Advances in Quantum Computing

February 8th, 2021
Quantum computing involves the use of strange quantum phenomena to perform computation. Instead of using standard binary factors, quantum computers utilise superposition and entanglement to solve problems. While research into this new type of computing began in the 1980s, it has remained mostly theoretical except for some extremely basic examples. While IBM, Microsoft, Google, Intel, and numerous tech heavyweights continue to invest heavily in quantum computing, a machine that works in the real world is still many years away. ;

A number of different models are used for quantum computers, including the popular quantum circuit model, which is based on the qubit. Short for quantum bit, qubits are likely to be the building blocks of viable quantum computers. Qubits can be in a 1 or 0 state just like regular computers, but they can also exist in a superposition (simultaneous until resolved) of 1 and 0 states. Qubits are a funny and fragile lot, however, with the most viable ones demanding a superconducting system with temperatures 250 times colder than deep space to remain stable.

Recent work by Australian scientists has made qubits much easier to manipulate - opening the door for new computers with thousands of qubits instead of a few dozen. According to Professor David Reilly, "To realise the potential of quantum computing, machines will need to operate thousands if not millions of qubits... The world's biggest quantum computers currently operate with just 50 or so qubits... This small scale is partly because of limits to the physical architecture that control the qubits. Our new chip puts an end to those limits."

While qubits need to exist in an ultra-cold temperature, they still need to interface with a control chip operating at regular room temperature. This creates heat, with more qubits leading to more control wires and additional heat generation. The University of Sydney and Microsoft team solved this problem by inventing a control chip that operates at the same temperature as the qubits. They designed an integrated circuit that can withstand extreme cold while producing hardly any heat. This development reduces the need for input wires and dramatically increases the number of qubits available for computational tasks.

"We've lifted the barrier that was limiting qubit count to tens of qubits," said Professor Reilly, adding "Over the next few years, these types of chips will be the reason machines will be able to scale into the many thousands." Other scientists are in agreement, including Andrew White, director of the Centre of Engineered Quantum Systems at the University of Queensland: "Given there's a worldwide gold rush for quantum technology, with big players like Google, Amazon and IBM, what David and his team have done is built the first decent pick and shovel... This is going to be transformational in the next few years. If everyone [developing quantum computers] isn't using this chip, they will be using something inspired by it."