Manipulating quantum material by engineering non-classical states of light

Interactions (or forces) between particles are mediated by the so-called force carriers, like photons mediating electromagnetic interactions between charges. New theoretical research predicts that when force carriers are prepared in a non-classical state (i.e. a configuration which is not allowed by classical mechanics), the two particles interact in a fundamentally new way.

Published in the scientific journal PRX Quantum, Louisiana State University physicist Dr. Ahana Chakraborty with her collaborators led the development of a novel nonequilibrium field-theoretical approach for computing the vertex function and find that, in addition to the energy and momentum structure of the scattering, a further structure emerges, which reflects the Hilbert-space distribution of the mediator’s quantum state. This emergent structure becomes nontrivial for non-Gaussian quantum states of the mediator and can dramatically affect two-body scattering.

This breakthrough research opens new avenues for controlling properties of quantum materials, especially collective phenomena by engineering the quantum state of the force carriers.

“As a first application, we show that by preparing cavity photons in pure Fock states one can enhance pair correlations, and even modify the criticality of the photon-mediated superconducting phase transition,” said Dr. Chakraborty.

In the publication ‘Controlling Collective Phenomena via the Quantum State of Interaction Mediators: Changing the Criticality of Photon-Mediated Superconductivity via Fock States of Light’, the lead author Dr. Chakraborty, in collaboration with other researchers, show that the quantum nature of the interaction-mediating photons can significantly alter two-body scattering and even shift the critical behavior of superconducting phase transitions.

As future research emerges, the authors note that the possibility for experimental investigation also exists at a less fundamental level, where the role of photons can be played by collective degrees of freedom like phonons, or by excitons (polaritons). While quantum-state-engineering is currently more developed for photons than for the rest of the candidate mediators like phonons, new promising platforms are emerging.

 Click the link to read the publication: https://journals.aps.org/prxquantum/abstract/10.1103/PRXQuantum.6.020341