Researchers at the University of East Anglia have established a novel approach to harness quantum light for observing quantum sound.
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In a newly published paper, the team has unveiled the intricate quantum interplay between molecular vibrations and particles of light, or photons. This breakthrough holds promise for enhancing our comprehension of the intricate interactions between light and matter at the molecular level.
Furthermore, it offers the potential to delve into essential inquiries about the significance of quantum effects across various domains, spanning from emerging quantum technologies to biological systems.
There is a long-standing controversy in chemical physics about the nature of processes where energy from particles of light is transferred within molecules. Are they fundamentally quantum-mechanical or classical? Molecules are complex and messy systems, constantly vibrating. How do these vibrations affect any quantum-mechanical processes in the molecule?
Dr. Magnus Borgh, School of Physics, University of East Anglia
“These processes are typically investigated using techniques that rely on polarisation – the same property of light used in sunglasses to reduce reflections. But this is a classical phenomenon. Techniques from quantum optics, the field of physics that studies the quantum nature of light and its interactions with matter on the atomic scale, can offer a way to investigate genuine quantum effects directly in molecular systems,” adds Dr. Magnus Borgh.
The study of correlations in the emitted light from a molecule placed in a laser field can help to reveal new aspects of quantum behavior. Correlations help to answer the question of how likely it is that two photons are emitted very close together and can be measured using standard techniques.
Our research shows that when a molecule exchanges phonons – quantum-mechanical particles of sound – with its environment, this produces a recognizable signal in the photon correlations.
Ben Humphries, PhD Student, Theoretical Chemistry, University of East Anglia
While laboratories worldwide regularly create and measure photons, the individual quanta of vibrations, known as phonons, associated with sound cannot typically be measured in the same way.
The recent discoveries offer a valuable set of tools for exploring the realm of quantum sound within molecules.
We have also computed correlations between photons and phonons. It would be very exciting if our paper could inspire the development of new experimental techniques to detect individual phonons directly.
Dr. Garth Jones, Lead Researcher, School of Chemistry, University of East Anglia
Humphries, B. S., et al. (2023). Phonon Signatures in Photon Correlations. Physical Review Letters. doi.org/10.1103/physrevlett.131.143601.