About Me
I am an early career researcher in the group of Ralf Metzler at the University of Potsdam, Germany, where I also did my PhD in theoretical physics and graduated with summa cum laude ("highest honours"). Before that, I graduated with a master degree from the Technical University of Dresden, Germany, and there worked in the group of Abhinav Sharma at the Leibniz Instituite for Polymer Research.
My research lies at the intersection of statistical physics, soft matter theory, and nonequilibrium dynamics, with a focus on understanding how broken symmetries and interactions shape transport processes in complex systems.
A central theme in my work is the role of antisymmetric (odd) transport tensors, which arise in systems with broken time-reversal or parity symmetry, such as active chiral matter or particles under Lorentz-like forces. I investigate how these symmetry-breaking effects manifest in both equilibrium and nonequilibrium settings, from microscopic stochastic models to coarse-grained field theories.
I am always interested in collaborating with fellow researchers and discussing new ideas. Feel free to reach out if you'd like to connect!
Last updated: February 2026
Research Areas
Tracer transport in odd systems
Transport in soft matter is fundamentally altered when time-reversal and parity symmetries are broken. We investigate how such symmetry breaking, encoded in odd transport coefficients, modifies tracer dynamics in interacting particle systems. We focus on how interactions in odd-diffusive media, both passive and active, lead to enhanced or even reversed tracer motion. Recent results demonstrate that repulsive collisions can enhance tracer diffusion and, remarkably, cause a reversal of Hall-like drift under force, effects that are absent in symmetric environments, or believed to characterise actiuve systems. This research contributes to a growing understanding of how chiral fluids, skyrmionic media, and other non-reciprocal systems process fluctuations and respond to external driving, revealing new directions for controlling microscopic transport.
Chiral field theories
How does chiral symmetry breaking affect collective behavior in many-body systems? This line of research develops field-theoretic frameworks to describe nonequilibrium dynamics in chiral and active matter. Building on Dean-Kawasaki-type equations or the Active Model B+, we incorporate antisymmetric couplings, originating from odd diffusion and chiral activity, into fluctuating hydrodynamic theories. These approaches reveal how chiral interactions affect density fluctuations, pattern formation, and macroscopic transport coefficients. This work aims to connect microscopic stochastic dynamics to emergent continuum descriptions in systems ranging from colloidal suspensions to biological swarms with internal rotation or handedness.
Odd diffusion on the lattice
How to incorporate chirality on a discrete setting? In this project we develop the "Chiral Random Walk" (CRW) as a minimal lattice model for odd diffusion. By equipping a classical walker with an internal degree of freedom and a tunable chirality parameter, the model interpolates between standard Brownian motion and a deterministic, topologically nontrivial limit. This framework reveals that the robust edge currents observed in chiral fluids and odd-diffusive media can be traced back to a discrete bulk–boundary correspondence. Even in the presence of dissipation and disorder, boundary modes remain parametrically more persistent than bulk transport. The CRW thus provides a microscopic bridge between stochastic dynamics, odd transport coefficients, and Floquet-type topology, offering a platform to study confined geometries, heterochiral interfaces, and transport in complex media.
Projects
History of diffusion and chirality
Originating in my PhD thesis, this project traces the conceptual development of Brownian motion from its classical origins to its modern generalizations in chiral and non-equilibrium systems. By combining historical analysis with theoretical insight, it explores how ideas of symmetry, irreversibility, and stochastic dynamics have evolved; culminating in today's understanding of odd transport phenomena. Special emphasis is placed on how chirality entered statistical physics and how its interplay with Brownian motion reshaped foundational notions of diffusion, mobility, and fluctuation-dissipation. The goal is, that this work will eventually culminate into a topical review article that I am invited to write for the Journal of Physic A.
Publications
News & Updates
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!
Impressum & Contact
Information according to § 5 TMG
Erik Kalz
University of Potsdam
Institute for Physics & Astronomy
Karl-Liebknecht-Straße 24/25
14476 Potsdam
Germany
Contact
Email: erik.kalz@uni-potsdam.de
Responsible for content
Erik Kalz
Address as above
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