“Quantum computers: how and why”
Andrea Morello
Professor of Quantum Engineering
UNSW Sydney
Wednesday 5 July 2017
Union, University and Schools Club, 25 Bent Street, Sydney
The talk certainly lived up to its promise of giving an excellent insight into a subject that, for most of the audience, would be far removed from their professional knowledge and experience. Starting out with a simple demonstration of how quantum effects are size dependent, Andrea went on to describe some of the current realisations of quantum devices that can manipulate one bit of information – a qubit – and, in particular, the device pioneered by his group, which uses the coupling between the nuclear and electron spin of a phosphorus atom in silicon. However, a single qubit device is, in principle, functionally no different from a single memory cell in a normal silicon chip. The big difference between current computers and a quantum computer arises through the effect of entanglement, which allows N entangled qubits to be manipulated as a single entity with 2N states (a memory chip with N cells can also store any one of 2N different “words”, but such a word can only be changed bit by bit). The promise of enormously enhanced computing power is currently being pursued in a number of corporations, including Google, IBM, and Lockheed Martin, and here in Australia a consortium of Andrea’s group at UNSW, Telstra, and CBA, with Government support, is being created to stay in the race – the Royal Society of NSW wishes them lots of success. The great interest in Andrea’s presentation was demonstrated by the vigorous Q&A session that followed, which explored some of the challenges