UNSW research leads quantum computing race
Scientists from the University of New South Wales (UNSW) are making science fiction a reality. They are manipulating matter at the most fundamental level, with the aim of building a powerful new kind of computer.
In their mind, the next generation of computer will operate using the laws of quantum physics and will unlock unimaginable processing power to solve problems beyond the capacity of today’s technology.
When it comes to understanding quantum computing, most of us are familiar with ‘bits’ – the fundamental units of information regular computers are based upon. The billions of bits inside your laptop or other computers are encoded using transistors on integrated circuits. They can have two possible values – 1 or 0 – depending on whether electrical current flows through them.
In the 1980s, scientists began to theorise it might be possible to build computers a completely different way, harnessing the special properties of matter that apply when you get down to the sub-atomic scale. In this minuscule world, objects can simultaneously exist in a combination of all their possible states, in a phenomenon known as superposition. Scientists realised if they could make computers that stored information in these kinds of quantum systems, then each ‘quantum bit’ of information, or qubit, could be, in essence, a 0 and 1 simultaneously.
Another quantum phenomenon vital in quantum computing is ‘entanglement’. Put simply, this phenomenon means the characteristics of two particles that have interacted with each other become inextricably linked. So if you measure a property of one of them, the others will be found to have values that correlate.
Together these two quantum properties promise to change the arithmetic of computing completely. Scientists realised as you added more and more entangled qubits together, the computing power would grow exponentially.
This would allow a quantum computer to compute many different possible solutions to certain kinds of problems all at once. While a regular computer needs to take a certain number of steps in order to calculate something, a quantum computer would be capable of taking huge short cuts by performing its calculations in parallel across all its entangled qubits.
Every year, scientists discover more and more potential applications for quantum computers, explains Scientia Professor of Physics and Laureate Fellow Michelle Simmons, named NSW Scientist of the Year in 2011.
“A lot of the applications are mathematical, such as economic modelling, financial modelling and weather forecasting,” revealed Scientia Professor Simmons.
Other applications might include searching through large amounts of data, simulating natural phenomena and calculating the factors of very large numbers.
“There are mathematicians, theoretical physicists and computer scientists all over the world working on the development of these algorithms, although most people aren’t necessarily aware of it. If a quantum computer can do something in a week that would normally take two years, then suddenly everything changes,” added Simmons.
The quantum computing researchers at UNSW are all part of the interstate Centre for Quantum Computation and Communication Technology (CQC2T).
In recent years, they have published a series of important articles in the world’s top scientific journals that showed that using phosphorus atoms in silicon was an ideal way to build qubits.
The UNSW teams, led by Scientia Professor Simmons, Professors Sven Rogge, Andrea Morello and Andrew Dzurak, have different methods to prepare these phosphorus atom qubits.
To understand where quantum researchers are currently at, it’s helpful to think about the development of silicon-based chips in regular computers.
Making this comparison, Scientia Professor Simmons said it took about 15 years from a single transistor to having a product you could sell.
“In quantum computing that’s where we are, in that period.”
The difference is that while most people in the 1950s and 1960s were working on integrated circuits built on silicon chips, in quantum computing there are many different quantum computer ‘architectures’ being studied by different research groups around the world.
“There are all these different approaches, and some of them just aren’t going to scale. The game really is what is going to scale up, to lead to a practical system. Silicon is definitely the one we are betting on and, motivated by our results, a lot of people are now moving into this space,” explained Simmons.
To make the leap to a useful, commercially saleable computer, the UNSW scientists need to build a method of combining multiple qubits into an architecture that allows them to communicate with each other.
*A version of this article first appeared in UNSW’s Uniken magazine.