Light -- stopped or trapped inside a crystal? In the below experiment: http://www.extremetech.com/extreme/...-inside-a-crystal-the-basis-of-quantum-memory Opaque crystal of yttrium silicate doped with praseodymium 1. Is light stopped or trapped (i.e. internally reflecting, bouncing off the "walls")? 2. Will quantum coherence be preserved as long as the photon stays inside the crystal? 3. Is light "slowed" in water because of absorption and re-emittance of the photon?