Optical excitation of electron spin coherence in NV centers is currently being explored for building solid-state optical devices for quantum information processing. This is possible due to the long coherence time of spin in the nitrogen vacancy (NV) color centers in diamond. Optical systems that can address isolated electron spins in individual color center and color center ensemble are significantly important for quantum information storage, entanglement generation, and single photon nonlinear interaction. We plan to develop instrument that will interface color centers in diamond nanocrystals with laser excitations to study quantum phenomena both at room and low (~70K) temperatures. Our instrument will provide single photon detection and measurement capabilities for doing quantum measurements. It will be used to explore coherence properties of nanocrystals for quantum information storage/retrieval, and single photon nonlinear interaction.