Des scientifiques ont découvert une nouvelle façon de coopérer des molécules à température ambiante.

Scientists have discovered a novel mechanism by which molecules can synchronize their behavior at room temperature, challenging established theories about optical coherence. The breakthrough, detailed in a study published in Nature Nanotechnology, reveals that luminescent molecules confined within plasmonic nanogaps, tiny spaces between gold nanoparticles, can exhibit collective behavior even when light rapidly escapes from the system. This discovery has implications for developing advanced sensors, molecular photonics, and quantum technologies that function efficiently at ambient temperatures. The experiment involved placing luminescent molecules inside nanoscale gaps measuring less than a billionth of a meter wide. These structures, known as plasmonic cavities, were exposed to a continuous laser, and the resulting light emissions were carefully monitored. Initially, the light originated solely from the illuminated region. However, as the laser intensity increased, the emitted light expanded outward, forming a glowing halo that extended far beyond the initial illumination. This observation suggested that molecules located at considerable distances began to interact in a coordinated manner. Dr. Rakesh Arul, lead author of the study and a research fellow at the Cavendish Laboratory, explained that the transition from independent to collective behavior occurred as the laser power was increased. “We observed the molecules switching from acting independently to behaving collectively,” he stated. “At low laser power, the emitted light came only from the illuminated spot. As the power increased, the emission spread into a glowing halo far outside the laser beam, revealing that molecules separated by large distances were beginning to act together.” The findings indicate that the synchronization arises not from photons bouncing within an optical cavity, as traditionally assumed, but through direct electromagnetic coupling between the molecules. This interaction occurs within the narrow plasmonic nanogaps, enabling the formation of a synchronized dipole state. Despite the rapid escape of photons, the molecules maintain internal coherence, functioning as a unified system. To further explore these dynamics, the researchers employed a combination of laser excitation, interferometry, and quantum optical theory. Collaborating with Dr. Piper Fowler-Wright and Prof. Jonathan Keeling at the University of St. Andrews, they analyzed the data using cutting-edge theoretical models. Their analysis revealed that the synchronization stemmed from the direct interaction of molecular dipoles, rather than from the repeated reflection of light within a cavity. Interferometric measurements confirmed that the molecules achieved spatial coherence across the entire sample. One intriguing aspect of the study was the observation of spiral-like phase patterns, referred to as vortices. These structures suggest that even in a synchronized system, complex and dynamic behaviors can emerge. The presence of vortices indicates that the system does not simply settle into a static configuration but continues to evolve in intricate ways. This research represents a significant step forward in understanding how molecular systems can achieve coherent behavior without relying on traditional optical cavities. The ability to create synchronized states at room temperature could pave the way for more practical applications in fields such as sensing, quantum computing, and nanophotonics. Future studies will likely focus on refining these effects and exploring their potential in real-world technological applications.