Theory and applications of entangled photons

Hisaki Oka, Hajime Ishihara

Nonlinear optical response of cavity polaritons formed in high-g semiconductor microcavities has attracted much attention because of their potential applications to entangled-photon sources and other quantum information technologies. Theoretical ideas of entangled-photon generation, e.g., biexcitonic cavity quantum electrodynamics and polariton-polariton scattering, have been suggested, however these theories are limited in scope of target because they restrict two-exciton states to either biexciton or unbound two-exciton states. As for exciton system with small binding energy of biexciton, it is likely that the interplay between the biexciton and unbound two-exciton states have much impact on generation efficiency of entangled photons. The authors introduces a general model including both biexciton and unbound two-exciton states and discuss generation efficiency of entangled photons.

Todd S. Larchuk

Hisaki Oka

Application of quantum entangled photons is now extending to various fields in physics, chemistry and biology. In particular, in terms of application to molecular science, broadband ultraviolet frequency-entangled photons are desired because molecules inducing photochemical reactions of interest often have electronic transition energies in the ultraviolet region. Recent standard method for generating such entangled photons is a chirped quasi-phase-matching method, however this method is not suitable for the generation of ultraviolet frequency-entangled photons because it requires down-conversion of a photon with a wavelength shorter than ultraviolet into an entangled photon pair. Here we propose a simple method for generating broadband ultraviolet frequency-entangled photons using cavity quantum plasmonics, in which conventional cavity quantum electrodynamics theory is applied to quantum plasmonics. We introduce a cavity-plasmon system in which localised surface plasmon (LSP) is coupled to the cavity fields of a state-of-the-art microcavity. Using this system, we theoretically show that broadband ultraviolet frequency-entangled photons can be generated simply by utilising the absorption saturation effect of LSP.

Zhen-Sheng Yuan, Xiao‐Hui Bao, Chao‐Yang Lu +3 more

Terence E. Stuart

Quantum theory provides a way to describe the behaviour of matter and energy on the nano-scale, but its predictions are sometimes very surprising. Intuition, based on experience from our daily lives, suggests there are a set of assumptions that should be applicable even when describing quantum systems. In this thesis we conduct a sequence of experiments that test some alternative theories to quantum theory and, in doing so, show that we must abandon some assumptions we made based on intuition if we are to accurately describe nature. In this thesis we also conduct an experiment that bounds the maximum predictive power that theories may have if they are to describe nature at the quantum level accurately. These experiments were conducted using a novel source of polarization entangled photon pairs, whose construction and characterization are also discussed.

Climério Paulo da Silva Neto