In the future, quantum computers will accomplish in seconds what would take years with our best computers today. Physicists at NIST have made a significant leap towards this goal by demonstrating the first "universal" programmable quantum information processor.
In other words, this is the first time anyone has developed a processor that can handle any set of instructions for more than one quantum bit or "qubit". Rapid progress when you consider that the first single-task quantum processorfirst arrived on the scene less than a year ago.
The NIST team performed 160 different processing routines on the two qubits. Although there are an infinite number of possible two-qubit programs, this set of 160 is large and diverse enough to fairly represent them, Hanneke says, making the processor "universal." The researchers used a random number generator to select the particular routines that would be executed, so all possible programs had an equal chance of selection. The random programs avoided the possibility of bias in testing the processor in the event that some programs ran better or produced more accurate outputs than others. Each program operated accurately an average of 79 per cent of the time across 900 runs, each run lasting about 37 milliseconds. To evaluate the processor and the quality of its operation, NIST scientists compared the measured outputs of the programs to idealised, theoretical results.
The programs did not perform easily described mathematical calculations. Rather, they involved various single-qubit "rotations" and two-qubit entanglements. As an example of a rotation, if a qubit is envisioned as a dot on a sphere at the north pole for 0, at the south pole for 1, or on the equator for a balanced superposition of 0 and 1, the dot might be rotated to a different point on the sphere, perhaps from the northern to the southern hemisphere, making it more of a 1 than a 0.
Huh? Yeah, it's a bit confusing, but you can get the basic idea by checking out our Giz Explains on the subject. Just know that programming with multiple qubits is a major turning point in creating the truly "super" computers of tomorrow. [NIST and Ars Technica]