In an unprecedented leap forward in condensed matter physics, an international team of researchers led by Pengcheng Dai at Rice University has unequivocally confirmed the presence of emergent photons and fractionalized spin excitations within a rare and elusive quantum spin liquid. This landmark discovery, recently published in Nature Physics, identifies the crystalline compound cerium zirconium oxide (Ce₂Zr₂O₇) as a definitive three-dimensional realization of this exotic quantum state. The implications of this breakthrough extend far beyond fundamental physics, holding promise for revolutionary applications in quantum computing and lossless energy transmission technologies.
Quantum spin liquids have long mystified physicists due to their enigmatic magnetic properties and strong quantum entanglement. Unlike conventional magnetic materials that exhibit ordered spin alignment below certain temperatures, quantum spin liquids defy this norm by maintaining a fluctuating, entangled state down to near absolute zero. This persistent fluidity of magnetic moments engenders emergent quasiparticles and novel excitations—most notably emergent photons and spinons—that behave fundamentally differently from ordinary magnetic excitations.
The significance of confirming emergent photons within Ce₂Zr₂O₇ cannot be overstated. Emergent photons arise as collective excitations within the spin system, effectively mimicking the behavior of photons in electromagnetic fields but borne out of the underlying quantum entanglement of spins. Their existence had been predicted theoretically for decades in the context of quantum spin ice—a subclass of quantum spin liquids exhibiting ‘magnetic monopole’ excitations—but definitive experimental evidence had remained elusive until now.
Key to this breakthrough was the utilization of state-of-the-art polarized neutron scattering techniques, which allowed the researchers to meticulously isolate magnetic scattering signals from background noise and other scattering events. These measurements, conducted at multiple international laboratories equipped with cutting-edge neutron instrumentation, enabled the team to detect emergent photon signals at near-zero energy—a hallmark fingerprint unique to quantum spin ice states. The extraordinary sensitivity of polarized neutrons to magnetic fluctuations provided the crucial clarity required to observe such subtle phenomena.
Complementing the neutron scattering data, precise thermodynamic measurements, including specific heat analysis, fortified the claim of emergent photons. The specific heat profile indicated an excitation spectrum with dispersion characteristics analogous to phonons—the quantized sound waves in solids—yet distinctly attributable to the spin degrees of freedom. This interplay between neutron scattering and thermodynamics paints a coherent picture of Ce₂Zr₂O₇ hosting a dynamic, highly quantum-entangled spin lattice.
The path to this discovery was strewn with formidable experimental challenges. Quantum spin liquids operate in the extreme quantum regime at temperatures approaching absolute zero, where thermal fluctuations are suppressed, but signals become faint and noise becomes dominant. Earlier attempts were often thwarted by technical noise and incomplete data, clouding interpretations. However, the Rice-led team overcame these hurdles by attaining refined single-crystal sample quality and deploying unprecedented instrumental precision, benefiting from an international collaboration that brought together expertise from major facilities in Europe and North America.
Crucially, this discovery of emergent photons and spinons extends the known realm of quantum spin liquids into unambiguously three-dimensional materials. Previous experiments had struggled to isolate such phenomena unequivocally in bulk 3D compounds, often limited to two-dimensional or quasi-2D systems with more straightforward magnetic behavior. Ce₂Zr₂O₇, with its geometrically frustrated pyrochlore lattice, offers a robust platform for exploring the emergent quantum electrodynamics encoded within its spin dynamics.
The theoretical import of this finding is profound, confirming a key prediction of quantum spin ice theory and validating decades of sophisticated modeling. According to Bin Gao, the study’s first author and physicist at Rice, this result propels the field forward by demonstrating tangible evidence that long-hypothesized emergent quasiparticles indeed inhabit real materials. It invites scientists to deepen their exploration into similar exotic states, potentially revolutionizing our comprehension of magnetism under conditions governed by strong quantum correlations.
Beyond the realm of pure physics, the implications for technology are enticing. Quantum spin liquids, with their non-traditional spin states and fractionalized excitations, are prime candidates for quantum information processing, where robustness against decoherence is paramount. Moreover, the discovery of dissipationless excitations emulating photons inside solid-state systems could pave new avenues toward ultra-efficient signal transmission, with minimal energy loss.
This collaborative effort united a constellation of experts, including Félix Desrochers and Yong Baek Kim from the University of Toronto, Rice alumnus David Tam from the Paul Scherrer Institut, and Silke Paschen’s group at the Vienna University of Technology, alongside contributors from the Institut Laue-Langevin, the Jülich Centre’s Heinz Maier-Leibnitz Zentrum, and Rutgers University. Their pooled resources and expertise underscored the global importance and multi-institutional nature of advancing experimental quantum materials research.
Funding from the U.S. Department of Energy, the Gordon and Betty Moore Foundation, and the Robert A. Welch Foundation was instrumental in enabling this research, underpinning the necessary experimental infrastructure and personnel support. The synergy between financial investment and scientific ingenuity facilitated navigating the complexities of both material growth and advanced neutron scattering measurements.
Professor Dai articulates the broader context succinctly: “By conclusively confirming emergent photons and spinons in Ce₂Zr₂O₇, we provide the scientific community not only with answers to a historic puzzle but also with a fertile ground for innovation. The study pushes the frontier of quantum matter, revealing an unprecedented playground where new quantum states manifest, reshaping our grasp of fundamental physics and technological horizons.”
In synthesis, this groundbreaking study marks a milestone in the quest to unravel strongly correlated quantum states. The clear identification of a quantum spin liquid with emergent electrodynamics in a three-dimensional crystalline material signals a new era in condensed matter physics, encouraging intensified investigation into quantum materials that challenge classical intuition and offer pathways towards next-generation quantum devices.
Subject of Research: Quantum Spin Liquids; Emergent Photons; Fractionalized Spin Excitations; Ce₂Zr₂O₇ Quantum Spin Ice
Article Title: An international team of scientists led by Rice University’s Pengcheng Dai has confirmed the existence of emergent photons and fractionalized spin excitations in a rare quantum spin liquid. Published in Nature Physics on June 19, their findings identify the crystalline compound cerium zirconium oxide (Ce₂Zr₂O₇) as a clear, 3D realization of this exotic state of matter.
News Publication Date: 19-Jun-2025
Web References:
https://www.nature.com/articles/s41567-025-02922-9
http://dx.doi.org/10.1038/s41567-025-02922-9
References:
Dai, P., Gao, B., Desrochers, F., Kim, Y.B., Tam, D., Paschen, S., Kirschbaum, D., Nguyen, D.H., Steffens, P., Hiess, A., Su, Y., Cheong, S-W. (2025). Observation of emergent photons and spinons in a three-dimensional quantum spin liquid. Nature Physics. DOI: 10.1038/s41567-025-02922-9
Image Credits: Photo by Jeff Fitlow/Rice University
Keywords
Photon reactions; Spin polarization; Quantum computing; Neutrons; Electromagnetism; Magnets; Absolute zero
