Physicists build supersolid connections between Edmonton and Paris

An international collaboration between the University of Alberta's John Beamish and French physicist Sebastien Balibar is yielding a two-way exchange of ideas and research experience.

Suzette Chan - 12 February 2013

(Edmonton) Last year, Penn State University physicist Moses Chan all but disproved his 2004 experiment that indicated the possibility of a fourth state of matter. His announcement effectively marked the end of supersolidity.

However, the past decade of prolific research in the field found new questions to answer about macroscopic quantum behaviour in solid helium. The research also led to a collaboration between researchers based in Edmonton and in Paris that continues to flourish.

In the hunt for supersolidity, University of Alberta physicist John Beamish started studying solid helium, which was also being studied by French physicist Sébastien Balibar of École Normale Superieure and CNRS in Paris.

Balibar is in Edmonton this week as the Hiroomi Umezawa Memorial Distinguished Visitor. He delivers a public lecture on Tuesday, February 12th at 4:30 p.m. in CCIS L2-190. Everyone is invited to a reception following the talk.

"Sébastien has done fascinating and fundamental work throughout his whole career and has been recognized by essentially every major award in France and in low temperature physics internationally," says Beamish.

"Our research groups both started doing elastic measurements on solid helium, using different techniques," Beamish says. "We managed to build and incorporate my elastic transducers into his optical cells and do a whole series of measurements during the eight months I was there on sabbatical."

Balibar will describe some of the results of this joint venture as part of a Physics colloquium about "giant plasticity " in helium crystals on Thursday, February 14th.

In addition to advancing the pool of knowledge about helium crystals, the collaboration between Beamish and Balibar has opened a two-way exchange between their respective research facilities. Beamish has tested University of Alberta-made sensors and techniques in France, while members of Balibar's group have come to Edmonton to do experiments in Beamish's lab.

Balibar says several factors go into a successful collaboration, including compatible personalities, complementary technical expertise, shared scientific goals and a willingness to exchange ideas freely. Of their current collaboration, Balibar says, "[Beamish] knew methods to measure the elastic properties of matter, which are sensitive and direct. He also had a culture in materials science which I did not have. On our side we knew how to prepare high quality crystalline samples and we had the optical access at the low temperature of our crystals to determine their orientation."

He adds that the complementariness extended to younger members of the research groups.

While Beamish was in Paris, he had his grad student, Syed Bukhari, send him an experimental cell that a postdoc in Balibar's lab modified for new experiments. Beamish returned to Edmonton with Paris postdoc, Andrew Fefferman, to continue the work.

"Together we (Andrew, Syed Bukhari and I) mounted the cell on my refrigerator and did the experiment we'd planned," Beamish recalls. "This was great for me, but also let Andrew do an experiment that otherwise would have taken many months to build and test, and it gave Syed a chance to work with us and learn a new technique."

Beamish's time in Paris also allowed him to work with a grad student named Xavier Rojas, who is now a postdoc at the University of Alberta. Rojas says Beamish "certainly influenced" his decision to come to Edmonton by discussing the new ulta-low temperature lab that was being set up by UAlberta physicist John Davis.

"I decided to come because John Davis is conducting interesting projects that I would like to develop myself in the near future," says Rojas, who is researching the measurement of quantum fluid properties in microfluidics devices, key components in nanotechnology. "I was also interested in being a part of the emergence of a brand new low temperature lab. It is hard to do and I wanted to learn how you can start from the very beginning."

Rojas was also intrigued by Beamish's stories about the "extreme weather" in Alberta: "He also proved it by being the only one wearing a shirt outside in Paris when it was -15°."

Now, another Paris physicist is coming to Alberta. Balibar is bringing his grad student, Ariel Haziot, who did the measurements for the recent work in Paris. Haziot will stay in Edmonton a bit longer to exchange ideas with Beamish and his team.

"We discussed and shared our specific skills and techniques about cryogenics, measurement using piezoelectric transducers, way to grow good quality helium crystals," says Haziot of his work with Beamish in Paris. "In that way, we learned from each other. This quick visit in his group is a very good opportunity to put images and concrete stuff on these discussions."

Beamish says these exchanges will continue. "I hope to spend at least a month or two there in coming years and I think it would be great to give some of my graduate students similar opportunities. France has an extremely strong low temperature physics tradition and it is very valuable to see another research system while you are a student."

Balibar agrees. "Our collaboration is going to extend and deepen. My visit in Edmonton this time is such an opportunity. We have decided to keep visiting each other in order to design and run together a number of other experiments so that we finish understanding every detail of this new phenomenon."

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Q & A with Sébastien Balibar

What is the value of international collaborations like the one you have with John Beamish?

This question is both interesting and important.

What makes a collaboration fruitful? I don't think that there is a big difference between an international collaboration and a national one, except that when it's international it's a nice opportunity to discover a different country with different ways of life. As a scientist I am curious, so discovering something different is always a great pleasure. But if I restrict myself to the scientific aspect of a collaboration, the country of participants makes not much difference.

To be fruitful, or efficient if you prefer, a collaboration probably needs people to be complementary. Each participant needs to bring something original which fits with what the others bring. For a long time I had collaborations with theorists because, as an experimentalist, the chance of being complementary was largest. Even this is not necessarily successful because a theorist and an experimentalist do not necessarily understand each other. Between two experimentalists, we need to know methods or have equipment that are different and can be combined.

In the case of John Beamish and myself it was clear from the beginning that he knew methods to measure the elastic properties of matter, which are sensitive and direct. He also had a culture in materials science which I did not have. On our side we knew how to prepare high quality crystalline samples and we had the optical access at the low temperature of our crystals to determine their orientation. That's why we thought that joining each other would allow us to make breakthroughs in the understanding of what is now known as the "giant plasticity of quantum crystals," a spectacular property of matter.

After a very successful year - the year 2012 - of collaboration in Paris we are convinced that it was indeed a good idea. But I have to add that sharing techniques is not sufficient because scientific research requires that people adapt their respective personalities to each other. One cannot work together, that is share hope and disappointment, anxiety and happiness, without building friendship. This is an opportunity for me to say that John Beamish and his wife Kathy are marvelous people with whom life is a real pleasure.

You see, there are many requirements for a collaboration to be a success, and between John Beamish and myself it worked quite well. I should add that this matching extended to the young members of our respective groups. The clear result is that our collaboration is going to extend and deepen. My visit in Edmonton this time is such an opportunity. We have decided to keep visiting each other in order to design and run together a number of other experiments so that we finish understanding every detail of this new phenomenon, I mean this giant plasticity.

A last aspect of this question might be the difference between real visits, which imply expensive flights, jetlag and so on, and communication through the internet that is cheap and easy. Well, I believe that we need both: the Internet for daily exchange of short news and ideas, the real visits for deeper exchange of arguments, more efficient rewriting of common papers, and so on. For example, having one hour to let our imagination evolve freely while drinking a cup of coffee is something useful that is hardly possible in front of a computer screen.

In summary, a collaboration is not always a success, there are necessary conditions but one is never sure that meeting these conditions will necessary lead to this success, and when it does it's a wonderful experience.