In conventional three-dimensional space, particles belong to one of two categories: fermions or bosons. In low-dimensional settings, however, quantum mechanics allows for more exotic behavior. Here, anyons can emerge—quasi-particles whose exchange properties continuously interpolate between those of bosons and fermions, leading to fractional statistics. Detecting and engineering such particles in one dimension has long been a central challenge, typically requiring, as theory proposal suggest, intricate scattering schemes or density-dependent tunneling processes.
A new study by teams led by Hanns-Christoph Nägerl at the University of Innsbruck and Nathan Goldman at the Université Libre de Bruxelles and Collège de France (CNRS) now introduces a remarkably simple yet powerful approach. The researchers propose an effective “swap” model that leverages the spin degree of freedom of ultracold atoms. By assigning a complex phase to the exchange—or “swap”—of two spins, the system naturally acquires the fractional statistical behavior characteristic of anyons.
The team shows that this mechanism directly imprints itself on the one-body correlations of a single spin component. These correlations reveal the asymmetric momentum distributions predicted for one-dimensional anyons—signatures that remained hidden in conventional bosonic observables. The framework captures the essence of recent experimental observations of anyonization in ultracold gases and provides a route for implementing and probing such phenomena in current laboratory setups.
“By highlighting the central role of spin-exchange processes, the work opens new perspectives for exploring many-body anyonic physics and deepens our understanding of exotic quantum behavior in low-dimensional systems”, summarizes Hanns-Christoph Nägerl.
Publikation: Anyonization of bosons in one dimension: an effective swap model. Botao Wang, Amit Vashisht, Yanliang Guo, Sudipta Dhar, Manuele Landini, Hanns-Christoph Nägerl, Nathan Goldman. Phys. Rev. Lett. 2025. DOI: 10.1103/2np8-mp39