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NUS quantum scientists achieve state-of-the-art defect-free atom array

Researchers from the Centre for Quantum Technologies (CQT) at the National University of Singapore have developed a novel method to pristinely arrange rubidium atoms into arrays about as wide as a human hair with the use of optical tweezers. Using their automated setup powered by a novel algorithm, the team led by Assistant Professor Loh Huanqian, Principal Investigator at CQT, realised a defect-free 225-atom array with a success probability of 33 per cent. This is among the highest success probabilities reported in the literature for room temperature setups.

Quantum arrays can help scientists to perform powerful quantum simulations of materials. Perfection in the pattern is important because defects, or missing atoms, in an array have been found to deteriorate the observed signal in quantum simulations.

The CQT group achieved this by rearranging multiple atoms with several optical tweezers, making it more efficient and flawless than existing methods that only move one atom at a time using a single optical tweezer.

According to Mr Tian Weikun, the first author of the research paper and a doctoral student at CQT, rearranging atoms one at a time is like typing with only one finger. He commented, “Our novel approach rearranges multiple atoms at a time. It is akin to typing with multiple fingers, which is much faster and saves time.” In addition, atoms do not stay in position forever. The faster the simulation rearranges the atoms, the lower the probability of incurring defects.

The researchers demonstrated their approach by using it to shape arbitrary geometries, such as the honeycomb, kagome, and link-kagome, which are useful in studying different advanced materials such as graphene, superconductors, or quantum spin liquids.

Asst Prof Loh said, “Just to show that we’ve done this in Singapore, we also arranged single atoms to form the Lion Head symbol.” The Lion Head symbol was introduced as a national symbol in 1986, and it symbolises courage, strength and excellence.”

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