Probing The Quantum Vacuum Using Nonlinear Crystals A Macroscopic Quantum Electrodynamics Perspective

Probing the Quantum Vacuum Using Nonlinear Crystals: a Macroscopic Quantum Electrodynamics Perspective

Abstract: Vacuum fluctuations of the electromagnetic field associated with the ground state exist as a consequence of Heisenberg's uncertainty principle. These fluctuating fields manifest themselves indirectly through their influence on matter where they may be regarded as responsible for important processes in nature, e.g. spontaneous emission, the Lamb shift, Casimir and Casimir-Polder forces. More recently, an alternative route to observing the quantum vacuum has been developed in electro-optic sampling experiments: they are based on the output statistics of ultrashort laser pulses sent through nonlinear crystals whose optical properties are influenced by the vacuum fluctuations. In this thesis, we develop a theoretical framework based on macroscopic quantum electro- dynamics for describing the propagation of quantised electric fields through a nonlinear crystal allowing for general environments. We apply this framework to the setup of electro-optic sampling, finding a description of the experiments which extends previous theoretical results beyond the paraxial approximation and by allowing for general ab- sorptive and dispersive environments via the classical Green's tensor. We show that the predictions of our theory for electro-optic sampling experiments in bulk media are in good agreement with the experimental data, recovering previous theoretical findings in certain limits, and how these experiments can be used to individually measure longitudinal or transverse fluctuating fields. We argue that by modifying the experimental setup, one can observe different characteristics of the environment-assisted quantum vacuum such as changes induced by metallic plates and cavities or surface resonances of these objects. This makes it possible to experimentally test the theoretical predictions for the medium-assisted ground state of quantum electrodynamics and thereby forging the missing link between geometry-induced vacuum effects such as e.g. the Casimir effect and electro-optic sampling of the vacuum

Journal of the Optical Society of America

Photonic Applications in Nonlinear Optics, Nanophotonics, and Microwave Photonics

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