Error reduction marks breakthrough in quantum computing

"One error per 10,000 logic operations is a commonly agreed upon target for a low enough error rate to use error correction protocols in a quantum computer," explained postdoctoral researcher Kenton Brown, who led the project. Brown continued: "It is generally accepted that if error rates are above that, you will introduce more errors in your correction operations than you are able to correct. We've been able to show that we have good enough control over our single qubit operations that our probability of error is 1 per 50,000 logic operations." The NIST experiment was performed on 1,000 unique sequences of logic operations randomly selected by computer software. Sequences of 10 different lengths, ranging from one to 987 operations, were repeated 100 times each and the measured results were compared to perfect theoretical outcomes. The maximum length of the sequences was limited by the hardware used to control the experiment. According to Brown, the record low error rate was made possible by two major changes in the group's experimental setup. First, the scientists manipulated the ion using microwaves instead of the usual laser beams. A microwave antenna was incorporated into the ion trap, with the ion held close by, hovering 40 micrometers above the trap surface. The use of microwaves was said to reduce errors caused by instability in laser beam pointing and power, as well as spontaneous ion emissions. Secondly, the ion trap was placed inside a copper vacuum chamber and cooled to 4.2K with a helium bath. Brown noted that this reduced the errors caused by magnetic field fluctuations in the lab. The research was supported in part by the Intelligence Advanced Research Projects Activity, the National Security Agency, the Defense Advanced Research Projects Agency and the Office of Naval Research.