Los Alamos uses D-Wave annealers to show magnetic reversal in antiferromagnets

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Researchers at Los Alamos National Laboratory have used D-Wave quantum annealers to simulate an unusual magnetic effect. Quantum Zeitgeist's Ivy Delaney reports on the work by Elijah Pelofske, Pratik Sathe, Cristiano Nisoli and Frank Barrows, published in an APS journal

The team simulated magnetic hysteresis in antiferromagnetic models. Hysteresis describes how a material's magnetisation lags behind changes in an applied field, a bit like memory. Antiferromagnets normally resist being magnetised, because neighbouring spins point in opposite directions

Despite that, the simulations showed full saturation and reversal of the hysteresis curve. The team also saw step like jumps similar to Barkhausen noise in real magnets, along with domains linked to quantum fluctuations. The ratio between the transverse field and the coupling strength turned out to be critical for reaching full polarisation

The runs used four quantum processors at about 15 millikelvin and gave consistent results. The largest one dimensional model used up to 4,905 qubits on an Advantage 4.1 system and 1,131 on an Advantage2 prototype. The researchers also studied frustrated lattices, where spins cannot all be satisfied at once

This follows the D-Wave topological insulator work we discussed, and adds to the case for annealers as physics simulators. The write up comes from a secondary source with its own accuracy disclaimer, so the paper itself is the best guide. Still, using quantum hardware to explore magnetism is a natural fit

Are quantum annealers becoming useful scientific instruments? And which materials problems would you most like to see simulated?

Quantum Annealers Show Full Magnetic Reversal In Antiferromagnetsquantumzeitgeist.com