Playing with light and molecules: a versatile platform for exploring exotic quantum matter
In a Physical Review Letters publication, ICFO researchers have theoretically proposed a new method that uses molecules and light to study exotic states of matter in which several quantum effects, such as non-local interactions and geometric frustration, can emerge. The platform is more versatile and robust than existing alternatives.
Quantum effects can be elusive, intricate, and deeply complex. That’s why, sometimes, researchers need to specifically design platforms that imitate these quantum phenomena in a “clean” and highly controllable manner, minimizing the disturbances often found in nature. Sometimes, as it turns out, these synthetic quantum matter systems are their only means to grasp such effects.
Traditionally, researchers have used ultracold atoms to engineer complex quantum interactions, including non-local couplings –interactions that span the entire system, allowing distant atoms to influence each other. Non-local couplings lie at the core of fundamental quantum properties like entanglement, and can give rise to phenomena of interest, such as geometrical frustration, in which these interactions prevent the system from settling into a unique configuration that minimizes its energy, potentially leading to exotic phases of matter.
These platforms, while effective, often require rapid, repetitive manipulations to induce this kind of quantum phenomena, which can introduce unwanted heating, decoherence, or other negative side effects. In the quest for a versatile and more robust platform, ICFO researchers Pavel P. Popov and Dr. Joana Fraxanet, led by ICREA Prof. Maciej Lewenstein, and in collaboration with ICFO Alumnus Dr. Luca Barbiero from the Politecnico di Torino, have presented a new approach in Physical Review Letters that overcomes such limitations.
Their proposal requires only two main ingredients: a cloud of molecules and light. “By scattering a laser beam off these molecules, we can create a controllable environment for photons that mimics the behavior of electrons in a solid material,” explains Pavel Popov, first author of the article. The molecules in the cloud, however, must be distributed in a particular way. The researchers can then tune how the scattered photons propagate and interact by carefully controlling and modifying this spatial distribution. “This setup is able to simulate systems that are notoriously hard to simulate numerically in a very versatile manner,” adds the researcher.
Indeed, the team theoretically proved that, with the appropriate adjustments, exotic physical phenomena can emerge, including non-local couplings, geometrical frustration, and even artificial magnetic-like fields, which affect light’s motion similar to how real magnetic fields affect electrons. If experimentally realized, their model could become an ideal playground for exploring chiral superfluids, exotic phase transitions, topological phases of matter, and other yet-undiscovered quantum phases. According to Prof. Maciej Lewenstein, lead researcher of the study: “Understanding the physics this kind of systems host can advance technological progress that could, for example, help us building superconductors at room temperature.”
Reference:
Pavel P. Popov and Joana Fraxanet and Luca Barbiero and Maciej Lewenstein, Geometrical frustration, power law tunneling and nonlocal gauge fields from scattered light, Phys. Rev. Lett. 136, 103403 (2026).
DOI: https://doi.org/10.1103/hndj-8tj1
Acknowledgements:
ICFO-QOT group acknowledges support from: European Research Council AdG NOQIA; MCIN/AEI (PGC2018-0910.13039/501100011033, CEX2019-000910-S/10.13039/501100011033, Plan National FIDEUA PID2019-106901GB-I00, Plan National STAMEENA PID2022-139099NB, I00, project funded by MCIN/AEI/10.13039/501100011033 and by the “European Union NextGenerationEU/PRTR” (PRTR-C17.I1), FPI); QUANTERA MAQS PCI2019-111828-2; QUANTERA DYNAMITE PCI2022-132919, QuantERA II Programme co-funded by European Union’s Horizon 2020 program under Grant Agreement No 101017733; Ministry for Digital Transformation and of Civil Service of the Spanish Government through the QUANTUM ENIA project call - Quantum Spain project, and by the European Union through the Recovery, Transformation and Resilience Plan – NextGenerationEU within the framework of the Digital Spain 2026 Agenda; Fundació Cellex; Fundació Mir-Puig; Generalitat de Catalunya (European Social Fund FEDER and CERCA program, AGAUR Grant No. 2021 SGR 01452, Quantum-CAT U16-011424, co-funded by ERDF Operational Program of Catalonia 2014-2020); Barcelona Supercomputing Center MareNostrum (FI-2023-3-0024); Funded by the European Union. (HORIZON-CL4-2022-QUANTUM-02-SGA PASQuanS2.1, 101113690, EU Horizon 2020 FET-OPEN OPTOlogic, Grant No 899794, QU-ATTO, 101168628), EU Horizon Europe Program (This project has received funding from the European Union’s Horizon Europe research and innovation program under grant agreement No 101080086 NeQSTGrant Agreement 101080086 — NeQST); ICFO Internal “QuantumGaudi” project; European Union’s Horizon 2020 program under the Marie Sklodowska-Curie grant agreement No 847648; P.P.P. acknowledges also support from the “Secretaria d’Universitats i Recerca del Departament de Recerca i Universitats de la Generalitat de Catalunya” under grant 2024 FI-3 00390, as well as the European Social Fund Plus. L. B. acknowledges financial support within the DiQut Grant No. 2022523NA7 funded by European Union– Next Generation EU, PRIN 2022 program (D.D. 104- 02/02/2022 Ministero dell’Università e della Ricerca).