Australian scientists have created the world’s first quantum computer circuit – a circuit that contains all the basic components of a classic computer chip, but on a quantum scale. The landmark discovery, published yesterday in the Nature journal, has been under preparation for nine years.
“This is the most exciting discovery of my career,” told senior author and quantum physicist Michelle Simmons, founder of Silicon Quantum Computing and director of the Center of Excellence for Quantum Computation and Communication Technology at UNSW.
Not only did Simmons and her team create what is essentially a functional quantum processor, they also successfully tested it by modeling a small molecule in which each atom has several quantum states – something that would be difficult for a traditional computer to achieve.
This suggests that now we are one step closer to finally using the power of quantum processing to better understand the world around us, even on the smallest scale.
“In the 1950s, Richard Feynman said we’re never going to understand how the world works – how nature works – unless we can actually start to make it at the same scale,” Simmons told. “If we can start to understand materials at that level, we can design things that have never been made before. The question is: how do you actually control nature at that level?”
To make a leap in the field of quantum computing, the researchers used a tunnel scanning microscope in ultra-high vacuum to place quantum dots with subnanometer accuracy. The location of each quantum dot must be correct so that the circuit can mimic how electrons move along a string of single- and double-bonded carbons in a polyacetylene molecule.
The hardest part was figuring out exactly how many phosphorus atoms there should be in each quantum dot, the exact distance between each dot, and then developing a machine that could place tiny dots in the exact order inside a silicon chip. Researchers say that if quantum dots are too large, the interaction between the two points becomes “too large to control them independently.”
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Polyacetylene was chosen because it is a well-known model, and therefore it can be used to prove that a computer correctly simulates the motion of electrons through a molecule.
Because scientists have a limited idea of how molecules function on an atomic scale, there are many assumptions when creating new materials. “One of the holy grails has always been making a high temperature superconductor,” says Simmons. “People just don’t know the mechanism for how it works.” Another potential application of quantum computing is the study of artificial photosynthesis and how light is converted to chemical energy by an organic chain of reactions.
Another big problem that quantum computers can solve is the creation of fertilizers. Triple nitrogen bonds are currently broken under high temperature and pressure in the presence of an iron catalyst to form a fixed nitrogen fertilizer. Finding another catalyst that can make fertilizers more efficient can save a lot of money and energy.
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