Whereas classical electromagnetism predicts coherent phenomena in optics relating to the Einstein B coefficient (absorption and stimulated emission), Dicke (1954) also predicts that the Einstein A coefficient (spontaneous emission) is subject to modification due to coherence. Rare-earth impurity ions in a solid host are excellent systems to explore Dicke state effects. Because of the inhomogeneous bandwidth of the ionic levels, individual ions interact with a tunable density of atoms with nearly identical atomic levels. The observed homogeneous bandwidth of a given ion should depend on this density. The project will describe such phenomena in model systems (e.g., arrays of ideal two-level systems, a.k.a. qubits) as well as praseodymium-doped orthosilicate (Pr:YSO) under actual operating conditions. Our group operates a quantum memory experiment in Pr:YSO at the Joint Quantum Institute of the University of Maryland. Candidates with theoretical interest, or joint theoretical /experimental candidates are encouraged to apply.