Quantum computing with superconductors

Superconductive technology is one of the most promising approaches to quantum computing because it offers devices with little dissipation, ultrasensitive magnetometers, and electrometers for state readout, large-scale-integration, and a family of classical electronics that could be used for quantum bit (qubit) control. The challenges this technology faces, however, are substantial: for example, control of the qubit to a part in ∼10⁴ must be accomplished with analog control pulses. But even after this is done, the accuracy is limited by the unavoidable decay of quantum information in the system. Recent experiments suggest the time over which this decay occurs is <1 μs, though it is expected to lengthen as experimental methods improve. A 1-μs decay time would mandate a very difficult to achieve maximum time of ∼100 ps per analog operation. Thus, quantum computing is, simultaneously a promising technology for solving certain very hard problems in computer science and a daunting challenge for those working to develop that technology.