Quantum Imaging in the Continuous-Wave Regime Using Degenerate Optical Cavities

Abstract

Images carry a lot of information, contained in the local intensity of the millions of pixels composing the image. From a quantum point of view, they must be described by a quantum state that spans over as many transverse modes as pixels. Quantum imaging is therefore the archetype of highly multimode quantum optics. Over the last two decades, theoretical and experimental studies have shown that resonant optical cavities are one of the most efficient devices to generate nonclassical states of light, such as squeezed, correlated, or entangled states. However, these states are actually single-mode nonclassical states, because the optical cavity imposes the transverse variation of the field to be one of its eigenmodes, generally the TEM00 mode. In order to produce the multimode nonclassical fields that are needed in quantum imaging, one must use special kinds of cavities: the degenerate optical cavities, in which a great number of transverse modes are likely to simultaneously oscillate. In this chapter, we will give a brief account of the domain of multimode quantum imaging using degenerate optical cavities. We will begin by a study at the classical level of the imaging properties of such cavities, then give the main results of the various theoretical studies that have been conducted to show that these devices were indeed interesting for the generation of local squeezing and spatial quantum correlations and entanglement. We will finally describe some recent experiments aimed at showing these effects.