The real quantum of computing

Written by Pratik Kanjilal | Updated: Dec 5 2013, 11:02am hrs
Quantum computers are the next big wave, machines capable of performing certain tasks like running queries over a database at speeds that are orders of magnitude faster than current computers can achieve. A paper in the journal Nature Photonics reports the development of the biggest ever, multiplexing 10,000 photons, each functioning as a holder for a quantum data bit or qubit. This was a computer built out of laser light, and the best-performing forerunner in its class was capable of only eight qubits. The best quantum computer ever, built out of ions in a droplet of fluid, offered 14 qubits. So, does this ground-breaking project of the Australian National University and Tokyo University mean that the future is upon us Alas, not right away.

Quantum computing will be transformative in ways that we cannot imagine today, but the great disruption is still decades away. Some researchers fear that it will remain forever on the drawing board and David Deutsch, one of the founders of the concept, believed that the quantum computer is valuable as just that: a concept which urges researchers to think about data and computing in novel ways. However, the Australian project brings quantum computing much nearer the realm of the possible. While earlier machines could solve sudokus but were intellectual midgets in the real world, this project has demonstrated scalability and could pave the way to true artificial intelligence.

But first, the essentials of quantum computing. Long before it was a physical reality, the computer was theoretically described by Alan Turing as an endless tape bearing frames, like cine film. Each frame can hold either nothing or the digits one and zero, the binary number set. Reading these in sequence, the machine picks up data and instructions on how to manipulate it. The modern computer works on the Turing model. The only structural improvement is parallel processing, which allows the machine to read and write multiple frames at once, the basic attribute of a supercomputer.

But the quantum computer represents a whole new generation. Quantum country is the land of shape-shifters. Using the property of superposition, an entity can exist in multiple states. While regular-world bits must be either zero or one, quantum bits can be both, and every value in between, in the very same moment. Just as Schrdingers cat was both dead and alive until the observer actually looked at it. This offers a quantum system, whose elements function as the processor and memory of a computer, the ability to manipulate data in a natively and massively parallel manner. That problematic cat also illustrated a serious stumbling block in building a quantum computer: observing a system changes its state. The cat was both dead and alive until the observer looked at it. Upon observation, it had to take on a specific state, either dead or alive. To avoid interfering with the system, entanglement, a quantum property first discussed by Schrdinger, is used. To control processes and read output, the machine works at one remove, interacting with quantum objects which interact with components of the machine.

Ironically, while the quantum computer that can serve as a desktop replacement or run an internet server may be decades away, its development is made inevitable by Moores Law. In a 1965 paper, Intel co-founder Gordon E Moore suggested that the density of transistors on integrated circuits doubles every two years. Later, the rate was redefined as a doubling of computing capability every 18 months, on the basis of Intel executive David Houses observation that along with density, the growing speed of components was a factor.

But a rise in component density on a chip implies that in inverse proportion, the size of components and the paths between them is falling. Moores Law is perceived to have slackened off recently, operating over a timeframe of three years. But even so, in less than a decade, the sizes of chip components and paths should have fallen to quantum levels, whereupon quantum behaviour should become visible in computers. Willy-nilly, the quantum computer could be here.

What would be its effects First, the big data industry would explode as quantum machines mine data in unprecedented ways at unprecedented speeds to uncover previously undiscoverable patterns. This would encourage the collection of even more data than ever before to fuel a new growth sector. Second, privacy would be dead. The encryption methods in use now like the RSA algorithm, an old and reliable war-horse of asymmetric encryption, take so much time to crack that the effort is pointless. However, a quantum machine could conceivably crack them in real time and no form of secret communication would be possible across the internet, not even encrypted voice calls.

But it is too early to speculate. The creators of the computer did not know that the internet was coming. Today, we have no idea what the next generation of computing will create.