Australian scientists put the quantum world on a microchip

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An Australian startup has just modeled a molecule on a microchip and placed atoms in silicon with a precision of less than nanometers.

This ability to simulate molecules at the atomic scale – where matter is ruled by quantum mechanics – could improve our understanding of the quantum world and lead to the creation of incredible new materials, such as high temperature superconductors or super efficient solar panels

“We could start mimicking how nature behaves and then we could start making new kinds of materials and devices that the world has never seen before,” said Michelle Simmons, founder of Silicon Quantum Computing, the startup responsible for the microchip.

think small

A few million years after making our first stone tools, humans discovered that when we zoom in on matter, looking at the atoms and subatomic particles that make up it, they adhere to a different set of rules than those governing objects on a larger scale. . Scale.

These rules (“quantum mechanics”) can have their own useful applications — MRI scanners, solar cells and atomic clocks all benefit from quantum phenomena.

“We can start making new kinds of materials and devices that the world has never seen before.”

Michelle Simmons

But while it’s easy to lift a rock and extrapolate that it might be good to bash things, it’s not so easy to see or understand how matter behaves at the quantum scale — mainly because observation itself affects quantum systems.

We can use computer programs to simulate how some small molecules behave at the atomic or subatomic level, but that’s not a viable option for larger molecules: there are too many possible interactions between their particles.

“If we can start to understand materials on… [the quantum] level, we can design things that have never been made before,” Simmons told ScienceAlert† “The question is: how do you actually control nature at that level?”

The Quantum Simulator

The answer seems to be by modeling molecules on silicon chips.

For a recent studyThe SQC team successfully fabricated an atomic-scale microchip, creating 10 uniformly sized artificial atoms — known as “quantum dots” — and then using a scanning tunneling microscope to precisely position the dots in silicon.

The team modeled their chip after the structure of polyacetylene, a molecule made of carbon and hydrogen atoms linked by alternating single and double carbon bonds.

The quantum simulator. Credit: Silicon Quantum Computing

Once it was built, they could apply an electrical charge to one part of the chip (the “source”) and study how it moved along the chain of atoms to exit at another part (the “drain”).

“We literally build it from the bottom up, mimicking the polyacetylene molecule by placing atoms in silicon at the exact distances that represent the carbon-carbon single and double bonds,” said Simons.

Based on theoretical predictions, polyacetylene is hypothesized to behave differently depending on whether the chain of molecules begins and ends with carbon double bonds or single carbon bonds.

“What [this model is] to show is that you can literally mimic what actually happens in the real molecule.”

Michelle Simmons

To check if their modeling technique was correct, the researchers created one chip based on each version — and saw that the number of electrical spikes changed as the current flowed through each version.

“This confirms long-standing theoretical predictions and demonstrates our ability to accurately simulate the polyacetylene molecule,” said SQC.

The team also observed an electron existing in two places at once, an example of the quantum phenomenon superposition

“What [this model is] show that you can literally mimic what’s really happening in the real molecule, and that’s why it’s so exciting because the signatures of the two chains are very different,” Simmons said.

As expected, the different configurations produced two different electrical currents. Credit: Silicon Quantum Computing

What’s next?

The team chose a 10-point chain of the polyacetylene molecule to demonstrate its technology, because that’s something we can simulate with classical computers. Now they are looking to scale up.

“We’re almost at the limit of what classical computers can do, so it’s like stepping off the edge into the unknown,” Simmons said. “And here’s the exciting thing — we can now make bigger devices beyond what a classic computer can model.”

These future quantum models could be for materials leading to new batteries, drugs and more, Simmons predicts.

“It won’t be long before we can realize new materials that have never existed before,” she said.

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