Anyons as a New Link Between Superconductivity and Magnetism
Superconductivity and magnetism have been considered almost incompatible states of matter in physics for decades. In the classic textbook representation, a superconductor expels a magnetic field from its interior, while magnetic disorder in a material breaks the fragile electron pairs responsible for superconductivity. However, during 2025, two independent experiments showed that these two seemingly opposing worlds can indeed meet in the same material. It is precisely on this riddle that a team of theoretical physicists from the Massachusetts Institute of Technology (MIT) is now building its explanation, introducing exotic quasiparticles – anyons – into the game.
The new work by MIT physicists, published on December 22, 2025, in the journal Proceedings of the National Academy of Sciences (PNAS), proposes that in two-dimensional magnetic materials, electrons can "fragment" into fractions of themselves and, in the process, form anyons. At certain charge ratios, these anyons, according to the theory, can begin to flow without resistance while maintaining the material's magnetic order. In other words, superconductivity in these systems could arise not due to the usual Cooper pairs of electrons, but as a collective motion of fractionated quasiparticles.
Two Unexpected Occurrences in Graphite and MoTe2
The impetus for the new theoretical work came from recent experimental discoveries. In May 2025, Long Ju's team from MIT announced that in a particularly complex version of graphene, so-called rhombohedral graphene composed of four or five layers, they found a material that is simultaneously a superconductor and a magnet. In this system, at very low temperatures, electrons form a so-called chiral superconductor: electron pairs conduct current without resistance, but at the same time, their orbits carry a magnetic moment, so the entire material behaves as a kind of superconducting magnet.
Almost at the same time, other research teams, mostly associated with Princeton University and collaborating institutions, studied the conditions under which topological quantum states arise in a twisted bilayer of the semiconducting crystal molybdenum ditelluride (twisted bilayer MoTe2). In such moire structures, the appearance of the fractional quantum anomalous Hall (FQAH) effect had already been confirmed, in which electrons do not need an external magnetic field at all to organize into a topological state with a fractionated charge.
New results from 2024 and 2025 added another surprising element to this picture: in the same parameter range where the FQAH effect appears, superconductivity signals were also recorded in the twisted MoTe2 bilayer. Some measurements even suggest that when doping states with an effective charge density of approximately two-thirds of the electron charge, the integer quantum anomalous Hall effect reappears, surrounded by a narrow region of superconducting behavior. It is precisely this combination of magnetism, topological order, and superconductivity that suggests the fundamental "working unit" in these materials could be fractionated quasiparticles – anyons.
The Third Type of Particles: What Are Anyons Actually?
In standard particle zoology, nature knows two large "families" of particles: bosons and fermions. Bosons, the most famous of which is the photon, love to share the same quantum states; they can pile up in the same place in space and at the same energy level, enabling phenomena like laser light or Bose–Einstein condensates. Fermions, such as electrons, protons, and neutrons, behave quite the opposite: due to the Pauli exclusion principle, each combination of quantum numbers can belong to only one fermion, so they "push" each other and avoid one another.
Anyons form a third, much more exotic class. They appear only in two-dimensional systems, such as ultrathin layers of material or moire structures, where quantum mechanics allows a completely different type of statistics. While the exchange of two fermions or bosons is reflected only in the sign of the wave function, the exchange of anyons can add an arbitrary phase to the wave function. It was precisely because of this freedom of behavior that Nobel laureate Frank Wilczek proposed the name "anyon" in the 1980s – because, in principle, "anything goes."
Anyons are not just mathematical curiosities. In fractional quantum Hall states, which occur in two-dimensional electron gases under a strong magnetic field, charges carrying only a third or even a fifth of the elementary electron charge have been experimentally detected. Such fractionated quantum states are interpreted as collective excitation forms – anyons – that arise from the complex correlation of many electrons.
In recent years, similar states, but without an external magnetic field, have been discovered in moire materials, especially in twisted MoTe2. There, the FQAH effect appears thanks to the topological properties of so-called Chern bands and spontaneous ferromagnetism, so it is assumed that anyons with a fractionated charge also appear there. This opens the possibility of studying and manipulating anyons in solid matter under significantly more "practical" conditions than in classic experiments on semiconductor heterostructures.
An Old Idea of Anyonic Superconductivity Gets a New Chance
The idea that a collection of anyons could become a superconductor is not new. As early as the late 1980s, theorists like Robert Laughlin and Wilczek himself considered scenarios in which anyons, under the influence of magnetism, organize into a collective state without resistance. However, these works long remained at the level of elegant but experimentally unreachable models: the link between magnetism and superconductivity seemed too unlikely, and a concrete material in which such a state could appear simply did not exist.
A series of discoveries in rhombohedral graphene and twisted MoTe2 overturned that picture. In graphite, MIT experimentalists showed that a chiral superconductor that behaves like a magnet occurs in five-layer rhombohedral graphene, even though classic superconductors repel magnetic fields. In MoTe2, other teams, combining transport and microscopic measurements, found conditions where superconductivity appears alongside or immediately next to the FQAH state. Thus, the magnetic-superconducting "impossible trinity" has become an empirical fact, not just a theoretical dream.
This is where Senthil Todadri and his doctoral student Zhengyan Darius Shi enter the story. Their PNAS paper starts from the assumption that the FQAH state in MoTe2 is a good starting description of the downstream phases that arise by doping – inserting additional charge carriers into the system. Every new electron that enters such a topological insulator can, due to strong correlations and topological order, "fragment" into several anyons with a fractionated charge. The question is: how can this dilute gas of anyons organize itself at very low temperatures?
Frustrated Anyons and the Critical Role of Charge 2/3
The authors use the mathematical apparatus of quantum field theory and effective Chern–Simons theories in their model to describe the interaction of anyons in a two-dimensional lattice. A key result is that, depending on the density of doped electrons, two types of anyons appear in the system: some with a charge of approximately e/3, and others with a charge of around 2e/3, where e is the elementary charge of the electron. Each of these fractions also carries a specific "statistical" interaction – a quantum mechanical phase factor that determines how anyons feel as they pass by each other.
When anyons with a charge of e/3 dominate the system, their mutual statistical repulsion leads to strong quantum frustration. Every attempt by any anyon to move through the lattice meets "resistance" from the entire collective; the system remains in a kind of metallic phase in which current flows with a finite, though unusual, resistance. The image is similar to an ordinary metal, only instead of electrons, the main role is played by fractionated quasiparticles.
The situation changes dramatically when anyons with a charge of 2e/3 prevail. In this regime, as the model shows, statistical interactions between anyons can be effectively "canceled out" in a way similar to how magnetic fields are canceled in a superconductor. The result is a collective state in which anyons organize into a coherent quantum liquid – an anyonic superconductor. Although this is a completely different microscopic mechanism than in a conventional BCS superconductor, the mathematical description can be translated into the language of "Cooper pairs of anyons," which somewhat retains the intuition of common superconductivity theory.
Another intriguing detail of the theory is the prediction that anyonic superconductivity does not appear homogeneously at its onset. Instead of a neat, spatially uniform superconducting phase, the model proposes an arrangement of vortex supercurrents that arise spontaneously in random pockets within the material. Such "spotted" superconductivity, linked to the topological properties of the substrate, would be a clear experimental signature that anyons, and not just unusual pairs of ordinary electrons, are indeed active in the background.
Toward a New Phase of Matter: Anyonic Quantum Matter
If it turns out that this exact mechanism is responsible for the appearance of superconductivity in twisted MoTe2 – and perhaps in other moire materials – physics will gain a completely new class of matter phases. Todadri calls this hypothetical regime "anyonic quantum matter": states in which the basic charge carriers are no longer the electron or the hole, but collective fractionated objects with unusual statistics. In such materials, magnetic order, the topological Hall effect, and superconductivity would not be separate phenomena, but manifestations of the same, deeper quantum order.
Already now, there is a whole range of theoretical works trying to map possible phases resulting from doping FQAH insulators, including topological superconductors with Majorana edge modes and so-called pair-density-wave phases in which the amplitude of the superconducting pair density is spatially modulated. The new MIT work on anyonic superconductivity logically follows that line of research but stands out by attempting to directly link specific experiments in MoTe2 with the dynamics of fractionated excitations.
In parallel with this theoretical development, experimentalists are getting better at controlling the conditions in moire structures. In twisted MoTe2, it is now possible to very precisely tune the twist angle, carrier density, temperature, and external fields, which opens space for targeted tests of the anyonic scenario. For example, spatially resolved measurements of supercurrents could check whether local "puddles" of superconductivity that the model predicts actually exist, while sensitive magnetometry could detect the simultaneous topological magnetic response.
Anyons and the Quest for Stable Quantum Bits
Although the current focus of Senthil Todadri's and Zhengyan Darius Shi's work is on explaining specific experiments, the broader motivation is clearly connected to quantum computers. Anyons – especially those with non-linear, so-called non-Abelian statistics – have long been considered ideal candidates for stable quantum bits. Information in such systems would be stored not in the local state of an individual particle, but in the global topological order of a collection of anyons, which naturally protects the quantum state from local disturbances.
If it turns out that it is possible to reproducibly create anyonic superconductors in moire materials, researchers would obtain a long-desired platform for so-called topological quantum computing. In such a scenario, logical operations would not be performed by a classic pulse on a single "qubit," but by the slow, geometrically defined "braiding" of anyon paths around each other. The topological nature of this process makes the results extremely robust to noise and imperfections, which is one of the main challenges of today's quantum technology.
For now, however, it is just a promising theoretical step. The authors themselves point out that numerous additional measurements are needed before their picture can be confirmed or refuted. It is particularly important to distinguish the contribution of anyons from possible exotic phases of ordinary electrons, which often produce unexpected behaviors in two-dimensional topological bands. But the fact that we are no longer talking about purely speculative scenarios, but about a theory anchored in concrete experiments, makes this story one of the most exciting in contemporary solid-state physics.
What Follows After the First Theoretical Indications?
In the months and years following the publication of the MIT work, a close dialogue between theory and experiment is expected. Various groups have already proposed alternative models of anyonic superconductivity in doped FQAH states and detailed the transitions between the superconducting phase and re-entrant quantum anomalous Hall insulators in twisted MoTe2. The key will be to identify measurable quantities – such as a specific pattern of vortex currents, uneven charge density, or unusual edge modes – that uniquely distinguish the anyonic scenario from competing explanations.
Regardless of the outcome, it is already clear that the new discoveries of "magnetic superconductivity" in rhombohedral graphene and the combination of the FQAH effect and superconductivity in MoTe2 have opened a completely new phase of quantum matter research. The boundary between magnetism, topological insulators, and superconductors is no longer as rigid as it once seemed. In this new overlap zone, anyons are emerging as the natural language in which future experiments and theories will likely be written.
If it turns out that "anything-goes" anyons are indeed the foundation of a whole series of unexpected quantum phenomena, from laboratory moire structures to potential new materials, physics will gain not just another exotic addition to its encyclopedia, but a concrete tool for building more robust quantum technologies. The road to such applications will be long and full of uncertainty, but the latest results show that at least the first, conceptually crucial step has just been taken.
Sources:
- MIT News – Anything-goes “anyons” may be at the root of surprising quantum experiments (link)
- MIT News – MIT physicists discover a new type of superconductor that’s also a magnet (link)
- Nature – Signatures of fractional quantum anomalous Hall states in twisted MoTe2 bilayer (link)
- Science Advances – Anomalous superconductivity in twisted MoTe2 nanojunctions (link)
- Anyon delocalization transitions out of a disordered FQAH insulator – arXiv preprint (link)
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