Quantum Science and Technology , 3, 3 (2018)
For the last two decades, scientists and engineers have explored, and often invented, new avenues in what we now call the second quantum revolution—the capacity to create novel and tailored functionalities using natural or artificial quantum systems. The construction of a functional, scalable, useful quantum computer remains one of the most sought-after goals in this exciting field. From the first embryonic demonstrations of controlled quantum operations with trapped ions, photons and superconducting circuits, we have now reached the point where dozens of qubits can be operated with gate fidelities approaching or surpassing some thresholds for quantum error correction. The investment in the field is ramping up at a tantalizing speed, with many large technology companies working alongside academia and basic research labs to achieve the next milestone.