Queens College, CUNY — Department of Physics

The talk explores a quantitative connection between Huygens’s legacies in wave optics and classical mechanics. Optical polarization, coherence and entanglement are related to mechanical quantities including centre of mass and moment of inertia. Distributions of classical point masses provide a representation of nonseparability in optical fields, and the correspondence extends to quantum states of two qubits. These mappings offer an intuitive way to examine entanglement and the shared mathematical structure of mechanics, classical optics and quantum physics.

Intermediate-band solar cells seek to absorb photons below the host band gap and increase current without sacrificing voltage. This talk examines submonolayer CdTe quantum dots embedded in ZnCdSe matched to InP, avoiding a harmful wetting layer and permitting hundreds of absorbing layers. Recent growth results show deeper photoluminescence associated with larger dots and improved intermediate-band placement. A complementary inverse-design study optimizes ZnCdSe/ZnCdMgSe distributed Bragg reflectors to recycle photons over 1–1.8 micrometres and incidence angles of 0–70 degrees. Total absorption guides optimization, with designs showing broad reflectivity and tolerance to fabrication errors.

This talk develops a first-principles description of interacting electrons, nuclei and electromagnetic fields by extending density-functional theory to quantum electrodynamics. It introduces electron–photon exchange-correlation functionals and photon many-body dispersion, a generalization of molecular dispersion methods that treats electronic and photonic degrees of freedom together. Applications examine anisotropic coupling, effects beyond single photons and cavity-modified van der Waals forces. The approach aims to retain these strong-coupling effects while remaining efficient enough to simulate large, complex systems inside optical cavities.