Computing with Entangled Ions

Quantum computing typically involves manipulating quantum bits of information without observing them—at least until the final readout. An alternative strategy is to measure qubits throughout the process, and use each observation as part of the computation. Previous experiments in measurement-based quantum computing (MBQC) have used photons, which are hard to prepare in large numbers. Now, for the first time, researchers have performed MBQC with trapped ions. As reported in Physical Review Letters, the team entangled several ionic qubits and then demonstrated a set of basic ion measurements that can be combined to produce any arbitrary computation.