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The quantum future is crystal clear: Tiny crystal revolutionises computing



26 April 2012

Computing technology has taken a huge leap forward thanks to a tiny crystal of trapped ions used in experiments by Dr Michael Biercuk, from the University of Sydney's School of Physics and ARC Centre of Excellence for Engineered Quantum Systems, with US and South African colleagues.

The ion-crystal is poised to become one of the most powerful computers yet developed, with the results published in the prestigious journal Nature on 26 April 2012.

Dr Michael Biercuk, from the University of Sydney's School of Physics and ARC Centre of Excellence for Engineered Quantum Systems, with US and South African colleagues, has created a tiny crystal of trapped ions that is poised to become one of the most powerful computers yet developed.
Dr Michael Biercuk, from the University of Sydney's School of Physics and ARC Centre of Excellence for Engineered Quantum Systems, with US and South African colleagues, has created a tiny crystal of trapped ions that is poised to become one of the most powerful computers yet developed.

Smashing previous records in terms of the number of atoms working together in a functioning quantum simulator, the new crystal will enable a new class of quantum computer capable of performing calculations that currently stump the world's most powerful supercomputers.

"The system we have developed has the potential to perform calculations that would require a classical machine larger than the size of the known universe - and it does it all in a diameter of less than a millimetre," said Dr Michael Biercuk.

The team Dr Biercuk worked with, including scientists from the US National Institute of Standards and Technology, Georgetown University in Washington, North Carolina State University and the Council for Scientific and Industrial Research in South Africa, has produced a specialised kind of quantum computer known as a 'quantum simulator', which uses a well controlled quantum device to mimic another system that is not understood.

Ever since Nobel Prize winner Richard Feynman highlighted the potential of quantum computing in the 1980s, scientists have been attempting to build quantum computers capable of solving some of the largest and most complex problems. In particular, Feynman recognised the tremendous potential for special-purpose quantum simulators to solve a variety of challenging problems in materials science, chemistry and biology, with much greater efficiency than conventional computers.

Previous attempts at creating similar quantum simulators have achieved experimental demonstrations with up to 16 interacting spins, each carrying quantum information as a quantum bit or 'qubit'.

In comparison, Dr Biercuk and team's revolutionary crystal has 300 beryllium ions with interacting spins, exceeding not only previous experimental attempts, but also the important threshold of 30-40 qubits needed to exceed the capabilities of most supercomputers.

"Many properties of natural materials governed by the laws of quantum mechanics are very difficult to model using conventional computers. The key concept in quantum simulation is building a well characterised and controlled quantum system to provide insights into the behaviour of other naturally occurring physical systems," said Dr Biercuk.

"Much like studying a scale model of an airplane wing in a wind tunnel to simulate the behaviour of a full-scale aircraft, we can glean tremendous insights about difficult and complex quantum systems using our own quantum 'scale model'."

Quantum computing revolution: The new quantum crystal is made of a two dimensional layer of beryllium ions hovering in space within a Penning trap.
Quantum computing revolution: The new quantum crystal is made of a two dimensional layer of beryllium ions hovering in space within a Penning trap.

The new crystal - made of a two dimensional layer of beryllium ions hovering in space within a Penning trap - provides exceptional new capabilities.

Each beryllium ion has a single outer electron that acts as a tiny quantum magnet - known as a 'spin'. By applying carefully timed laser and microwave pulses, the researchers can engineer interactions between these spins in order to mimic interactions found in natural materials. They can even realise interactions that are not known to be found in nature, engineering totally new forms of quantum matter.

"By engineering precisely controlled interactions and then studying the output of the system, we are effectively running a 'program' for the simulation. The unprecedented tunability and scale of our device allows us to run a wide variety of interesting programs," explained Dr Biercuk.

"In our case, we are studying the interactions of spins in the field of quantum magnetism - a key problem that underlies new discoveries in materials science for energy, biology, and medicine," said Dr Biercuk.

"For instance, we hope to study the spin interactions predicted by models for high-temperature superconductivity - a physical phenomenon that has yet to be explained, but has the potential to revolutionise power distribution and high-speed transport."

While 300 qubits may not sound like much compared to the billions of transistors in desktop computers, in quantum systems the amount of information that can be processed scales exponentially with the number of qubits. The amount of information that can be processed in the team's new experimental crystal approaches the level of a googol - a huge number worth 10 to the power of 100. (And, yes, it's the basis for the name of that well-known company.)

Making a googol-sized classical computer is next to impossible, because it would be the size of the entire known universe. Now all of that computational power resides inside a tiny crystal of trapped ions, less than a millimetre in diameter.

Read the paper in Nature at: www.nature.com/nature/journal/v484/n7395/full/nature10981.html


Contact: Katynna Gill

Phone: 02 9351 6997

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