Imaging high-dimensional spatial entanglement with a camera

Abstract

The light produced by parametric down-conversion shows strong spatial entanglement that leads to violations of EPR criteria for separability. Historically, such studies have been performed by scanning a single-element, single-photon detector across a detection plane. Here we show that modern electron-multiplying charge-coupled device cameras can measure correlations in both position and momentum across a multi-pixel field of view. This capability allows us to observe entanglement of around 2,500 spatial states and demonstrate Einstein–Podolsky–Rosen type correlations by more than two orders of magnitude. More generally, our work shows that cameras can lead to important new capabilities in quantum optics and quantum information science.

Abstract

Measuring the entanglement between down-converted photons is central to many quantum optical experiments, and is normally performed by scanning detectors stepwise across a plane. Edgar et al. use a CCD camera to measure the entire entangled light field, finding strong correlations in position and momentum.