Laser-cooled atomic ions are standards for quantum information science, as qubits that have unsurpassed levels of quantum coherence and can be measured with near-perfect efficiency. When state-dependent optical dipole forces are applied to a collection of atomic ions, their Coulomb interaction is modulated in a way that allows the entanglement of the qubits through quantum gates. Similar forces allow the simulation of quantum magnetic interactions, and recent experiments have implemented a transverse Ising model with up to 16 trapped ions, the largest collection of interacting qubits yet demonstrated. Soon the number of spins in the system will be high enough where no classical computer can predict its behavior. Scaling to even larger numbers can be accomplished by coupling trapped ion qubits to photons, where entanglement can be formed over remote distances for applications in quantum communication, quantum teleportation, and distributed quantum computation.
10 Minute Talk: Time-resolved magnetic sensing with electronic spins in diamond