Quantum Light in Optical Cavities Enhances Superconductivity in MgB₂ using First Principles Quantum Electrodynamics (QEDFT)

Researchers at the Max Planck Institute for the Structure and Dynamics of Matter have made a groundbreaking advancement in light-controlled superconductivity, demonstrating that superconducting properties can be enhanced by coupling materials with quantum light in optical cavities. This study uses magnesium diboride (MgB₂), a well-known phonon-mediated superconductor, and employs state-of-the-art quantum electrodynamical density-functional theory (QEDFT) to reveal how photon vacuum fluctuations inside an optical cavity can increase its superconducting transition temperature.

The research shows that when MgB₂ is placed inside an optical cavity, the interaction with vacuum electromagnetic fields profoundly alters its electronic structure and phononic properties, particularly influencing the material’s superconducting critical temperature (T_c). The study found that, through careful selection of the cavity's polarization and mode setup, the superconducting T_c of MgB₂ could increase by up to 10%. This change is attributed to enhanced electron-phonon coupling and modified phonon frequencies induced by the cavity environment.

“Our findings are a crucial step toward creating new, light-controlled superconductors and offer a potential and unconventional path for engineering solid-state materials using photon vacuum fluctuations inside optical cavities,” explains Angel Rubio, Director at the Max Planck Institute and leader of the study.

The study explores a novel paradigm where materials' fundamental properties can be altered through their interaction with light at equilibrium, without requiring external energy or disrupting the system. This represents a shift from the traditional approaches of modifying material phases using external parameters like temperature or pressure. The team’s work not only advances the understanding of light-matter interactions but also sets the foundation for "cavity engineering materials," which could bring transformative applications in electronics, quantum technology, and beyond.

This research opens new doors for experimental exploration and could catalyze advancements toward cavity engineering solid-state materials. The lead author of the work, I-Te Lu, a postdoc working with Prof. Angel Rubio, believes that “continued work on cavity-engineered materials could yield new, tunable properties that are difficult to achieve through conventional methods, thereby pushing the frontiers of material science.”