Welcome to my Science blog. These are comments on results that could be (or even are) published.
The Hilbert space is a big place. In the words of Douglas Adams (?!):
This year's European Research Night in Madrid (see ) was oriented to the very young public (at least this is how the Universidad Autónoma de Madrid understood it , and indeed a good fraction of the audience consisted of children).
Our group, that is generously funded by the EU, participated this year again to this event (see here for our last year input), this time with Elena, Carlos & Camilo impersonating herself, Schrödinger & Newton, respectively, to explain the "collapse of the quantum wavefunction" (see what Wikipedia says about that).
Explaining to young people a concept that is still not very well understood by the most experts in the field is a real challenge. This was brilliantly tackled with things that really collapse when probed hard enough: balloons.
Exciting something with light is such a basic notion, it does not even have a proper subject classification. You would call that "optical excitation", for instance, but it's not something for which you would find a page on Wikipedia. Depending on whom you ask, the closest match could turn out to be something quite different. I would intuitively think of "spectroscopy", which however by far neither fully includes nor is fully included in the original concept.
Photon correlations are a resource for quantum information processing. If only for the particular case of quantum cryptography: at the single photon level, they can be used for the BB84 protocol. At the two-photon level, they can power the Ekert version that relies on entanglement. It is one requisite if we are to develop a quantum technology to find, engineer and optimize photon correlations.
Take a light source. Any light source would do, but for convenience, let us consider a laser.