Physicists have shown that direct interactions between atoms can amplify superradiance, a synchronized light emission effect, by incorporating quantum entanglement into their models. The research, involving scientists from the University of Warsaw and Emory University, reveals new principles for designing quantum batteries, sensors, and communication devices. Published in Physical Review Letters, the study highlights how overlooking atom-atom forces has limited previous understandings.
Researchers from the Faculty of Physics at the University of Warsaw, the Centre for New Technologies at the University of Warsaw, and Emory University in Atlanta, USA, have investigated how atoms interact with light in shared optical modes within cavities. Their work, detailed in a 2025 Physical Review Letters paper titled 'Role of Matter Interactions in Superradiant Phenomena' by João Pedro Mendonça, Krzysztof Jachymski, and Yao Wang (DOI: 10.1103/z8gv-7yyk), expands on superradiance models. Superradiance occurs when multiple atoms emit light in perfect synchronization, producing brightness exceeding individual emissions.
Traditional models treat atoms as a single 'giant dipole' coupled via photons, but the team included short-range dipole-dipole forces between nearby atoms. 'Photons act as mediators that couple each emitter to all others inside the cavity,' explained Dr. João Pedro Mendonça, the first author who earned his PhD at the University of Warsaw and now works at its Centre for New Technologies. These direct interactions can either compete with or reinforce photon-mediated coupling, influencing superradiance thresholds.
Quantum entanglement, the deep connection between particles, plays a central role. Many semiclassical approaches ignore it, treating light and matter separately. 'Semiclassical models greatly simplify the quantum problem but at the cost of losing crucial information; they effectively ignore possible entanglement between photons and atoms, and we found that in some cases this is not a good approximation,' the authors noted. The researchers developed a computational method to explicitly track entanglement and correlations, uncovering a new ordered phase with superradiance properties.
The findings have implications for quantum technologies. In cavity-based systems, superradiance could accelerate charging in quantum batteries, improving energy transfer efficiency. 'Once you keep light-matter entanglement in the model, you can predict when a device will charge quickly and when it won't. That turns a many-body effect into a practical design rule,' said Mendonça. Similar advances may benefit quantum communication networks and high-precision sensors. The collaboration, supported by programs like the University of Warsaw's 'Excellence Initiative -- Research University' (IDUB) and the Polish National Agency for Academic Exchange (NAWA), underscores the value of international mobility.