In a first, a team of Australian and Dutch engineers has created a complete design for a quantum computer chip that can be manufactured using mostly standard silicon technology.
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.
“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,” said Andrew Dzurak, Director of the Australian National Fabrication Facility at the University of New South Wales (UNSW).
“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,” Dzurak said.
“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.
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, said study lead author Menno Veldhorst of QuTech, a collaboration between Delft University of Technology and TNO, the Netherlands Organisation for Applied Scientific Research.
The researchers explained that today’s computer chips, although remarkable, cannot harness the quantum effects needed to solve many important problems.
To solve problems that address major global challenges — like climate change or complex diseases like cancer — it is generally accepted we will need millions of quantum bits 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,” Veldhorst said.
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.
“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,” Veldhorst said.
“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,” he added.