Saturday, December 16, 2017

Australian Researchers Unveil First Complete Silicon Quantum ComputerProcessor

Australian Researchers Unveil First Complete Silicon Quantum Computer Processor

16 DEC 2017

A reimagining of today’s computer chips by UNSW engineers shows how a quantum computer can be manufactured – using mostly standard silicon technology.

A reimagining of today’s computer chips by Australian and Dutch engineers shows how a quantum computer can be manufactured – using mostly standard silicon technology.

Australian Researchers Unveil First Complete Silicon Quantum Computer Processor
Australian Researchers Unveil First Complete Silicon Quantum Computer Processor

Research teams all over the world are exploring different ways to design a working computing chip that can integrate quantum interactions. Now, UNSW engineers believe they have cracked the problem, reimagining the silicon microprocessors we know to create a complete design for a quantum computer chip that can be manufactured using mostly standard industry processes and components.

The new chip design, published in the journal Nature Communications, details a novel architecture that allows quantum calculations to be performed using existing semiconductor components, known as CMOS (complementary metal-oxide-semiconductor) – the basis for all modern chips.

It was devised by Andrew Dzurak, director of the Australian National Fabrication Facility at the University of New South Wales (UNSW), and Menno Veldhorst, lead author of the paper who was a research fellow at UNSW when the conceptual work was done.

“We often think of landing on the Moon as humanity’s greatest technological marvel,” said Dzurak, who is also a Program Leader at Australia’s famed Centre of Excellence for Quantum Computation and Communication Technology (CQC2T). “But creating a microprocessor chip with a billion operating devices integrated together to work like a symphony – that you can carry in your pocket! – is an astounding technical achievement, and one that’s revolutionised modern life.

“With quantum computing, we are on the verge of another technological leap that could be as deep and transformative. But a complete engineering design to realise this on a single chip has been elusive. I think what we have developed at UNSW now makes that possible. And most importantly, it can be made in a modern semiconductor manufacturing plant,” he added.

Veldhorst, now a team leader in quantum technology at QuTech – a collaboration between Delft University of Technology and TNO, the Netherlands Organisation for Applied Scientific Research – said the power of the new design is that, for the first time, it charts a conceivable engineering pathway toward creating millions of quantum bits, or qubits.

“Remarkable as they are, today’s computer chips cannot harness the quantum effects needed to solve the really important problems that quantum computers will. To solve problems that address major global challenges – like climate change or complex diseases like cancer – it’s generally accepted we will need millions of qubits working in tandem. To do that, we will need to pack qubits together and integrate them, like we do with modern microprocessor chips. That’s what this new design aims to achieve.

“Our design incorporates conventional silicon transistor switches to ‘turn on’ operations between qubits in a vast two-dimensional array, using a grid-based ‘word’ and ‘bit’ select protocol similar to that used to select bits in a conventional computer memory chip,” he added. “By selecting electrodes above a qubit, we can control a qubit’s spin, which stores the quantum binary code of a 0 or 1. And by selecting electrodes between the qubits, two-qubit logic interactions, or calculations, can be performed between qubits.”

A quantum computer exponentially expands the vocabulary of binary code used in modern computers by using two spooky principles of quantum physics – namely, ‘entanglement’ and ‘superposition’. Qubits can store a 0, a 1, or an arbitrary combination of 0 and 1 at the same time. And just as a quantum computer can store multiple values at once, so it can process them simultaneously, doing multiple operations at once.

This would allow a universal quantum computer to be millions of times faster than any conventional computer when solving a range of important problems.

There are at least five major quantum computing approaches being explored worldwide: silicon spin qubits, ion traps, superconducting loops, diamond vacancies and topological qubits; UNSW’s design is based on silicon spin qubits. The main problem with all of these approaches is that there is no clear pathway to scaling the number of quantum bits up to the millions needed without the computer becoming huge a system requiring bulky supporting equipment and costly infrastructure.

That’s why UNSW’s new design is so exciting: relying on its silicon spin qubit approach – which already mimics much of the solid-state devices in silicon that are the heart of the US$380 billion global semiconductor industry – it shows how to dovetail spin qubit error correcting code into existing chip designs, enabling true universal quantum computation.

Unlike almost every other major group elsewhere, CQC2T’s quantum computing effort is obsessively focused on creating solid-state devices in silicon, from which all of the world’s computer chips are made. And they’re not just creating ornate designs to show off how many qubits can be packed together, but aiming to build qubits that could one day be easily fabricated – and scaled up.

“It’s kind of swept under the carpet a bit, but for large-scale quantum computing, we are going to need millions of qubits,” said Dzurak. “Here, we show a way that spin qubits can be scaled up massively. And that’s the key.”

The design is a leap forward in silicon spin qubits; it was only two years ago, in a paper in Nature, that Dzurak and Veldhorst showed, for the first time, how quantum logic calculations could be done in a real silicon device, with the creation of a two-qubit logic gate – the central building block of a quantum computer.

“Those were the first baby steps, the first demonstrations of how to turn this radical quantum computing concept into a practical device using components that underpin all modern computing,” said Mark Hoffman, UNSW’s Dean of Engineering. “Our team now has a blueprint for scaling that up dramatically.

“We’ve been testing elements of this design in the lab, with very positive results. We just need to keep building on that – which is still a hell of a challenge, but the groundwork is there, and it’s very encouraging. It will still take great engineering to bring quantum computing to commercial reality, but clearly the work we see from this extraordinary team at CQC2T puts Australia in the driver’s seat,” he added.

Other CQC2T researchers involved in the design published in the Nature Communications paper were Henry Yang and Gertjan Eenink, the latter of whom has since joined Veldhorst at QuTech.

The UNSW team has struck a A$83 million deal between UNSW, Telstra, Commonwealth Bank and the Australian and New South Wales governments to develop, by 2022, a 10-qubit prototype silicon quantum integrated circuit – the first step in building the world’s first quantum computer in silicon.

In August, the partners launched Silicon Quantum Computing Pty Ltd, Australia’s first quantum computing company, to advance the development and commercialisation of the team’s unique technologies. The NSW Government pledged A$8.7 million, UNSW A$25 million, the Commonwealth Bank A$14 million, Telstra A$10 million and the Australian Government A$25 million.

Source : Complete Design of a Silicon Quantum Qomputer Chip Unveiled


  • STILLS: Pictures of Dzurak and Veldhorst, plus illustrations of the complete quantum computer chip. (Photos: Grant Turner/UNSW, Illustrations: Tony Melov/UNSW)

  • BACKGROUNDERS: How UNSW’s ‘silicon spin qubit’ design compares with other approaches; plus a free 3,000-word feature article on the UNSW effort (Creative Commons).

  • SCIENTIFIC PAPER: Original paper in Nature Communications, “Silicon CMOS architecture for a spin-based quantum computer”.

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