This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).
Spontaneous emission occurs when an atom gives up its excess energy by releasing a particle of light, or photon. However, if the atom is placed near a mirror, this process can be inhibited, allowing the atom to keep its energy. The question is, if the atom does not emit a photon, then how does it sense the presence of the mirror in the first place? Quantum theory predicts that, even when the atom's emission is "inhibited," there is still a probability to find a photon between the atom and the mirror. This prediction of quantum theory will be tested for the first time experimentally, by quickly removing the mirror and timing the arrival of photons at a nearby detector. The spontaneous emission will come not from a single atom, but from a parametric downconverter, another optical device that undergoes spontaneous emission. The experiment will provide the first direct evidence for photons emitted under these conditions.
More generally, the techniques developed for this experiment may improve the stability of quantum light sources, and allow the tailoring of their properties for special needs, such as transmission through optical fiber or other optical elements. These sources, in turn, may benefit society as elements of quantum computation or quantum cryptography systems. In addition, this work will provide undergraduate students with excellent training in research, giving them experience with lasers, modern optics, electronics, and calculational methods. Undergraduates working on this project will also confront foundational issues in quantum mechanics concerning the nature of light, and see a real-world example of quantum theory in action.
