For the first time it is possible to design things that have never been manufactured
For the first time in the world, a quantum computer has been able to mimic nature at the atomic level using a chip that integrates all the components found on a classic computer chip, but at the atomic scale.
A team from the University of New South Wales (UNSW Sydney), led by Professor michelle simmonshas designed an atomic-scale quantum processor to simulate the behavior of a small organic molecule, thus solving a challenge posed some 60 years ago by theoretical physicist Richard Feynman.
Simmons recalls that, in the 1950s, Richard Feynman said that we will never understand how the world works, how nature works, unless we can begin to do so on the same scale. And he adds: “if we can begin to understand materials at that level, we can design things that have never been done & rdquor ;.
The achievement, which came two years ahead of schedule, represents a major milestone in the race to build the world’s first quantum computer, and demonstrates the possibility of controlling the quantum states of electrons and atoms in silicon at an exquisite level that it had not been achieved before, according to the researchers.
Embedded quantum processor
It is an integrated quantum processor to accurately model the quantum states of a small molecule of organic polyacetylenewhich will help create new materials.
The breakthrough will help industries build quantum models for a range of new products, such as pharmaceuticals, battery materials and catalysts, according to the Australian government.
Simmons and his team not only created what is essentially a working quantum processor, but also successfully tested it by modeling a small molecule in which each atom has multiple quantum states, something a traditional computer would struggle to achieve.
This suggests that we are one step closer to using quantum processing power to understand more about the world around us, even on the smallest scale.
Applied technology
He adds that, to make this leap in quantum computing, the researchers used a scanning tunneling microscope (used to image surfaces at the atomic level) in an ultra-high vacuum (which has a pressure of less than 10–7 mbar) to place quantum dots with sub-nanometer precision.
The location of each quantum dot had to be just right so that the circuit could mimic how electrons jump along a chain of single- and double-bonded carbons in a polyacetylene molecule.
The trickiest parts were figuring out: exactly how many phosphorus atoms should be in each quantum dot; exactly how far apart each point should be; and then design a machine that could place the tiny dots in exactly the right arrangement on the silicon chip.
The final quantum chip contained 10 quantum dots, each made up of a small number of phosphorus atoms. Carbon double bonds were simulated by putting less distance between quantum dots than carbon single bonds.
Polyacetylene was chosen because it is a well-known model and therefore could be used to show that the computer was correctly simulating the movement of electrons through the molecule.
historical milestone
Simmons also points out that the development of quantum computers is on a path comparable to the evolution of classical computers: from a transistor in 1947 to an integrated circuit in 1958, and then to small computer chips that became commercial products, such as calculators, approximately five years later. “Now we are replicating that roadmap for quantum computers & rdquor ;, he adds.
He explains that “we started with a single-atom transistor in 2012. And this latest result, made in 2021, is the equivalent of the atomic-scale quantum integrated circuit, two years ahead of time. If we compare it to the evolution of classical computing, we are predicting that we should have some kind of commercial outcome of our technology within five years.”
One of the advantages that this research brings is that the technology is scalable because it manages to use fewer components in the circuit to control the qubitswhich are 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,” says Professor Simmons.
Atoms that create qubits
“In our system, atoms themselves create qubits, which requires fewer elements in the circuits. We only needed six metal gates to control the electrons in our 10-point system; in other words, we have fewer gates than active components of the device”.
And it clearly marks the difference: “most quantum computing architectures need almost twice as many or more of the control systems to move the electrons in the qubit architecture & rdquor ;.
By requiring fewer tightly packed components, the amount of any interference with quantum states is minimized, allowing devices to be scaled up to create more complex and powerful quantum systems.
Looking ahead, Professor Simmons and her colleagues will explore larger compounds that may have been predicted theoretically, but have never been simulated or fully understood, such as high-temperature superconductors.
Reference
Engineering topological states in atom-based semiconductor quantum dots. M. Kiczynski et al. Nature, Volume 606, pages694–699 (2022). DOI:https://doi.org/10.1038/s41586-022-04706-0