Stir of Echoes? Google uses constructive interference in quantum advantage claim

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Google Quantum Echoes

Google said on Wednesday that its new approach to calculating out-of-time-order correlators is capable of 13,000 times better performance than classical systems. Calling the algorithm Quantum Echoes, the company published findings that measured molecular geometries in NMR data.

“Our new technique works like a highly advanced echo. We send a carefully crafted signal into our quantum system (qubits on Willow chip), perturb one qubit, then precisely reverse the signal’s evolution to listen for the ‘echo’ that comes back,” Google’s Hartmut Neven and Vadim Smelyanskiy said in a blog post. 

“This quantum echo is special because it gets amplified by constructive interference — a phenomenon where quantum waves add up to become stronger. This makes our measurement incredibly sensitive.”

Details of the constructive interference approach were published in Nature. NMR findings were shared in a preprint. Nature also published a news story with other researchers’ responses to the announcement.

Barium titanate transducers

Materials scientists at Penn State used a strained thin film of barium titanate about 40 nanometers thick to convert signal-carrying electrons into signal-carrying photons. They achieved a rate at room temperature that is 10 times better than what is often achieved.

“To go from individual quantum computers to quantum networks spread over multiple computers, information needs to be converted into a kind of light that we’re already very good at sending long distances, such as the infrared light used for fiber optic internet,” said Albert Suceava, doctoral candidate on the project.

This work was published in Advanced Materials.

Atom localization

A team at MIT shared a new computational method that enables optical microscopes to pinpoint individual atoms with a resolution of 0.178 angstroms in any material with a known atomic pattern. This approach could help guide the design of quantum devices, which often require placing individual atoms precisely within a crystal, according to the team.

This work was published in Nature Communications.

Surface immobilized electrides

Researchers at Auburn University introduced a new class of electrides, materials in which electrons behave like anions and are localized within a crystal structure without being bound to a particular atom. The team’s robust and tunable “surface immobilized electrides” anchor solvated electron precursors to stable surfaces such as diamond and silicon carbide.

This work was published in ACS Materials Letters.

Quickbits

• Walks in Rotation Spaces Return Home when Doubled and Scaled (PRL)

• University of Colorado Cancer Center earns grant to use quantum computing to identify new colorectal cancer drugs

• Quantum-enhanced multiparameter sensing in a single mode (Science Advances)

Quantum Campus is edited by Bill Bell, a science writer and marketing consultant who has covered physics and high-performance computing for more than 25 years. Disclosure statement.