Rare Earth-Doped Crystals for Quantum Information Processing

Graphical Abstract Download full-size image Quantum information processing (QIP) uses superposition states of photons or atoms to process, store, and transmit data in ways impossible to reach with classical systems. Rare earth-doped crystals have recently emerged as promising systems for these applications, mainly because they exhibit very narrow optical transitions at low temperature. This allows to use these materials as quantum light-matter interfaces or to optically control their quantum states. In this chapter, after a brief introduction to QIP and coherent light-matter interactions, specific spectroscopic properties of rare earth-doped crystals are reviewed. This includes hyperfine structures, coherent properties of optical and hyperfine transitions, as well as techniques to extend coherence lifetimes. Two applications are then discussed in more details: quantum memories and computers. In these last parts, concepts and protocols are presented as well as a few representative experimental examples.