Published 19-12-2017


Silicon spin qubits

Engineers at UNSW reckon they have cracked one of the key barriers to quantum computing, by creating a novel chip design using industry-standard CMOS technology. The new chip design is potentially the engineering pathway toward creating the millions of quantum bits, or qubits, required for quantum computing

The design has been published in the journal Nature Communications by Andrew Dzurak, Director of the Australian National Fabrication Facility at UNSW, and Menno Veldhorst, lead author of the paper who was a research fellow at UNSW when the conceptual work was done.

Dzurak is also a Program Leader at Australia’s famed Centre of Excellence for Quantum Computation and Communication Technology (CQC2T).

Veldhorst is 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.

Says Veldhorst: “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. 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.”

There are at least five major quantum computing approaches being explored worldwide: silicon spin qubits, ion traps, superconducting loops, diamond vacancies and topological qubits. The UNSW design is based on silicon spin qubits.

Unlike almost every other major group elsewhere, CQC2T’s quantum computing effort is obsessively focused on creating solid-state devices in silicon. 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 UNSW team has set up a AU$83 million deal with Telstra, Commonwealth Bank and the Australian and NSW governments to develop a 10-qubit prototype silicon quantum integrated circuit by 2022. And last August, the partners launched Silicon Quantum Computing, Australia’s first quantum computing company, to advance the development and commercialisation of the team’s unique technologies.


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