As premier information carriers in optical sciences and quantum physics, photons exhibit remarkable coherence and move at the absolute speed limit, serving as the foundation for quantum-enhanced optical systems and high-speed communications.
Yet, these advantages are coupled with a fundamental physical limitation — the absence of direct photon-photon interactions.
The Quantum Insider reported that to bypass this obstacle, scientists belonging to Saint Louis University alongside a pair of German research centers applied numerical simulations, revealing that classical nonlinear light dynamics can stimulate effective photon interactions and cause quantum light to thermalize.
Researchers representing the Max Born Institute, Humboldt-Universität zu Berlin, and Saint Louis University’s School of Science and Engineering published findings in Science Advances showing that multimode nonlinear optical platforms can be utilized to provoke functional quantum interactions among photons, leading to their subsequent thermalization. The investigators explored configurations where quantum light travels alongside significantly robust classical light fields inside multimode nonlinear optical architectures.
Single- and two-photon states embedded in these configurations did not merely maintain their initial states or suffer unmitigated decoherence; instead, they thermalized. The appearance of distinct statistical distributions, aligning precisely with Boltzmann and Rayleigh-Jeans distributions, validates this thermalization process.
“By leveraging the intense classical wave dynamics to mediate effective interactions, the system successfully bridges the gap between macroscopic nonlinear optics and microscopic quantum mechanics,” Armando Perez-Leija told The Quantum Insider.
Perez-Leija is a research scientist at Saint Louis University.
This strategy may supply a viable setup to investigate open quantum systems and quantum thermodynamics minus the necessity for materials featuring powerful single-photon nonlinearities. Instead of relying on rare, exceptionally strong single-photon nonlinear materials — which are notoriously difficult to fabricate and scale — the method achieves effective quantum thermalization using standard, readily available classical optical structures.
“The implications of this work extend far beyond foundational optics, reaching deep into statistical mechanics and condensed matter physics,” said El-Ganainy.
El-Ganainy is a professor of electrical and computer engineering at Saint Louis University, alongside Şahin K. Özdemir, who is a professor and chair of electrical and computer engineering at the institution.
Additional contributors to the research paper comprise Fouad Chahrour affiliated with the Max Born Institute and Humboldt University of Berlin, alongside Kurt Busch, who serves as a professor of theoretical physics at the Max Born Institute and the Institute of Physics in the Humboldt University of Berlin.
“By establishing that classical nonlinearities can effectively thermalize quantum states, the framework offers researchers a powerful, highly controllable testbed for investigating open quantum systems and many-body thermodynamics,” El-Ganainy told The Quantum Insider.
This platform allows researchers to explore a wider spectrum of complex quantum phenomena, including quantum phase transitions, within standard laboratory optical settings.
“By lowering the experimental barriers required to study complex quantum photon interactions, the research opens fresh avenues for light dynamics and deepens our fundamental understanding of how statistical equilibrium emerges in quantum systems,” Özdemir told The Quantum Insider.
This research was supported by the US Air Force Office of Scientific Research and the Army Research Office.
Earlier coverage: Researchers Use Classical Light to Induce Quantum Thermalization in Photons
