoms are transferred to a second-stage MOT operating on the weaker (gamma= (2pi)* 7.5 kHz) ^1S0->^3P1 intercombinati...

This work describes intensity saturation of photoassociative transitions of ^86Sr at the quantum mechanical unitarity limit. The saturation behavior, which results in a roll-over of the photoassociation rate for intensities greater than the saturation intensity, is reminiscent of Landau-Zener physics. Unlike other photoassociation spectroscopy (PAS...

Resumen: Entre los valores más reconocidos del Parque Nacional Viñales (Cuba) destacan su rica biodiversidad, el paisaje y las tradiciones culturales. Estos son elementos claves para su determinación como área protegida. Sin embargo, existe una interesante geodiversidad más reconocida en el ámbito científico nacional e internacional que el ámbito l...

We report the use of photoassociative spectroscopy to determine the ground-state $s$-wave scattering lengths for the main bosonic isotopes of strontium, $^{86}\mathrm{Sr}$ and $^{88}\mathrm{Sr}$. Photoassociative transitions are driven with a laser red detuned by up to 1400 GHz from the $^{1}S_{0}\mathrm{\text{$-${}}}^{1}P_{1}$ atomic resonance at...

Ultracold neutral plasmas are formed by photoionizing laser‐cooled atoms near the ionization threshold. Through the application of atomic physics techniques and diagnostics, these experiments stretch the boundaries of traditional neutral plasma physics. The electron temperature in these plasmas ranges from 1–1000 K and the ion temperature is around...

We report optical absorption imaging of ultracold neutral plasmas. Imaging allows direct observation of the ion density profile and expansion of the plasma. The frequency dependence of the plasma's optical depth gives the ion absorption spectrum, which is broadened by the ion motion. We use the spectral width to monitor ion equilibration in the fir...

The importance of the 5s^21S0 -- 5s5p^3P1 intercombination line of strontium (Sr) as a possible candidate for optical frequency standards requires precise knowledge of the properties of this transition. Using the established electron-shelving technique on a cloud of laser cooled and trapped Sr atoms, we measured the lifetime of the ^3P1 state. Stud...

We report photoassociative spectroscopy of 88Sr(2) in a magneto-optical trap operating on the 1S0-->3P1 intercombination line at 689 nm. Photoassociative transitions are driven with a laser red detuned by 600-2400 MHz from the 1S0-->1P1 atomic resonance at 461 nm. Photoassociation takes place at extremely large internuclear separation, and the phot...

We study equilibration of strongly coupled ions in an ultracold neutral plasma produced by photoionizing laser-cooled and trapped atoms. By varying the electron temperature, we show that electron screening modifies the equilibrium ion temperature. Even with few electrons in a Debye sphere, the screening is well described by a model using a Yukawa i...

Ultracold neutral plasmas are formed by photoionizing laser-cooled atoms near the ionization threshold. Through the application of atomic physics techniques and diagnostics, these experiments stretch the boundaries of traditional neutral plasma physics. The electron temperature in these plasmas ranges from 1-1000 K and the ion temperature is around...

Absorption imaging and spectroscopy can probe the dynamics of an ultracold neutral plasma during the first few microseconds after its creation. Quantitative analysis of the data, however, is complicated by the inhomogeneous density distribution, expansion of the plasma, and possible lack of global thermal equilibrium for the ions. In this article w...

Atoms irradiated by a laser beam experience a force due to the interaction of an induced dipole moment with the oscillating electric field. If the laser is red-detuned from an atomic resonance, it can form a conservative potential that traps atoms near the peak of the laser intensity. Such a trap can be used to increase atomic densities via evapora...

We probe the expansion of an ultracold strontium plasma with spectroscopy of the ^2S_1/2 -^2P_1/2 transition of Sr+ at 422nm. The absorption spectrum is Doppler broadened, which gives a measure of the ion velocity. The expansion is driven by the electron pressure, and the ion acceleration gives a measure of the electron temperature. We hope to stud...

Ultracold plasmas are produced by laser ionization of ultracold atomic gases. Since these plasmas are created in a disordered state, the buildup of spatial correlation leads to rapid electron and ion heating^1. With optical absorption imaging and Doppler spectroscopy on the ions, we are able to measure the ion kinetic energy^2. We perform systemati...

We report optical absorption imaging of ultracold neutral strontium plasmas. The ion absorption spectrum determined from the images is Doppler broadened and thus provides a quantitative measure of the ion kinetic energy. For the particular plasma conditions studied, ions heat rapidly as they equilibrate during the first 250 ns after plasma formatio...

We create ultracold neutral plasmas by ionizing laser-cooled strontium near the ionization threshold. The energetics of the plasma is determined entirely by the photoionization process, and we find the initial electron energies range from 1-1000 K. The ion densities in the plasma can be as high as 10^10 cm-3. These systems have traditionally been s...