Erik Kalz

New Postdoc: Beginning of October, I started my new postdoctoral position in the (experimental) lab of Cyriaque Genet at the Laboratoire des nanostructures of Thomas W. Ebbesen at the University of Strasbourg, France. Cyriaque is investigating in his group the role of thermal and external fluctuations on colloidal particles in an optical tweezer setting, and starts to focus on the special role of chirality there. This extraordinary coincidence and their beautifull group athmosphere were reason enough for me to take up this position, even though it will only be for 6 month (stay tuned for the reason:D).

Heimspiel Wissenschaft: I was delighted to return to my home town for a special outreach talk as part of the outrech format "Heimspiel Wissenschaft". I talked about the "Physics of the moderately small" – how concepts from theoretical physics can help us understand everything from bacteria and bird flocks to human crowds. It was a particularly nice experience to share my research back home, where my journey into physics began, and discuss what they can actually tell us about the world around us.

New preprint: We continued our work on the "Chiral Random Walk". Together with Joshua Uhlig and Ralf Metzler from Potsdam, as well as Jan Wójcik from Gdańsk, we are quantifying the effect of chirality-enhanced diffusion in heterogenous media, suggested previously by us. The characteristic chiral edge flow is identifyed as a a geometric "edge-adhearing" mechanism in porous media. Too strong chirality results in circulating behaviour and too weak chirality basically does no change: it is mediocre chirality that enhances the diffusive spread and which is optimal for fast target-search.

Conference season: I will present my work on three workshops and conferences this month: First, I am deeply honoured to speak about the unusual transport in odd systems at a workshop in the Weierstrass Institute in Berlin, on the occation of Arkady Pikovsky's birthday. Further, towards the end of September, I travel to Italy to present our work on the "Chiral Random Walk" in a poster on the 39th M. Smoluchowski Symposium on Statistical Physics in Rome, followed by an invited "emergend talent speaker" at the Venice meeting on Fluctuations in small complex systems VIII.

Michelson Price: I am deeply honoured to recieve the "Michelson Price" of the Faculty of Science of the University of Potsdam for the best doctoral thesis of the year 2025. I share the price with Dr. Leonna Szangolies from the "Plant Ecology and Nature Conservation" group at the UP.

Seminar tour in France: I am visiting Paris and Bordeaux for a series of seminars. Starting by visiting the labs of Sophie Marbach and Raphaël Voituriez, at the Sorbonne University, I am continuing to present my work at the Insitute Curie, invited by Jean-François Joanny The trip concludes with a seminar at the University of Bordeaux, hosted by David Dean. With temperatures hovering around 40 °C, I am grateful that seminar rooms are typically equipped with projectors, though not always with air conditioning.

PRE Letter: We published our work on the reversal of ordinary and Hall drift of a chiral tracer as a Letter in Phys. Rev. E. Combining analytics and numerical simulations my collaborators Shashank Ravichandir from the Leibniz Insitute for Polymer Research in Dresden, together with his PhD supervisor and my long-term collaborator Abhinav Sharma, and my PhD supervisor Ralf Metzler, together we could show that an odd (passive!) tracer shows effect reminiscent of absolute negative mobility in an interacting system. I am especially proud, as this project originated from the supervission of my first Bachelor student in Potsdam: Johannes Birkenmeier.

DPG SKM contribution: My collaborator Jan Wójcik presents our joint work on the Chiral Random Walk at the conference of the German Physical Society (DPG), Section Condensed Matter (SKM) that takes place in Dresden this year to a wide audience. At the same conference, my collaborator Filippo Faedi speaks about our recent joint work on transport anomalies in chiral fluids. How great, to be represented that well!

New preprint: Our preprint on a unified, mobility based approach to transport anomalies in chiral fluids appeard on arXiv. Teaming up up with Filippo Faedi and Abhinav Sharma, my long-term collaborator from Augsburg University, as well as my PhD supervisor Ralf Metzler, we revisited the problem of an odd colloidal tracer. Performing an (analytical) rheology experiment, we can rederive the known transport anomalies in chiral/odd fluids and put them on a joint footing: odd mobility drives an inversion of a density wake around a driven tracer, that eventually leads to enhanced self-diffusion and negative mobility in these systems.

New preprint: Our preprint on modelling the "Chiral Random Walk" (CRW) is on arXiv. Teaming up up with Jan Wójcik, whose expertise is in quantum (random) walks, we found that to correctly capture an odd-diffusive random walk, we have to employ the concept of an internal degree of freedom; a common tool in quatum walks. We were able to write a model that interpolates between the classical CRW and a quantum walk in the limit of large chirality. We could, therefore, harnest the language of toplogical quantum transport to explian the appearenace of edge states in the quantum limit, that persist into the dissipative regime. Commonly observed "edge states" in odd systems, thus, can be understood from a topological perspective. The CRW further is numerically easy to implement, specifically also for complex geometries and heterogenous settings.

Short-term postdoctoral fellowship: I was granted with a postdoctoral exchange fellowship to spend 3 month, from January to April 2026, in the lab of Yael Roichman at Tel Aviv Univeristy, Israel.

PhD defense: I successfully defended my doctorate in theoretical physics with summa cum laude ("highest honours") and now am officially a Dr. rer. nat..

Invited talk at Tel Aviv University: I am delighted to be invited to give a "Physical Chemistry Seminar" at Tel Aviv University, Israel.

Guest editing NJP focus issue: Together with Ralf Metzler and Abhinav Sharma, I am guest-editing a New Journal of Physics 'Focus On' issue on "Broken symmetries and odd transport in statistical physics". Submission deadline is 31st of July 2026. Scope and details on the submission procedure can be found through the Link.

IOP Impact Award: My paper "Field theory of active chiral hard disks: a first-principles approach to steric interactions" has been selected for the celebratory collection of articles published by IOP through the German transformative agreement in 2024 "for the great impact [the papers] have achieved in such a short period of time".

Website Launch: Excited to launch my new research website as I am about to begin my independent career!