Vector beams - classical analogues to quantum entanglement

Classical light beams and even single photons are characterised by many different degrees of freedom, including their complex spatial shape, momentum, and polarisation. While conventional quantum entanglement describes correlations between different particles, classical systems can exhibit (non-classical) correlations between different degrees of freedom. This project will characterise the efficiency and fidelity of generating arbitrary complex vector beams, determine their correlations in multiple degrees of freedom and identify the classical analogues to quantum protocols.



First experiments have already demonstrated the analogue of a Bell inequality, usually linking the degrees of freedom of spin angular momentum and orbital angular momentum. We will extend this to include arbitrary complex spatial modes, polarisation and momentum (or path), building on the existing expertise of the Glasgow Optics group in this field. We will investigate the classical analogues to entanglement in higher dimension, including GHZ states and Werner states.



Particular attention will be given to the propagation of vectorial light fields through nonlinear media, and their interaction. Polarisation-dependent (nonlinear) spectroscopy is a striving research area at the interface between physics and the life sciences. We will explore the effects of structured polarisation for spectroscopy, sensing and communication. While we are not envisaging working with a strictly quantum system, our use of methodologies and concepts borrowed from quantum theory means that this project is closely aligned with the EPSRC quantum technology theme.