Electrons are smaller than nuclei and perform computations much more quickly, but also fall victim more quickly to "decoherence." A qubit based on a nucleus, which is large, is much more stable but slower.
"A nucleus has a long decoherence time in the milliseconds. You can think of it as very sluggish," said Lidar, who holds a joint appointment with the USC Viterbi School of Engineering and the USC Dornsife College of Letters, Arts and Sciences.
Though solid-state computing systems have existed before, this was the first to incorporate decoherence protection using microwave pulses to continually switch the direction of the electron spin rotation.
"It's a little like time travel," Lidar said, because switching the direction of rotation time-reverses the inconsistencies in motion as the qubits move back to their original position.
The team was able to demonstrate that their diamond-encased system does indeed operate in a quantum fashion by seeing how closely it matched "Grover's algorithm."
The algorithm is not new Lov Grover of Bell Labs invented it in 1996 but it shows the promise of quantum computing.
The test is a search of an unsorted database, akin to being told to search for a name in a phone book when you've only been given the phone number.
Sometimes you'd miraculously find it on the first try, other times you might have to search through the entire book to find it. If you did the search countless times, on average, you'd find the name you were looking for after searching through half of the phone book.
Mathematically, this can be expressed by saying you'd find the correct choice in X/2 tries if X is the number of total choices you have to search through. So, with four choices total, you'll find the correct one after two tries on average.
A quantum computer, using the properties of superposition, can find the correct c
|Contact: Robert Perkins|
University of Southern California