A team of Australian engineers at the University of New South Wales (UNSW), in Sydney, has taken the first step towards making quantum computers a reality by building a quantum logic gate in silicon for the first time.

“What we have is a game changer,” said team leader Andrew Dzurak, Scientia Professor and director of the Australian National Fabrication Facility at UNSW. “We’ve demonstrated a two-qubit logic gate – the central building block of a quantum computer – and, significantly, done it in silicon. Because we use essentially the same device technology as existing computer chips, we believe it will be much easier to manufacture a full-scale processor chip than for any of the leading designs, which rely on more exotic technologies.

“This makes the building of a quantum computer much more feasible, since it is based on the same manufacturing technology as today’s computer industry,” he added.

In classical computers, data is rendered as binary bits, which are always in one of two states: 0 or 1. However, a quantum bit (qubit) can exist in both of these states at once, a condition known as a superposition.

Until now, it had not been possible to make two qubits interact with each other using silicon. But the UNSW team, working with Professor Kohei M. Itoh of Japan’s Keio University, has done just that for the first time.

The result means that all of the physical building blocks for a silicon-based quantum computer have now been constructed, allowing engineers to begin the task of designing and building a functioning quantum computer.

The team has patented a design for a full-scale quantum computer chip that would allow for millions of qubits, all doing the types of calculations that it has experimentally demonstrated. According to Dzurak, the next step for the project is to identify the right industry partners to work with to manufacture the full-scale quantum processor chip.

A full-scale quantum processor would have major applications in the finance, security and healthcare sectors, allowing the identification and development of new medicines by greatly accelerating the computer-aided design of pharmaceutical compounds, and minimising lengthy trial and error testing; the development of new, lighter and stronger materials; and faster information searching through large databases.