Science //

Quantum quandaries

Rupert Coy investigates the Marcus Einfeld phenomenon.

Things can be in two places at once. This is quite possibly the most extraordinary conclusion in modern science. It seems wrong, it goes against every last bit of intuition, but it’s now an accepted part of physics. Although unobservable at the level of human beings, the principles of quantum physics can be seen in particles like electrons and photons. Now scientists at Sydney University and across the globe are using this phenomenon to create the first quantum computers (QCs).

It’s both unusual and incredibly exciting that many possibilities of QCs are already clear. Often, revolutionary technologies have been completely unexpected: the first researchers of semiconductors had no idea that it would develop into a $300 billion electronics industry. Likewise, it took decades after the first investigation into microwaves was done for scientists to realise that they could be used to heat up last night’s pizza.

Security is at the forefront of this research. Sydney University’s Professor Stephen Bartlett, a primary investigator in the Quantum Science Group, said that he now saw “a direct application for problems in cryptography and data security”. The most important of these is the RSA cryptosystem, which is not only used for encrypting emails and other digital information on the internet, but is also fundamentally similar to some encryption used by the NSA, British Secret Service, and other intelligence agencies.

According to Professor Bartlett, QCs also have a future in ‘big data’: huge sets of information found in fields like climatology, finance and medicine. Modern computers are ill-equipped to process such enormous amounts of data, but the sheer power of QCs could allow them to more efficiently analyse this information and aid in the production of cancer drugs or real-time fraud prevention.

Two remarkable properties set QCs apart from any computers before them. The first, superposition, allows for several possible events to occur simultaneously, like a single particle being in two places at once. The most basic repercussions of this in computing is that instead of machines consisting of bits, which are either 0 or 1, QCs have qubits which can represent 0 and 1 at the same time. This seemingly innocuous change makes an extraordinary difference. It takes more than a terabyte (around 8,800,000,000,000 bits) on today’s computers to describe a system with just five hundred qubits.

The second phenomenon is entanglement, which describes how particles are inherently related to one another. Scientists use this to create quantum logic gates, which connect parts of a computer that were completely disparate in normal integrated circuits. This means that QCs should be able tackle a far broader range of computational problems than normal machines ever could.

Despite rapid progress, QC research remains in its early stages. Professor Bartlett explains: “There are still many open questions, such as what are the key aspects of quantum mechanics that allow us to process information in a way that a conventional computer cannot?” Promisingly, the physical difficulties of compiling a QC, which seemed insurmountable even in the 1980s, are slowly being overcome. Sydney University is playing a key role in this, says Professor Bartlett. “We are solving physical and engineering problems on how to build and operate the basic components of a QC … this is very much a frontier field of discovery.”

When will we have fully-functioning QCs? The timescale depends often just as much on the political and social will as it does on the scientists. The sharp rises and declines of space exploration, a result largely down to the oscillating NASA budget, shows as much. Nonetheless, Professor Bartlett predicts that within the next decade QCs will feature in scientific and industrial research. A growing interest in the security and technological implications of QCs should provide a catalyst for further research. Exciting times.