The BIPM and Tsinghua University (China) signed a Letter of Intent for a joint technical cooperation in the area of Kibble balance development on 28 August 2024. This newly created agreement was signed by the Director of the BIPM, Dr Martin Milton, and the Vice-President of the Tsinghua University, Prof. Zeng Rong.

The objective of this important collaborative agreement is to formalize the existing mutual support between the two parties towards the development of a future generation of Kibble balances. These devices allow the realization of the definition of the kilogram based on the Planck constant.

The BIPM will provide advice to Tsinghua University on the general design and operation of Kibble balances and in particular on the design of the optical subsystems. Tsinghua University has provided the BIPM with a compact magnetic circuit based on an original BIPM design but incorporating innovative features. The magnet design will become a part of a table-top Kibble balance under development at the BIPM. Tsinghua University will provide the BIPM with advice on matters related to magnetism.

The cooperation was facilitated by Dr Shisong Li, who worked as part of the BIPM Kibble balance team from 2016 to 2019 and who started work at Tsinghua University in 2021. The Vice-President of Tsinghua University visited the BIPM for the signing of the Letter of Intent, accompanied by a delegation of four of the University’s department directors.