The award is an initiative of the Dutch Physics Council. The award is named after Paul Ehrenfest and Tatiana Afanassjewa because of their exceptional ability to stimulate young researchers to leave the beaten path. Xiaofei will receive a bronze statue and € 5,000, to be spent freely. The Ehrenfest-Afanassjewa physics thesis award will be awarded during the NWO Physics conference in Veldhoven on 21-22 January 2025.

The PhD thesis of Xiaofei Guo is entitled “Non-orientable mechanics”. It can be found at: https://pure.uva.nl/ws/files/169556735/Thesis.pdf.

The jury report states: The jury highly appreciates her thesis, which is very well written, clear, and pedagogical. Additionally, Xiaofei presents a unique combination of rigour, enthusiasm, and hard labour. Altogether, this has resulted in impactful breakthroughs in the field of topological physics and metamaterials, in particular on non-orientable mechanics.

In her PhD, she has constructed four completely distinct experimental setups, each with their distinctive technicalities and set of tools. The jury recognizes this as an impressive achievement, as designing these concepts is regarded to be very difficult and requires originality. She designed the experimental and numerical protocols and performed the experiments and bridged her results with the theory. She also systematically redid the theoretical calculations in order to make sure she fully understood and with that she has identified some unclarity or even mistakes. With her research, she discovered a new facet of topological mechanics that uses the concept of non-orientability to classify and exploit geometrical frustration. She has further generalized these results to 2 dimensions and followed up on this work by applying the concept of non-orientable response to active metamaterials. Additionally, she has investigated the mechanical properties of topological insulators with topologically protected floppy modes. The groundbreaking results of applying the concept of non-orientable response to active metamaterials and her work on chiral polarization is very relevant for adaptive soft robotics and for designing topological zero modes respectively.

Since December 2023, Xiaofei has joined AMOLF as a postdoctoral researcher working on optomechanical computation in the groups of Ewold Verhagen and Marc Serra Garcia.

The jury was very pleased with the high level of the nominations and, in addition to the winning dissertation, gave honorable mentions to Rui Yang (UT) and Lukas Veldman (TUD).