Atom-like crystal defects: From quantum computers to biological sensors

The idea that quantum mechanical machines can perform certain information-processing tasks much faster than any classical computer has captured the imagination of many people. That potential has led to a new era in quantum science, one in which researchers strive to identify and harness quantum systems and leverage them for computation, communication, sensing, and imaging. Two of the most promising platforms for reaching the coherence needed to achieve such goals are isolated atoms and solid-state devices. Ions and neutral atoms can be trapped using electromagnetic fields in high vacuum, which insulates them exceptionally well from noise. And their electronic states can be precisely controlled with optical, microwave, and RF fields; that control makes them attractive as quantum bits, or qubits. Solid-state systems offer different advantages: Superconducting Josephson junctions and semiconductor quantum dots, for instance, can trap charge or spin qubit states that are spatially close enough to strongly interact. The...