Article written by Ryan Whitwam and courtesy of

The fundamental laws of the universe could spell the end of Moore’s law in the not too distant future. What is a society with rapidly increasing computational needs to do then? One answer could be to make use of quantum computing, where the quantum nature of molecules themselves are used to process data. A new experiment out of the University of Southern California (USC) might have solved one of the toughest problems in quantum computing, and it did so by building a computer inside a diamond.

This new computer isn’t going to be doing your taxes any time soon, but it shows the viability of solid-state quantum computers to lessen decoherence. Put simply, decoherence is a loss of observable information, which is the last thing you want in a computer. Digital computers are incredibly coherent — if you try to add 1 and 1, you will always get 2 — but due to decoherence, a quantum computer could return almost any result. In past liquid and gas-based systems, researchers often had to deal with decoherence as a consequence of using small, efficient particles.

The diamond computer developed at USC makes use of the impurities in the crystalline structure to make up its two quantum bits, or qubits. The CPUs you’ve always used have transistors that can represent data as a 0 or a 1. A qubit can represent a 0 and a 1 at the same time. This is thanks to the quantum property of superposition, and it’s the property that may one day make quantum computers insanely fast.

Researchers used a neutron as one qubit, and an electron as the other. This mismatched pair was used in order to accurately measure the level of decoherence. An electron, being smaller, is capable of faster calculations, but suffers more from decoherence. Neutrons are slower, but much more stable. In the experiment, scientists found that a series of microwave pulses hitting the diamond computer “reset” the particles and reduced data loss through decoherence.

USC's two-qubit diamond quantum computer chip

At this point, there is no practical application for a simple quantum computer, and no real world test to show it working. The team at USC was able to prove that they had indeed built a solid-state quantum computer by supplying it with a simple data set, and applying Grover’s algorithm, which is a mathematical proof demonstrating the potential power of quantum computers. Grover’s algorithm states that a quantum computer will be able to find a specified entry in an unsorted list on the first try, every time.

A human trying to do this would have to go down the list checking each entry to see if it was the right one. Going this route, you would on average check half the list before finding the right entry. This diamond-encrusted computer was able to find the correct choice on the first try 95% of the time, thus proving that the researchers successfully built a functional quantum computer. Cling to your silicon transistors while you can. The next step in computing is getting closer every day.


Read about IBM’s latest quantum advances (quantum computers are getting close!)

Read more at USC