Image 1 - Researchers Create Quantum Computer In Diamond
April 6, 2012

Researchers Create Quantum Computer In Diamond

A girl's best friend has stepped into the digital age as scientists from the University of Southern California have built a quantum computer inside a diamond.

The scientists reported in the journal Nature on Thursday that their diamond quantum computer system features two quantum bits, or qubits, made of subatomic particles.

Qubits are able to encode a one and a zero at the same time, compared to traditional computer bits, which encode distinctly either a one or a zero.

Being able to perform this task will one day enable computers to perform optimization calculations much faster than traditional computers.

Current quantum computers are small, and are unable to compete with the speed of larger, traditional computers.  In order for quantum computing in a diamond to become the next option for computing, USC Professor Daniel Lidar said the computer must be scaled up.

"Our work is an in-principle demonstration of the potential of quantum computing in diamond," Lidar told RedOrbit.

Superposition, along with the ability of quantum states to "tunnel" through energy barriers, could one day allow quantum computers to perform optimization calculations faster than traditional computers.

The team said they were able to utilize the impurities of the diamond during their project.  Impurities in a diamond are considered things other than carbon.

"Diamond is a near perfect material," Lidar told RedOrbit. "Its extreme purity means that our qubits experienced a nearly pristine environment, which allowed them to retain their quantumness for relatively long times compared to other materials."

The researchers used a rogue nitrogen nucleus to become the first qubit, and an electron to become the second qubit.

Electrons are smaller than nuclei and perform computations quicker, but fall victim more quickly to "decoherence."  A qubit that is based on a nucleus is much more stable, but is 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.

The team was able to demonstrate that their diamond-encased system operates in a quantum fashion by seeing how closely it matched "Grover's algorithm." Lov Grover of Bell Labs invented the algorithm in 1996, which shows the promise of quantum computing.

During this test, a computer searches for an unsorted database, an example of which the researchers said is like being told to search for a name in a phone book when someone has only been given a number.

Quantum computers can find the correct choice quicker than traditional computers, and the researchers found that their diamond computer was able to pick the correct choice on the first try about 95 percent of the time.

Lidar said that their diamond computer could one day have benefits in almost any research.

"If and when quantum computing in diamond is scaled up to much larger numbers of qubits, the research potential is virtually unlimited, and applications could range from cryptography to computer aided design of brand new materials," he told RedOrbit.

However, he said it is still too early to consider mass production for the diamond quantum computer.


Image 2: The diamond in the center measures 1 mm X 1 mm. Photo/Courtesy of Delft University of Technolgy/UC Santa Barbara