Qubits based on trapped ions can be prepared and manipulated with record-breaking accuracy, offering a promising scalable platform for quantum computing.
The realization, two decades ago, that quantum mechanics can be a powerful resource to speed up important computational tasks  led to intense research efforts to find adequate physical systems for quantum computation. One of the hurdles to a viable technology is the requirement to prepare, manipulate, and measure quantum bits (qubits) with near perfect accuracy: Imperfect control leads to errors that can accumulate over the computation process. Techniques like quantum error correction and fault-tolerant designs can, in principle, overcome these errors. But these strategies can be successful only if the error probabilities are lower than a threshold value. They also increase the complexity of the required quantum hardware, since they require additional qubits. Recent calculations  suggest that an error probability of less than
The quality of qubit manipulation in a number of physical systems has dramatically improved in the past few years [3, 4], raising hopes that a quantum computer, at a large enough scale to carry out meaningful computations, might be within reach. Now, Thomas Harty at the University of Oxford, UK, and colleagues  are reporting an important contribution to this goal with the demonstration that qubits consisting of trapped