Quantum Diamond Shines On

Diamond is already a popular host material for quantum bits. Two groups have now demonstrated new ways to use diamond to build other essential elements in a quantum architecture: quantum memories and quantum repeaters. Benjamin Sussman and co-workers at the National Research Council of Canada and the Institute for Quantum Computing in Waterloo, Canada, have shown that single photons can be stored in, and retrieved from, vibrations in a diamond lattice—realizing a memory that works at room temperature and higher speed than existing schemes. And Hideo Kosaka and Naeko Niikura at the Yokohama National University, Japan, have shown that a photon can be entangled with the internal spin state of a nitrogen-vacancy defect in diamond. Their scheme could serve as a quantum repeater, a device that faithfully transfers entanglement between an incoming and an outgoing photon.