Molecular Polaritons at the Quantum Frontier: From Cavity QED Foundations to Photonic Qubit Architectures

ABSTRACT

Molecular polaritons, hybrid quasiparticles formed through the strong coupling between molecular transitions and confined electromagnetic modes, have opened a new era by the combination of quantum electrodynamics (QED) with molecular photonics. This review deals with the theoretical, computational, and experimental developments that have put molecular polaritons at the forefront of next‐generation quantum information processing, photonics, and molecular‐scale qubit engineering. Starting from the Pauli–Fierz Hamiltonian, and other QED‐like macroscopic, ab initio, and QED‐coupled‐cluster methods which provide chemically accurate descriptions of correlated electron–photon states. A major focus is placed on dipole‐mediated quantum gates using rotational and polaritonic qubits, where long‐range dipole–dipole interactions enable scalable, room‐temperature logic operations. The article further discusses cutting‐edge spectroscopic methods such as 2D femtosecond stimulated Raman scattering, ultrafast pump‐probe, and cavity‐enhanced Raman reveals dark‐state dynamics, coherence transfer, and vacuum‐modified photo dynamics. Finally, we highlight recent advances in implementing polariton‐based logic gates, qubit analogs, and entanglement schemes that preserve coherence. Together, these advances establish molecular polaritons as chemically versatile and technologically promising candidates for on‐chip quantum logic and room‐temperature quantum photonic circuits, uniting the experimental realizations with quantum optical theory to chart a pathway for scalable, tunable, and coherent quantum information technologies.