Engineers in Sydney have demonstrated a Atomic-scale quantum circuit made up of just a few atoms. By precisely controlling the quantum states of atoms, the new processor can simulate the structure and properties of molecules in a way that could unlock new materials and catalysts.
The new quantum circuit comes from researchers at the University of New South Wales (UNSW) and a startup called Silicon Quantum Computing (SQC). It is essentially made up of 10 carbon-based quantum dots embedded in silicon, with six metal gates that control the flow of electrons through the circuit.
It sounds simple enough, but the key lies in the arrangement of these carbon atoms down to the sub-nanometer scale. In relation to each other, they are precisely positioned to mimic the atomic structure of a particular molecule, allowing scientists to simulate and study that molecule’s structure and energy states more accurately than ever before.
In this case, they arranged the carbon atoms in the form of the organic compound polyacetylene, which is made up of a repeating chain of carbon and hydrogen atoms with an alternating pattern of single and double carbon bonds between them. To simulate those bonds, the team placed the carbon atoms at different distances.
The researchers then ran an electrical current through the circuit to see if it matched the signature of a natural polyacetylene molecule, and sure enough, it did. In further tests, the team created two different versions of the chain by cutting links in different places, and the resulting currents matched theoretical predictions perfectly.
The importance of this new quantum circuit, say the team, is that it could be used to study more complicated molecules, which could eventually produce new materials, pharmaceuticals or catalysts. This 10-atom version is right at the limit of what classical computers can simulate, so the team’s plans for a 20-atom quantum circuit would allow the simulation of more complex molecules for the first time.
“Most other quantum computing architectures out there don’t have the ability to design atoms with sub-nanometer precision or allow atoms to sit that close together,” said Professor Michelle Simmons, lead researcher on the study. “And that means we can now start to understand more and more complicated molecules based on putting the atoms in place as if they were mimicking the real physical system.”