Search for: All records

The generation of exciton–polaritons through strong light–matter interactions represents an emerging platform for exploring quantum phenomena. A significant challenge in colloidal nanocrystal-based polaritonic systems is the ability to operate at room temperature with high fidelity. Here, we demonstrate the generation of room-temperature exciton–polaritons through the coupling of CdSe nanoplatelets (NPLs) with a Fabry–Pérot optical cavity, leading to a Rabi splitting of 74.6 meV. Quantum–classical calculations accurately predict the complex dynamics between the many dark state excitons and the optically allowed polariton states, including the experimentally observed lower polariton photoluminescence emission, and the concentration of photoluminescence intensities at higher in-plane momenta as the cavity becomes more negatively detuned. The Rabi splitting measured at 5 K is similar to that at 300 K, validating the feasibility of the temperature-independent operation of this polaritonic system. Overall, these results show that CdSe NPLs are an excellent material to facilitate the development of room-temperature quantum technologies. 

Coupling molecules to a quantized radiation field inside an optical cavity has shown great promise in modifying chemical reactivity. It was recently proposed that strong light-matter interactions are able to differentiate endo/exo products of a Diels-Alder reaction at the transition state. Using the recently developed parameterized quantum electrodynamic \textit{ab initio} polariton chemistry approach along with time-dependent density functional theory, we theoretically confirm that the ground state selectivity of a Diels-Alder reaction can be fundamentally changed by strongly coupling to the cavity, generating preferential endo or exo isomers which are formed with equal probability for the same reaction outside the cavity. This provides an important and necessary benchmark with the high-level self-consistent QED coupled cluster approach. In addition, by computing the ground state difference density, we show that the cavity induces a redistribution of electron density from intramolecular $$\pi$$-bonding orbitals to intermolecular bonding orbitals, thus providing chemically relavent description of the cavity-induced changes to the ground state chemistry and thus changes to the molecular orbital theory inside the cavity. We extend this exploration to an arbitrary cavity polarization vector which leads to critical polarization angles that maximize the endo=/exo selectivity of the reaction. Finally, we decompose the energy contributions from the Hamiltonian and provide discussion relating to the dominent dipole self-energy effects on the ground state. 

We derive the $$\mathcal{L}$$-MFE method to incorporate Lindblad jump operator dynamics into the mean-field Ehrenfest (MFE) approach. We map the density matrix evolution of Lindblad dynamics onto pure state coefficients using trajectory averages. We use simple assumptions to construct the $$\mathcal{L}$$-MFE method that satisfies this exact mapping. This establishes a method that uses independent trajectories which exactly reproduces Lindblad decay dynamics using a wavefunction description, with deterministic changes of the magnitudes of the quantum expansion coefficients, while only adding on a stochastic phase. We further demonstrate that when including nuclei in the Ehrenfest dynamics, the $$\mathcal{L}$$-MFE method gives semi-quantitatively accurate results, with the accuracy limited by the accuracy of the approximations present in the semiclassical MFE approach. This work provides a general framework to incorporate Lindblad dynamics into semiclassical or mixed quantum-classical simulations. 

This work provides the fundamental theoretical framework for few-mode cavity quantum electrodynamics by resolving the gauge ambiguities between the Coulomb gauge and the dipole gauge Hamiltonians under the photonic mode truncation. We first propose a general framework to resolve ambiguities for an arbitrary truncation in a given gauge. Then, we specifically consider the case of mode truncation, deriving gauge invariant expressions for both the Coulomb and dipole gauge Hamiltonians that naturally reduce to the commonly used single-mode Hamiltonians when considering a single-mode truncation. We finally provide the analytical and numerical results of both atomic and molecular model systems coupled to the cavity to demonstrate the validity of our theory.