Quantum Computers One Step Closer After Australian Breakthrough


Dr. Alfredo Carpineti

Senior Staff Writer & Space Correspondent

clockNov 18 2015, 18:50 UTC
3786 Quantum Computers One Step Closer After Australian Breakthrough
Visualization of an entangled quantum state that represents a single computer code. Tony Melov/UNSW

Engineers from the University of New South Wales, Australia, have made an important breakthrough that brings quantum computers one step closer to reality.


The team created a quantum version of a standard computer code within a silicon chip. The discovery shows that it is possible to construct realistic and reliable quantum computers.

Quantum computers have the potential to solve problems much more quickly than any computer that exists today, as they combine the rules of informatics to phenomena of quantum mechanics that are not observed in everyday life. Namely, the principle of superposition, popularized by Schrödinger’s cat being both alive and dead, and entanglement.

The specific test conducted in Australia used entanglement to run the code. Entangled particles are created together in a specific way so that their properties, such as energy and momentum, are connected. If a property is changed on one particle, for example during a measurement, the others will be affected as well. The changes are instantaneous, even if the two particles are at opposite ends of the universe, so scientists thought that it might be a violation of special relativity, which dictates that information cannot travel faster than light. Recently, it has been demonstrated that entanglement is a real phenomenon, though.

Using quantum behaviors adds more capability to computing. "This is, in some sense, the reason why quantum computers can be so much more powerful," said Stephanie Simmons, co-author of the study, in a statement. "With the same number of bits, they allow us to write a computer code that contains many more words, and we can use those extra words to run a different algorithm that reaches the result in a smaller number of steps."


The experiment consisted of creating an entangled state between the nucleus of a phosphorus atom and a single electron within a silicon chip. The phosphorus and the electron form a qubit, the quantum equivalent of a computer bit, and the experiment showed that they can be easily controlled and used for operations. While a conventional bit has only two possible states – 0 and 1 – qubits have many more thanks to quantum mechanics, which is why quantum computers are expected to be significantly more powerful than the computers we have today. 

"Now, we have shown beyond any doubt that we can write this code inside a device that resembles the silicon microchips you have on your laptop or your mobile phone," said Professor Andrea Morello, leader of the team. "It's a real triumph of electrical engineering."

The research is published in Nature Nanotechnology.

  • quantum superposition,

  • entanglement,

  • quantum computers