Father of modern atomic physics named honorary professor at Universidade de São Paulo

Daniel Kleppner, of MIT, is honored at an event that brought together five Nobel Laureates and other leaders in the area.

By Karina Toledo

Agência FAPESP – The majority of scientists dedicated to uncovering the mysteries of atoms and quantum mechanics – of subatomic particles – have a certain obsession with reaching extremely low temperatures, increasingly close to the so-called “absolute zero” (0 K on the Kelvin scale, or -273.15°C).

In an interview with Agência FAPESP, the winner of the 2001 Nobel Prize in Physics, Eric Cornell, explains why: “Think of temperature as noise, speaking metaphorically. The lower it is, the quieter it will be. And if it is quiet enough, you can hear nature murmuring its secrets.”

Understanding how quantum mechanics works when thousands of particles interact simultaneously among themselves is one of the great conundrums of this century. Because everything moves more slowly as the temperature decreases, the challenge becomes less difficult if the temperature is close to absolute zero.

Many experiments with this objective conducted over the past few years have been based on work developed by U.S. physicist Daniel Kleppner, one of the founders of the Center for Ultracold Atoms, which brings together researchers from the Massachusetts Institute of Technology (MIT) and Harvard University.

At the end of February, Kleppner received the title of honorary professor from Universidade de São Paulo’s São Carlos Institute of Physics (IFSC-USP), where he has been an advisor for more than 10 years.

The honor was granted during a symposium organized by the São Carlos Optics and Photonic Research Center, one of FAPESP’s Research, Innovation and Dissemination Centers (CEPID), which brought together several of the most renowned scientists in the area.

“Dan has just turned 80 and for a physicist, the best way to celebrate something is organizing a symposium,” joked the 1997 Nobel Laureate in Physics, William Phillips, who is also an honorary professor at IFSC-USP, during the opening ceremony for the event.

Better known in the academic world as Bill, Phillips is a researcher at the National Institute of Standards and Technology (NIST) in the United States, was a student of Kleppner and received the Nobel Prize – along with Steven Chu and Claude Cohen-Tannoudji – for inventing a type of trap to immobilize atoms that uses laser beams and magnetic fields.

The technique allows scientists to reach a temperature six times lower than previously thought possible – approximately 40 millionths of one degree Celsius above absolute zero. “This is four million times colder that the temperature of outer space and 100 million times colder than liquid nitrogen, which is certainly the coldest thing you’ve ever seen,” explained Phillips.

In addition to allowing the development of extremely precise quantum watches – which in turn allowed the creation of Global Positioning Systems (GPS), found in cars around the world – Phillips’ invention also made possible the experiment that guaranteed the Nobel Prize for Eric Cornell, Carl Wieman and Wolfgang Kettere: reaching a state of matter known as the Bose-Einstein condensate (BEC). A BEC is a state of matter in which matter behaves like a fluid with zero viscosity – the so-called superfluid – capable of moving at low speeds without dissipating energy.

The existence of the Bose-Einstein condensate was predicted by Albert Einstein in 1925, based on the works of Satyendra Nath Bose (1894-1974). The experiments conducted by Cornell, Wieman and Ketterle in the 1990s paved the way for research underway at Cepof under the coordination of Vanderlei Bagnato, of IFSC-USP, who worked with Kleppner during his doctorate at MIT.

In 2009, a study conducted by Bagnato’s group in partnership with researchers from the University of Florence in Italy showed that the phenomenon of turbulence – which occurs in liquids and gases submitted to random movements – can also be observed in the Bose-Einstein condensate. The discovery paved the way for a new approach to the two main challenges of contemporary physics: the study of the phenomena of turbulence and superfluids.

Technology of the future

Two other Kleppner collaborators present at the symposium were David Wineland, of NIST, and Serge Haroche, of Collège de France. Both won the 2012 Nobel Prize for research that allowed for the manipulation, analysis and counting of quantum particles without destroying them. Among the promises of new technologies that should emerge as a result of this feat are ultraspeed quantum computers.

“In analyzing the history of technology, we realized that the future is in very small things, or rather, it is in the direction of quantum mechanics,” affirmed Cornell, who is currently a professor at the University of Colorado in the United States.

Among the Nobel Laureates attending the São Carlos symposium to honor Kleppner, Dudley Herschbach of Harvard was the only one making his first visit to Brazil. Herschbach was also an outlier in terms of his area of activity, chemical physics.

Herschbach received science’s highest honor in 1986 for his pioneering experiments with the technique of crossed molecular beams to study chemical reactions and the dynamics of molecule atoms in real time. “But I think I was invited to this symposium in reality because I have been a friend of Kleppner's for more than 50 years, since graduate school,” he explained.

The event program also boasted other illustrious speakers, such as France’s Alain Aspect, a contender for the Nobel Prize for his research in optics. This research facilitated the development of quantum cryptography, a technology that promises to make secret information inviolable and that has subsequently been adopted by several banks.

“I would say that not only all the work of those present, but the majority of what is happening in atomic physics around the world, is in some way connected to Kleppner’s research,” evaluates Phillips.

Although he is considered to be the victim of a grave injustice in the scientific world because he has never won a Nobel Prize despite his role in training so many winners of the honor, Kleppner, nicknamed by Phillips “The Godfather of the Bose-Einstein condensate”, is modest.

“I think that the presence of such an extraordinary audience in Brazil is more of a demonstration of the recognition and respect for the work that has been conducted by Professor Bagnato’s group than a show of affection for me. They can find me any time in the United States,” he joked.