Australian scientists have constructed the world’s first-ever quantum computer circuit — one that comprises all the fundamental components present on a conventional computer chip but at the quantum scale.
The monumental finding was nine years in the making.
“This is the most exciting finding of my career,” senior author and quantum physicist Michelle Simmons, creator of Silicon Quantum Computing and head of the Center of Excellence for Quantum Computation and Communication Technology at UNSW told.
Not only did Simmons and her colleagues develop what’s effectively a working quantum processor, but also successfully tested it by simulating a tiny molecule in which each atom has numerous quantum states – something a typical computer would fail to do.
This indicates we’re now a step closer to finally leveraging quantum computing capability to comprehend more about the world around us, even at the lowest scale.
“In the 1950s, Richard Feynman said we’re never going to comprehend how the world works – how nature works – unless we can really start to manufacture it at the same size,” Simmons told.
“If we can start to comprehend materials at that level, we can create things that have never been manufactured before.
“The question is: how can you genuinely govern nature at that level?”
The current breakthrough follows the team’s production of the first ever quantum transistor in 2012.
(A transistor is a tiny device that handles electronic signals and comprises just one element of a computer circuit. An integrated circuit is more complicated as it puts lots of transistors together.)
To accomplish this jump in quantum computing, the researchers employed a scanning tunnelling microscope in an ultra-high vacuum to arrange quantum dots with sub-nanometer accuracy.
The positioning of each quantum dot needs to be precisely perfect so the circuit could replicate how electrons hop along a string of single- and double-bonded carbons in a polyacetylene molecule.
The difficult portions were figuring out: precisely how many atoms of phosphorus should be in each quantum dot; exactly how far apart each dot should be; and then designing a machine that could position the tiny dots in exactly the proper order inside the silicon chip.
If the quantum dots are too huge, the interaction between two dots becomes “too enormous to separately regulate them”, the researchers explain.
If the dots are too tiny, then it creates randomness since each extra phosphorus atom may drastically vary the amount of energy it takes to add another electron to the dot.
The final quantum chip had 10 quantum dots, each made up of a tiny number of phosphorus atoms.
Double carbon bonds were mimicked by having less spacing between the quantum dots than single carbon bonds.
Polyacetylene was chosen since it’s a well-known model and could therefore be used to establish that the computer was accurately modelling the passage of electrons through the molecule.
Quantum computers are essential because traditional computers cannot represent huge molecules; they are just too complicated.
For example, to produce a simulation of the penicillin molecule with 41 atoms, a traditional computer would need 1086 transistors, which is “more transistors than there are atoms in the observable world”.
For a quantum computer, it would only require a processor of 286 qubits (quantum bits) (quantum bits).
Due to the fact that scientists presently have limited insight into how molecules behave at the atomic scale, the production of novel materials is fraught with uncertainty.
“Making a high-temperature superconductor has long been one of the holy grails,” explains Simmons. People just do not understand how it operates.
The study of artificial photosynthesis and how light is transformed to chemical energy through an organic chain of processes is another possible use of quantum computing.
The discovery of a more efficient catalyst for fertiliser production might save a substantial amount of money and energy.
Simmons asserts that the accomplishment of transitioning from quantum transistor to circuit in under nine years resembles the path established by the developers of traditional computers.
In 1947, the first traditional computer transistor was produced. In 1958, the first integrated circuit was constructed. These two ideas were separated by 11 years; Simmons’ team achieved this leap two years earlier than expected.