Friday, October 30, 2015

Australian Researchers Design a Full-Scale Architecture for a Quantum Computer in Silicon

Australian scientists design a full-scale architecture for a quantum computer in silicon

Researchers at UNSW and the University of Melbourne have designed a 3D silicon chip architecture based on single atom quantum bits, providing a blueprint to build a large-scale quantum computer.


Sydney, Australia - Australian scientists have designed a 3D silicon chip architecture based on single atom quantum bits, which is compatible with atomic-scale fabrication techniques - providing a blueprint to build a large-scale quantum computer.

[caption id="attachment_687" align="aligncenter" width="695"]Australian Researchers design a full-scale architecture for a quantum computer in silicon This picture shows from left to right Dr Matthew House, Sam Hile (seated), Scientia Professor Sven Rogge and Scientia Professor Michelle Simmons of the ARC Centre of Excellence for Quantum Computation and Communication Technology at UNSW.[/caption]

Scientists and engineers from the Australian Research Council Centre of Excellence for Quantum Computation and Communication Technology (CQC2T), headquartered at the University of New South Wales (UNSW), are leading the world in the race to develop a scalable quantum computer in silicon - a material well-understood and favoured by the trillion-dollar computing and microelectronics industry.

Teams led by UNSW researchers have already demonstrated a unique fabrication strategy for realising atomic-scale devices and have developed the world's most efficient quantum bits in silicon using either the electron or nuclear spins of single phosphorus atoms. Quantum bits - or qubits - are the fundamental data components of quantum computers.

One of the final hurdles to scaling up to an operational quantum computer is the architecture. Here it is necessary to figure out how to precisely control multiple qubits in parallel, across an array of many thousands of qubits, and constantly correct for 'quantum' errors in calculations.

Now, the CQC2T collaboration, involving theoretical and experimental researchers from the University of Melbourne and UNSW, has designed such a device. In a study published today inScience Advances, the CQC2T team describes a new silicon architecture, which uses atomic-scale qubits aligned to control lines - which are essentially very narrow wires - inside a 3D design.

"We have demonstrated we can build devices in silicon at the atomic-scale and have been working towards a full-scale architecture where we can perform error correction protocols - providing a practical system that can be scaled up to larger numbers of qubits," says UNSW Scientia Professor Michelle Simmons, study co-author and Director of the CQC2T.

"The great thing about this work, and architecture, is that it gives us an endpoint. We now know exactly what we need to do in the international race to get there."

In the team's conceptual design, they have moved from a one-dimensional array of qubits, positioned along a single line, to a two-dimensional array, positioned on a plane that is far more tolerant to errors. This qubit layer is "sandwiched" in a three-dimensional architecture, between two layers of wires arranged in a grid.

About the video - Australian researchers have figured out a way to deal with errors in quantum computers, giving them the essential architecture that may help this team become the first to build a functioning quantum computer in silicon.

By applying voltages to a sub-set of these wires, multiple qubits can be controlled in parallel, performing a series of operations using far fewer controls. Importantly, with their design, they can perform the 2D surface code error correction protocols in which any computational errors that creep into the calculation can be corrected faster than they occur.

"Our Australian team has developed the world's best qubits in silicon," says University of Melbourne Professor Lloyd Hollenberg, Deputy Director of the CQC2T who led the work with colleague Dr Charles Hill. "However, to scale up to a full operational quantum computer we need more than just many of these qubits - we need to be able to control and arrange them in such a way that we can correct errors quantum mechanically."

"In our work, we've developed a blueprint that is unique to our system of qubits in silicon, for building a full-scale quantum computer."

In their paper, the team proposes a strategy to build the device, which leverages the CQC2T's internationally unique capability of atomic-scale device fabrication. They have also modelled the required voltages applied to the grid wires, needed to address individual qubits, and make the processor work.

"This architecture gives us the dense packing and parallel operation essential for scaling up the size of the quantum processor," says Scientia Professor Sven Rogge, Head of the UNSW School of Physics. "Ultimately, the structure is scalable to millions of qubits, required for a full-scale quantum processor."

News Release Source :  Australian scientists design a full-scale architecture for a quantum computer in silicon

Image Credit : UNSW Australia

Tuesday, October 6, 2015

Australian Engineers Build World First Two-Qubit Logic Gate in Silicon

Crucial hurdle overcome in quantum computing

UNSW, 06 OCT 2015

A team of Australian engineers has built a quantum logic gate in silicon for the first time, making calculations between two qubits of information possible – and thereby clearing the final hurdle to making silicon quantum computers a reality.

A team of Australian engineers has built a quantum logic gate in silicon for the first time, making calculations between two qubits of information possible – and thereby clearing the final hurdle to making silicon quantum computers a reality.

[caption id="attachment_677" align="aligncenter" width="563"]Australian Engineers Build World First Two-Qubit Logic Gate in Silicon Lead author Menno Veldhorst (left) and project leader Andrew Dzurak (right) in the UNSW laboratory where the experiments were performed.[/caption]

The significant advance, by a team at the University of New South Wales (UNSW) in Sydney appears today in the international journal Nature.

“What we have is a game changer,” said team leader Andrew Dzurak, Scientia Professor and Director of the Australian National Fabrication Facility at UNSW.

“We’ve demonstrated a two-qubit logic gate – the central building block of a quantum computer – and, significantly, done it in silicon. Because we use essentially the same device technology as existing computer chips, we believe it will be much easier to manufacture a full-scale processor chip than for any of the leading designs, which rely on more exotic technologies.

“This makes the building of a quantum computer much more feasible, since it is based on the same manufacturing technology as today’s computer industry,” he added.

The advance represents the final physical component needed to realise the promise of super-powerful silicon quantum computers, which harness the science of the very small – the strange behaviour of subatomic particles – to solve computing challenges that are beyond the reach of even today’s fastest supercomputers.

In classical computers, data is rendered as binary bits, which are always in one of two states: 0 or 1. However, a quantum bit (or ‘qubit’) can exist in both of these states at once, a condition known as a superposition. A qubit operation exploits this quantum weirdness by allowing many computations to be performed in parallel (a two-qubit system performs the operation on 4 values, a three-qubit system on 8, and so on).

“If quantum computers are to become a reality, the ability to conduct one- and two-qubit calculations are essential,” said Dzurak, who jointly led the team in 2012 that demonstrated the first ever silicon qubit, also reported in Nature.

Until now, it had not been possible to make two quantum bits ‘talk’ to each other – and thereby create a logic gate – using silicon. But the UNSW team – working with Professor Kohei M. Itoh of Japan’s Keio University – has done just that for the first time.

The result means that all of the physical building blocks for a silicon-based quantum computer have now been successfully constructed, allowing engineers to finally begin the task of designing and building a functioning quantum computer.

"Despite this enormous global interest and investment, quantum computing has – like Schrödinger’s cat – been simultaneously possible (in theory) but seemingly impossible (in physical reality),” saidProfessor Mark Hoffman, UNSW's Dean of Engineering.

“The advance our UNSW team has made could, we believe, be the inflection point that changes that Schrödinger’s paradigm," he added. "The technology – devised, tested and patented by our team – has the potential to take quantum computing across the threshold from the theoretical to the real.”

A key advantage of the UNSW approach is that it reconfigured the ‘transistors’ used to define the bits in existing silicon chips, and turned them into qubits. “The silicon chip in your smartphone or tablet already has around one billion transistors on it, with each transistor less than 100 billionths of a metre in size,” said Dr Menno Veldhorst, a UNSW Research Fellow and the lead author of the Nature paper.

“We’ve morphed those silicon transistors into quantum bits by ensuring that each has only one electron associated with it. We then store the binary code of 0 or 1 on the ‘spin’ of the electron, which is associated with the electron’s tiny magnetic field,” he added.

Dzurak noted that the team had recently “patented a design for a full-scale quantum computer chip that would allow for millions of our qubits, all doing the types of calculations that we’ve just experimentally demonstrated".

He said that a key next step for the project is to identify the right industry partners to work with to manufacture the full-scale quantum processor chip.

Such a full-scale quantum processor would have major applications in the finance, security and healthcare sectors, allowing the identification and development of new medicines by greatly accelerating the computer-aided design of pharmaceutical compounds (and minimising lengthy trial and error testing); the development of new, lighter and stronger materials spanning consumer electronics to aircraft; and faster information searching through large databases.

Other researchers from UNSW’s School of Electrical Engineering and Telecommunications who contributed to the work include Dr Henry Yang and Associate Professor Andrea Morello, who leads the quantum spin control research team. Professor Kohei M. Itoh from Keio University in Japan provided specialised silicon wafers for the project.

Dzurak’s research is supported by the Australian Research Council via the Centre of Excellence for Quantum Computation and Communication Technology, the U.S. Army Research Office, the State Government of New South Wales in Australia, the Commonwealth Bank of Australia, and the University of New South Wales. Veldhorst acknowledges support from the Netherlands Organisation for Scientific Research. The quantum logic devices were constructed at the Australian National Fabrication Facility, which is supported by the federal government’s National Collaborative Research Infrastructure Strategy (NCRIS).

News Release Source : Crucial hurdle overcome in quantum computing

Image Credit : University of New South Wales (UNSW)