by Byron Connolly

Australian researchers create world’s first working quantum bit

Sep 20, 20123 mins
Technology Industry

Researchers at the University of New South Wales have created the world’s first working quantum bit based on a single atom in silicon, which they claim will lead to the development of ultra-powerful computers in the future.

In a paper published in scientific journal Nature, the research team described how it was able to both read and write information using the spin, or magnetic orientation, of an electron bound to a single phosphorous atom embedded in a silicon chip.

This enabled them to form a quantum bit or “qubit”, the basic unit of data for quantum computers, which promise to solve complex problems “that are currently impossible on even the world’s largest supercomputers,” according to team leader Dr Andrea Morello.

“These include data-intensive problems, such as cracking modern encryption codes, searching databases and modelling biological molecules and drugs.”

The team was led by Dr Morello and Professor Andrew Dzurak from the UNSW School of Electrical Engineering and Telecommunications and also included researchers from the University of Melbourne and University College, London.

The paper’s lead author, UNSW PhD student Jarryd Pla, said researchers had been able to “isolate, measure and control an electron belonging to a single atom, all using a device that was made in a very similar way to everyday silicon computer chips.”

According to Dr Morello: “This is quantum equivalent of typing a number on your keyboard. This has never been done before in silicon, a material that offers the advantage of being well understood scientifically and more easily adopted by industry.”

In 2010, the same UNSW group demonstrated the ability to read the state of an electron’s spin and discovering how to “write the spin state” completes the two-stage process required to operate a quantum bit, according to the university.

The new result was achieved by using a microwave field to gain control over an electron bound to a single phosphorous atom, which was implanted next to a specially designed silicon transistor.

The research team’s next goal is to combine pairs of quantum bits to create a two-qubit logic gate – the basic processing of a quantum computer.

The news follows UNSW’s announcement in February that it had successfully created a single-atom transistor, which could be used as a “building block” for quantum computing.

UNSW is not alone in the field of quantum computing research in Australia and Asia. In August, the Australian National University, the National University of Singapore and the University of Queensland said background interference in quantum-level measurements may be the key to unlocking quantum computing’s potential. The interference is known as “quantum discord.”

Previously, it was believed that “quantum entanglement” – where sub-atomic particles become so entwined that they share the same properties even if they are separated – was the only way to realise quantum technologies.