2DK Lab

We realized a loss spectroscopy to find the position of the Feshbach resonances in 39K atoms trapped by a crossed optical dipole trap (ODT). The Feshbach resonance technique allows to change the atomic interactions by coupling the energy of a pair of colliding atoms in an initial open channel to the energy of a bound-state in a closed channel by appying a constant magnetic field. Therefore, the scattering length, governing the atomic interaction at low temperatures, diverges in the vicinity of a resonance and the atomic cloud suffers from strong three-body losses, making it possible to identify the position of the resonance by looking to the decrease in the atom number as it is displayed in the graph.

Being able to tune the atomic interaction of 39K atoms is crucial to cross the Bose-Einstein condensate (BEC) critical point, since we should change the value of the scattering length from negative (effective attractive interactions) to positive (repulsive interactions) to produce a stable BEC.

Producing a quantum gas relies on a series of experimental steps which are important benchmarks for the evolution of the experiment. Today, we were able to transfer the atoms pre-cooled with laser light to an Optical Dipole Trap realized with a focused laser beam far red-detuned from the atomic transitions.

We used about 20 W of infrared laser at 1064 nm focused to a beam waist of ~150 um. We trap ~2e6 atoms at some tenths of microkelvin.

During the second semester of 2024 we were happy to have Diana and Mayerlin working with us.

Diana Del Mar Muñoz Valencia was an internship student from Colombia selected at the program for last-year students from IFSC. Mayerlin Nuñez Portela  was a visiting professor from Universidad de los Andes in Bogotá.

From left to right: Gabriel, Lucas, Mayerlin, Diana, Pedro and Patricia.

Our 3D-MOT is shining at the science chamber!

This shinning ball in the center of the glass cell is our 3D magneto-optical trap (MOT) loaded with atoms pre-cooled by a 2D-MOT that pass through a thin tube and travel about 50 cm in vacuum before being recaptured.

The red color is due to the light used to perform the MOT which is resonant with the D2-line atomic transitions of 39K at 767 nm.

The project proposed by our PI, Patricia C. M. Castilho, titled was just selected in the 7th Call for Science from the Serrapilheira Institute, in Brazil.

The Serrapilheira Institute is a private, non-profit institution that promotes science in Brazil. The Calls for Science's mission is to finance scientists who seek excellence in their research, asking fundamental questions, with the risk and dream of offering great contributions to their areas of activity. This year Call had 487 proposals from all fields and only 20 were finally selected.

Our project titled "How the presence of dissipative mechanisms affects the superfluid properties of a quantum system?" aims to use planar ultracold gases to study the dynamics of vortices in superfluids and phenomena similar to those observed in type-II superconductors.

We opened our laboratory!

After a quick renovation, we took the optical tables to a room that was still empty, but full of potential. Our team is excited to transform this space into a real quantum gas laboratory.

We thank everyone who helped and supported this achievement. Now, let's just start assembling!

The digital micromirror device (DMD), composed of an array of 13.7 µm square micromirrors that can be controlled independently by reflecting or not reflecting light in the direction of the atomic cloud, can be used to generate static and dynamic images. In the 2DK Lab, static images will be used to create the two-dimensional trapping potential while dynamic images can be used as perturbations or to transfer angular momentum by stirring the atomic cloud. On the left we show an animation of the laser profile reflected by the DMD in which we see a circle rotating within a dark square-shaped region. This is an example of an animation that can be used to “rotate” the atomic cloud.

Our project was one of the 111 projects selected at the FAPESP call for "Projeto Inicial" (PI) (see the complete list here).

The "Projeto Inicial" research grant is intended to support research projects from young researchers with excellent potential pursuing ambitious results favoring the establishment of a successful research and teaching career.

Our project title “Quantum hydrodynamic instabilities in two-dimensional Bose gases” proposes to explore the onset and evolution of different quantum hydrodynamic instabilities analogous to those in classical fluids, such as the Rayleight-Taylor and the Kelvin-Helmholtz instabilities, as a tool to better understand the superfluid properties of 2D Bose gases.