Quantum coherence—the remarkable phenomenon where electrons operate in synchronized harmony, akin to overlapping waves—has traditionally been confined to rare states such as superconductivity. In these exotic phases, electrons pair up to move through materials without resistance, creating the hallmark zero-resistance flow that has fascinated physicists for decades. Typically, in everyday metals, electrons collide and scatter frequently, destroying this delicate coherence almost instantly. However, groundbreaking research led by a team at the Max Planck Institute has turned this conventional wisdom on its head by demonstrating robust many-body quantum coherence in the Kagome metal CsV₃Sb₅—even in the absence of superconductivity.
This discovery centers on the unique geometrical structure of the Kagome lattice, a two-dimensional framework composed of corner-sharing triangles interwoven with hexagons, which creates a playground for electrons with frustrated magnetic interactions and unusual electronic characteristics. By carefully sculpting microscopic pillars of the Kagome crystal mere micrometers in size and subjecting them to magnetic fields, the researchers at the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) observed resistance oscillations reminiscent of the quantum mechanical Aharonov–Bohm effect. These oscillations provide compelling evidence that the electrons inside these pillars are not acting as independent particles but are instead engaging in collective interference indicative of many-body coherence extending well beyond the limitations predicted by traditional single-particle quantum mechanics.
One of the most astonishing aspects of this coherence was its strong sensitivity to the geometric shape of the crystal pillars. When the team fashioned the samples into rectangles, the resistance oscillation patterns shifted at right angles, yet when the shape was altered to a parallelogram, those shifts occurred precisely at 60° and 120°. This intimate linkage between crystal geometry and electron coherence suggests an unprecedented quantum state where the collective behavior of electrons “senses” the spatial configuration of their environment. It’s as if these electrons were performing a symphony, and the room’s architecture dictated the melody they played.
Philip Moll, the director overseeing this research, eloquently captured the essence of this phenomenon: “It’s as if the electrons know whether they’re in a rectangle or a parallelogram. They’re singing in harmony—and the song changes with the room they’re in.” This metaphor resonates deeply with the concept of shape-sensitive quantum states—a paradigm shift that introduces geometry as a fundamental knob controlling emergent quantum behavior in crystalline materials.
Historically, quantum coherence in metals has been an elusive and delicate feature, often annihilated by scattering events and thermal fluctuations. The Kagome lattice’s inherent geometric frustration provides an unusual environment where electrons are partially constrained and coupled in ways that promote exotic collective phenomena such as charge density waves and unconventional superconductivity. Yet in this study, the team uncovered coherence phenomena distinct from superconductivity, suggesting a new kind of quantum state whose coherence is maintained by many-body interactions rather than electron pairing.
What this means for the future of quantum materials and devices is profound. If electrons can maintain collective coherence over micrometer scales simply by virtue of the material’s geometric configuration, material scientists can harness these effects for novel applications. Instead of relying solely on chemical composition and atomic-scale structure, researchers might “tune” the quantum states by carefully sculpting the architecture of materials—turning geometry into a new frontier for quantum engineering.
Drawing an analogy to music, this discovery implies that Kagome metals behave not just as musical instruments with fixed tuning determined by their atoms, but as orchestras capable of changing their entire sound based on the concert hall they occupy. The electronic “song” arising from the Kagome lattice is thus a collective resonance that depends not only on atomic arrangement but also on the macroscopic shape of the crystal. This introduces an unprecedented level of control over electronic phases and quantum coherence, potentially enabling bespoke quantum functionalities tailored through architectural design.
The Hamburg team’s findings push the envelope of quantum coherence research far beyond the atomic scale—extending it to the mesoscale, where focused ion beam techniques can precisely carve crystals into desired shapes. Though currently confined to laboratory conditions, these shape-dependent quantum coherence effects herald the dawn of “geometry-governed” quantum materials. Such materials could form the basis for future electronic devices where geometry—not just chemistry or doping—dictates behavior, opening avenues to new technology paradigms in quantum computing, sensing, and beyond.
Chunyu Guo, the lead author of the study, emphasized the paradigm shift enabled by this work: “This is not what non-interacting electrons should be able to do. It points to a coherent many-body state.” The results thus hint at unexplored many-body physics that challenges present theoretical frameworks and demands new models that incorporate the interplay of geometry, quantum interference, and electron correlations.
Delving deeper into the quantum mechanics involved, the observed Aharonov–Bohm-like oscillations indicate that electrons traverse closed paths around the nanostructures, acquiring phase shifts dependent on the external magnetic field and the topology of these paths. Ordinarily, such interference effects decay rapidly in metals due to electron scattering, but the Kagome structure’s topology and symmetry protect and enhance these quantum states, enabling coherent electron wavefunctions to persist over unexpectedly long distances.
The potential technological implications extend past basic physics; engineers could leverage shape-engineered coherence for devices that are robust against decoherence and tailor-made for specific quantum functionalities. Quantum computers and electronic components of the future may benefit from being designed with “quantum architecture” considerations, where the macroscopic shape factors into device performance.
Moreover, the discovery rejuvenates longstanding scientific interest in Kagome lattices, which have been extensively studied for their topological and electronic properties. The interplay between geometry and electron behavior demonstrated here offers a new dimension for exploring quantum materials, challenging condensed matter physicists to rethink how material shape and dimensionality influence emergent phases.
While experimental challenges remain—especially in scaling these effects beyond the microscale and ensuring stability under practical operating conditions—the conceptual breakthrough achieved by the MPSD team lays the groundwork for revolutionary advances in quantum material design. The ability to “sculpt” coherence itself may redefine what is achievable in material science, quantum electronics, and beyond, heralding a future where quantum functionality is engineered and controlled through form as much as chemistry.
In summary, the quest to harness electron coherence without the crutch of superconductivity has taken a leap forward through the discovery of shape-sensitive many-body interference states in Kagome crystals. This study reveals a heretofore unknown quantum realm where electrons collectively “know” the contours of their environment, exhibiting robust coherence guided by the symmetries and shape of their host crystal. As material scientists begin to explore this dimension of quantum control, the age-old boundaries between chemistry, physics, and architecture will dissolve, giving rise to a new era of architected quantum materials.
Subject of Research: Not applicable
Article Title: Many-body interference in kagome crystals
News Publication Date: 29-Oct-2025
Web References: https://doi.org/10.1038/s41586-025-09659-8
Image Credits: © Guo et al.
Keywords
Quantum Coherence, Many-Body Interference, Kagome Lattice, CsV₃Sb₅, Aharonov–Bohm Oscillations, Geometric Quantum States, Electron Correlations, Quantum Materials, Shape-Dependent Quantum Phenomena, Topological Metals, Mesoscale Quantum Effects, Quantum Device Engineering
