Author: Andrew See

Quantum engineers from UNSW Sydney have removed a major obstacle that has stood in the way of quantum computers becoming a reality: they discovered a new technique they say will be capable of controlling millions of spin qubits – the basic units of information in a silicon quantum processor.

Published today in Science Advances, the team led by Dr Jarryd Pla, and Scientia Professor Andrew Dzurak have found what they consider ‘the missing jigsaw piece’ in the quantum computer architecture that should enable the control of
the millions of qubits needed for extraordinarily complex calculations.

Their work is featured on the ABC website  and UNSW Newsroom

Professor Andrew Dzurak’s team has had new results opening the path to a quantum data bus for silicon CMOS quantum processor chips published in Nature Communications yesterday. These show that electron spin qubits can be transported between quantum dots while maintaining their spin polarisation (to 99.97%) and spin coherence (to 99.4%) information. The experiments were performed by former postdoc Jun Yoneda and former PhD student Wister Huang, crucial theory was supported by Andre Saraiva and his PhD student Mengke Feng, and all devices were all fabricated at ANFF-NSW.

UNSW researcher Dr Udo Römer has been granted an ARC Discovery Early Career Researcher Award for the project “Nervous tissue stimulation using multi-junction silicon photodiodes”. He will use the ANFF-NSF facilities for thin film depositions and microfabrication of devices.

Professor Andrew Dzurak’s team has had their work on CMOS qubits recognised with a recent paper acceptance in Nature Communications.

The paper reports an experimental demonstration of a new type of two-qubit logic gate based on our SiMOS qubit technology which allows more complex multi-electron spin systems to act as qubits.

The technological implications of this work are quite significant, since previous demonstrations have largely relied on qubits based on single electron wavefunctions, which can be easily distorted in a real CMOS device.  By moving to qubits containing more electrons the devices become more robust, and therefore more easily constructed using CMOS manufacturing.

The experiments were performed by our recently graduated PhD student, Ross Leon.  Ross was supported in his experiments by Dr Henry Yang, and the detailed theoretical analysis behind this work was led by Dr Andre Saraiva.

All of the qubit devices used for this study were fabricated entirely at our ANFF-NSW facility at UNSW.