Dutch researchers develop chip design for silicon quantum computer
There are at least five major quantum computing approaches being explored worldwide: silicon spin quantum bits (qubits), ion traps, superconducting loops, diamond vacancies and topological qubits. The new approach uses silicon spin qubits with a dedicated error correction scheme to allow the architecture scale to millions of quibits and can be built on standard CMOS technology.
“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 quantum bits, or 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,” said Dr Menno Veldhorst, team leader in quantum technology at QuTech – a collaboration between Delft University of Technology and TNO, the Netherlands Organisation for Applied Scientific Research.
“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 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.”
Such a design needs error-correcting codes which employ multiple qubits to store a single piece of data.
“Our chip blueprint incorporates a new type of error-correcting code designed specifically for spin qubits, and involves a sophisticated protocol of operations across the millions of qubits. It’s the first attempt to integrate into a single chip all of the conventional silicon circuitry needed to control and read the millions of qubits needed for quantum computing,” said Andrew Dzurak, director of the Australian National Fabrication Facility at the University of New South Wales (UNSW) and Program Leader at Australia’s Centre of Excellence for Quantum Computation and Communication Technology (CQC2T).
“We expect that there will still be modifications required to this design as we move towards manufacture, but all of the key components that are needed for quantum computing are here in one chip. And that’s what will be needed if we are to make quantum computers a workhorse for calculations that are well beyond today’s computers,” he added. “It shows how to integrate the millions of qubits needed to realise the true promise of quantum computing.”
The UNSW team has struck a A$83m (£50m) deal between UNSW, Telstra, Commonwealth Bank and the Australian and New South Wales governments to develop a 10-qubit prototype silicon quantum integrated circuit. This is expected in 2022 from a spinout company called Silicon Quantum Computing.
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