The quest to build fully functioning quantum hardware is active on many fronts. Atomic physicists have seen for some years that the quantum states of a single atom held at rest in a trap, manipulated by laser pulses, functions as a highly coherent quantum information carrier. The ability to perform elementary logic operations on such a qubit has been well demonstrated.
Unfortunately, atomic physicists are not skilled HPC designers. So, much work also goes on in the area of novel integrated-circuit devices, in which the necessary quantum control is harder to demonstrate, but from which a large-scale device could be more readily created than it could be with trapped-atom technology. Two of these efforts are represented by leading practitioners on our panel: Will Oliver is a specialist in superconducting electronics, in which quantum behavior results not because the circuits are atomic-scale, but because of the special physical properties of the superconducting state. He has interesting results on a potentially scalable Josephson-junction circuit. Another panelist, Eli Yablonovich, is an expert on the creation of qubits using individual atomic impurities in semiconductors (yes, he is also the inventor of the photonic bandgap effect). The control of individual atomic impurities and individual electrons in electronic devices has been a beautiful technological feat of recent years, which has opened up many novel possibilities, quantum and otherwise, for new, ultradense integrated devices.