It has been six years since I first met Prof. Gao Bo，from the Technical Institute of Physics and Chemistry (TIPC) of the Chinese Academy of Sciences，at a Tempmeko conference in Portugal.

During the conference we discussed many academic issues and I was impressed by her great passion for low-temperature metrology. That’s why I invited her to work in my lab for a few months, which was the beginning of our cooperation. She later participated in research projects measuring the Boltzmann constant and acoustic gas thermometry which have achieved world-leading results. At the same time, we jointly developed a novel primary thermometry at low temperature called single pressure refractive index gas thermometry (SPRIGT). It is expected to become widely used due to its high accuracy and high measurement speeds.

I was very indecisive when Bo first told me she wants to implement this method in China. On the one hand, I believe that the SPRIGT method has great potential and also would promote the entire low-temperature metrology field. On the other hand, the cooperation meant I would have to travel between Paris and Beijing many times which would be a great challenge for me. In addition, at that moment there were no other members on Bo’s team and it would be hard for just us two to implement SPRIGT. Finally, I was persuaded by her passion and ambitions, and now two years of cooperation have proved that my decision was right.

The whole research process of SPRIGT was challenging. We started from an empty room in Langfang which is 70 km from Beijing and lacks international accommodation. When I first got there, there were only some equipment boxes in the empty lab. In the past two years, I have been to China 12 times, and eventually received funding from PIFI.  Every time I have gone to the lab since then I have found many changes and a lot of progress. The young team works seven days per week and has almost no holidays. Because of jet lag, sometimes I went to the lab at two or three in the morning, and there were always some students there. In the spring of this year, in order to get the data of SPRIGT before the deadline of Tempmeko and to realize China’s break-through in this field, they even worked 24 hours per day for four months.

Working with this young and passionate team, I feel that I  was getting younger again. With their hard work they completed the whole process of equipment purchase, installation and experiments, with good results. Together we push the instruments to their performance limit and improve our knowledge of low-temperature metrology. Now the team is growing fast and will continue to face and overcome the various unknown difficulties in the future, contributing more to further research.

Laurent Pitre

Laurent Pitre is a Researcher at the French Metrology Organization LNE-CNAM since 2000. He holds a Phd in Low Temperature Thermometry - below 1 Kelvin (1999), and has started his career with the European project “Ultra Low Temperature”. He has worked for 2 years at the National Institute of Standards and Technology (NIST), Washington D.C. as a Guest Researcher, where he has started to conceive and develop a quasi spherical resonator applied for low temperature thermometry (2003-2005). Since his return to France, he has continued the development and the fine-tuning of the quasi spherical resonator. Today he leads a team, which uses this resonator for the re-determination of the Boltzmann constant and the thermometry in the range of 4K to 300K.

Laurent is a very enthusiastic expert in this research field. He has paid a lot of attention to us and to SPRIGT’s results. All team members are moved by his professional dedication. Meanwhile, he is a scientist who has long-term vision for the future. We have not only established the TIPC-LNE Joint Laboratory on Cryogenic Metrology Science and Technology but also formulated our research plans for more than ten years. With the redefinition of the new SI, an international system of units, world temperature metrology will open a new door. We look forward to continuing cooperation between China and France to jointly promote the development of the frontier science of metrology.