Last spring an international team of researchers demonstrated that quantum computing is finally living up to its much-heralded potential. For decades scientists have been convinced that the laws of quantum physics—which describe how atomic particles can exist in two states at once, such as spinning backward and forward—could be harnessed to create a supercomputer capable of solving certain computational problems with unprecedented speed. But such particles are sensitive to environmental disturbances like heat and vibration, which cause them to “decohere,” or be robbed of their extraordinary computing powers.
For the first time, the scientists, representing the University of Southern California, Delft University of Technology in the Netherlands, Ames Laboratory at Iowa State University, and the University of California, Santa Barbara, fashioned a quantum processor that curtailed decoherence and allowed the quantum particles to perform a basic test—searching a simple dataset—at full efficiency.
A diamond was the engineers’ best friend: Vacancies in a diamond’s rigid grid of carbon molecules turned out to be a perfect place to shield atomic particles from intrusions. To process data, scientists zapped a nitrogen nucleus with radio pulses and an electron with microwaves. As lead researcher Daniel Lidar of USC explains, “We apply a pulse that flips the direction of the electron’s spin, which would have the same effect as the electron going forward and then backward in time.” The effect should be scalable to hundreds of thousands of linked atoms to create a quantum computer that is more than a laboratory curiosity.
