A team of quantum computer physicists at UNSW Sydney have engineered a quantum processor at the atomic scale to simulate the behavior of a small organic molecule, solving a challenge set some 60 years ago by theoretical physicist Richard Feynman.
The achievement, which occurred two years ahead of schedule, represents a major milestone in the race to build the world’s first quantum computer and demonstrates the team’s ability to control the quantum states of electrons and atoms in silicon at an exquisite level not achieved before.
Lead researcher and former Australian of the Year, Scientia Professor Michelle Simmons, said the team at Silicon Quantum Computing, one of UNSW’s most exciting start-ups, built a quantum integrated circuit comprising a chain of 10 quantum dots to simulate the precise location of atoms in the polyacetylene chain.
“And so that’s what we’re doing, we’re building it from the bottom up, where we are mimicking the polyacetylene molecule by putting atoms in silicon with the exact distances that represent the single and double carbon-carbon bonds.”
The research relied on measuring the electric current through a deliberately engineered 10-quantum dot replica of the polyacetylene molecule as each new electron passed from the source outlet of the device to the drain – the other end of the circuit. The current that passes through each chain was therefore dramatically different due to the different bond lengths of the atoms at the end of the chain.
“Most of the other quantum computing architectures out there can’t engineer atoms with sub-nanometer precision or allow the atoms to sit that close. Simmons, it was no accident that a carbon chain of 10 atoms was chosen because that sits within the size limit of what a classical computer can compute, with up to 1024 separate interactions of electrons in that system.
Future quantum computers
Much has been written about quantum computers in the last three decades with the billion-dollar question always being ‘but when can we see one?’. Simmons says that the development of quantum computers is on a comparable trajectory to how classical computers evolved – from a transistor in 1947 to an integrated circuit in 1958, and then small computing chips that went into commercial products like calculators approximately five years after that. And this latest result, realized in 2021 is the equivalent of the atom-scale quantum integrated circuit, two years ahead of time. If we map it to the evolution of classical computing, we’re predicting we should have some kind of commercial outcome from our technology five years from now.”
One of the advantages that the UNSW/SQC team’s research brings is that the technology is scalable because it manages to use fewer components in the circuit to control the qubits – the basic bits of quantum information.
“In quantum systems, you need something that creates the qubits, some kind of structure in the device that allows you to form the quantum state,” Prof. Whereas most quantum computing architectures need almost double the number or more of the control systems to move the electrons in the qubit architecture.”
Needing fewer components packed in tightly together minimizes the amount of any interference with the quantum states, allowing devices to be scaled up to make more complex and powerful quantum systems. That’s why it’s valuable for scalable quantum computing.”
John Ravenporton is a writer for many popular online publications. John is now our chief editor at DailyTechFeed. John specializes in Crypto, Software, Computer and Tech related articles.