MIT-FAPESP research collaboration on superfluids

Scientists with research supported by the institutions talk during FAPESP Week about the importance of partnerships for the development of Physics and other fields.

"No one conducts science all alone. For cutting-edge research, partnerships with researchers from other institutions and countries are very important. And the Massachusetts Institute of Technology (MIT), which has always prided itself on attempting to solve sciences’ greatest challenges, is one of the best partnerships we could ever dream of having,” says Vanderlei Bagnato, Professor at the São Carlos Institute of Physics at the University of São Paulo (USP), in the symposium at MIT held October 22, 2012.

The symposium in Cambridge, Massachusetts was one of the activities featured as part of FAPESP Week 2012, which began in Toronto, Canada. It will be followed by events at the Woodrow Wilson International Center for Scholars in Washington, DC and the University of West Virginia in Morgantown.

At the symposium, Bagnato spoke about the collaboration he has had with MIT scientists since he completed his PhD. in Physics there in 1987. This collaboration grew even more in 2012 when he began a research project to study atomic fluids with his group at USP together with the team headed by Professor Wolfgang Ketterle, Director of the MIT-Harvard Center for Ultracold Atoms and winner of the Nobel Prize in Physics in 2001. 

The research project was funded by FAPESP and MIT and selected in a call for proposals issued within the scope of a cooperation agreement between the two institutions. 

The scientific challenges for the teams of Bagnato and Ketterle are on the cutting-edge of physics research, in a little known area that involves terms such as superfluidity, superconductivity and Bose-Einstein condensate that are interrelated.

Superfluids represent a state of matter in which the matter behaves like a fluid with zero viscosity. The phenomenon, which occurs at extremely low temperatures - thus, the reason for referring to cold, supercold or ultracold atoms – was discovered in 1938 in liquid helium and has applications in astrophysics, high-energy physics and quantum theories. 

An example of superfluidity is the Bose-Einstein condensate, which is a state of matter formed by atoms at temperatures near absolute zero that allow quantum effects to be seen on a macroscopic scale. Albert Einstein predicted the existence of the Bose-Einstein condensate in 1925, based on the work Satyendra Nath Bose, as a theoretical consequence of quantum mechanics.

Seventy years later, Ketterle and two scientists from the University of Colorado, Eric Cornell and Carl Wieman, produced the condensate for the first time, a feat that led to them to the Nobel Prize in Physics in 2001.

A superfluid has properties similar to ordinary liquids and gases, like the lack of a definite shape and the capacity to move in response to forces applied to it. But a superfluid also has properties that are not present in ordinary matter, such as the ability to move at very low speeds without dissipating energy, or in other words, with zero viscosity.

At higher speeds, energy is dissipated through the formation of vortices, a type of hole where superfluidity ends. Turbulence is a phenomenon that occurs in fluids – liquids and gases – generally subjected to completely disorderly movement, the vortices.

In 2009, a study conducted by Bagnato and his group, together with researchers from the University of Florence, Italy, demonstrated that the phenomenon of turbulence also occurs in the Bose-Einstein condensate. The discovery shed new light on the study of the two principal challenges of contemporary physics: the phenomena of turbulence and superfluids. The study was published in the journal Physical Review Letters.

“The Bose-Einstein condensate becomes a fluid when it is subjected to a temperature near absolute zero,” says Bagnato, who runs the Optics and Photonics Research Center (CePOF) of São Carlos, one of the Research, Innovation and Dissemination Centers (RIDC) funded by FAPESP.

"In order to research the phenomenon of turbulence in quantum fluids and superfluids, collaboration with personnel from MIT will be critical, since they have great experience in the subject. And they are researchers whose scientific concerns are similar to those in our group in Brazil,” says Bagnato.

Ketterle was not able to take part in the FAPESP Week symposium, but MIT was represented in a session on cold atoms by Daniel Kleppner, Professor Emeritus of Physics at the Institute.

"Brazil is a remarkable country in many aspects, and certainly one of them is the existence of important programs that fund basic science, such as those offered by FAPESP. Conducting research in a cutting-edge area like super-low temperature physics is quite difficult, and we’re very happy to be able to collaborate with Brazilian colleagues engaged in such important work in this field like the CePOF group in São Carlos," says Kleppner.