Strongly interacting quantum particles are key to some of the most fascinating phenomena in modern physics—from magnetism and superconductivity to topological states. Yet the complexity of such systems makes many of their properties difficult to understand even today. A research team from Innsbruck and Turin has now proposed a new theoretical framework for generating and studying these exotic states of matter on ultracold magnetic atoms in a one-dimensional lattice.
A new quantum model for magnetic atoms
At the heart of the study is a specially designed theoretical model, a well-established framework in quantum physics used to describe the behavior of strongly interacting quantum particles called fermions. The researchers developed a realistic experimental setup based on ultracold magnetic lanthanide atoms, specifically Erbium and Dysprosium, trapped in a one-dimensional optical lattice. Thanks to the exceptionally large magnetic moments of these atoms, the team was able to construct a system in which three key parameters — how particles move between lattice sites, how their spins interact with one another, and how strongly they repel each other when occupying the same site — can be tuned independently of one another. This level of control goes significantly beyond what has been achievable with conventional atomic systems.
A topological superconductor
Using a combination of analytical methods and advanced numerical simulations the team mapped out a rich phase diagram comprising seven distinct quantum phases. These include several forms of one-dimensional superconductivity, a topological liquid, and notably, a topological triplet superconductor. In this state, superconductivity—that is, the lossless transport of electric charge—coexists with topological order, a quantum state that is robust against environmental noise. “This exotic state of matter, in which topological order and superconductivity are deeply intertwined, has not previously been experimentally realized”, explains lead author Leonardo Giacomelli from the team of Francesca Ferlaino. “Our approach provides a concrete and experimentally accessible platform for this”, adds Luca Barbiero of the Politecnico di Torino.
A path to experimental realization
The researchers have developed a detailed, step-by-step protocol for preparing and detecting all of the predicted quantum phases using quantum gas microscopy techniques. “Our study presents a concrete step toward a deeper understanding of the intriguing states of matter emerging in strongly interacting fermionic quantum matter”, says Francesca Ferlaino. “The proposed platform is directly compatible with existing experimental setups, which is particularly relevant given that topological superconductors are among the most promising candidates for fault-tolerant quantum computing.”
The work has been conducted at the Department of Experimental Physics of the University of Innsbruck and the Institute for Quantum Optics and Quantum Information (IQOQI) of the Austrian Academy of Sciences (ÖAW). It has been published in Nature Communications and was supported by the Austrian Science Fund (FWF), the European Research Council (ERC) and other funding bodies.
Publication: Topology meets superconductivity in a one-dimensional t-J model of magnetic atoms. Leonardo Bellinato Giacomelli, Thomas Bland, Louis Lafforgue, Francesca Ferlaino, Manfred J. Mark, and Luca Barbiero. Nature Communications 17, 5328 (2026) DOI: 10.1038/s41467-026-71248-8