A group of physicists from the Faculty of Physics and the Center for New Technologies at the University of Warsaw, along with researchers from Emory University in Atlanta, U.S., studied how interactions between atoms influence their collective behavior when interacting with light.
Enhancing Superradiance Through Atom Interactions
In a study published in Physical Review Letters, the researchers build upon existing models of the phenomenon. They demonstrate that direct interactions between atoms can enhance a collective emission of light called superradiance, highlighting new possibilities for advancing quantum technologies.
Light–matter systems involve placing multiple emitters, such as atoms, within a shared optical mode of a cavity—a specific light pattern confined between closely spaced mirrors. This setup allows for collective behaviors that do not occur with individual, isolated atoms.
A key example of this is superradiance—a quantum collective effect in which numerous atoms emit light in sync, resulting in radiation far more intense than what each atom would produce on its own.
Beyond the Giant Dipole Model
Typically, research on this effect assumes that the interaction between light and matter is the dominant factor. Under this assumption, the entire group of atoms is treated as a single “giant dipole” that couples uniformly to the cavity’s electromagnetic field, allowing for interactions that extend across the entire system.
“Photons serve as connectors, linking each emitter to all the others within the cavity,” explains Dr. João Pedro Mendonça, the lead author of the study, who earned his Ph.D. at the Faculty of Physics, University of Warsaw, and is currently a researcher at the Center for New Technologies at the same university.
In actual materials, however, nearby emitters also affect one another through short-range dipole–dipole interactions—effects that are often overlooked. This research explores how the situation changes when these inherent atom–atom interactions are taken into account.
Balancing Interactions and Preserving Entanglement in Superradiance
The study reveals that these atom–atom interactions can either oppose or enhance the photon-mediated interactions responsible for superradiance. Grasping this interplay is crucial for accurately interpreting experiments where light and matter strongly influence one another.
At the heart of the combined light–matter behavior is entanglement. However, many analytical and computational models treat light and matter as separate systems, which effectively erases this vital connection.
“Semiclassical models simplify the complex quantum dynamics, but they do so by sacrificing key details,” the authors note. “In particular, they ignore potential entanglement between photons and atoms—and in certain situations, we found this simplification to be inadequate.”
Computational Insights into Entangled Superradiance
The researchers present a computational method that explicitly retains entanglement, allowing them to accurately capture correlations both within individual subsystems and between them.
Applying this approach, they demonstrate that natural interactions between nearby emitters can reduce the threshold for superradiance and uncover a previously unrecognized ordered phase exhibiting superradiant characteristics. Overall, the findings highlight that including entanglement is crucial for fully mapping the range of possible states in light–matter systems.
Beyond its theoretical importance, this work has practical implications for emerging quantum technologies. One notable application is quantum batteries—devices that could, in theory, achieve faster and more efficient charging and discharging by leveraging collective quantum effects.
Tuning Superradiance for Efficient Energy Transfer
Superradiant behavior can speed up both the charging and discharging processes, enhancing energy transfer efficiency. This study sheds light on how short-range interactions between nearby emitters influence those dynamics: by altering the conditions for superradiance and guiding the system between different states, these inherent interactions become adjustable design parameters for optimizing charging performance in real-world materials and optical cavities.
“When you include light–matter entanglement in the model, you gain the ability to predict whether a device will charge efficiently or not. That transforms a complex many-body effect into a practical design principle,” said João Pedro Mendonça. Gaining similar control over light–matter correlations is also valuable for other technologies, such as quantum networks and high-precision sensors.
The project emerged from an international collaboration that brought together expertise from several institutions. João Pedro Mendonça conducted multiple research visits to the U.S., and close international cooperation was central to the success of the study. “This is a great example of how international mobility and collaboration can lead to important breakthroughs,” the team emphasized.
Read the original article: Phys.Org
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