A quantum spin liquid can form when atoms are placed in a trianglelike Kagome lattice.

Yet even without full-blown quantum computers, physicists are using related, more specialized types of machines — quantum simulators — to realize one of the initial aims of the field: to emulate the byzantine behavior of quantum systems. .

The new work uses a novel approach to quantum computing based on neutral atoms.

Although the method has lagged behind more popular quantum computing technologies such as superconducting circuits or trapped ions, neutral atoms have special properties that have long captured the imaginations of quantum engineers.

Next-generation machines have reached triple digits, making the would-be computers powerful simulators of quantum phenomena.  .

Researchers have been using these grids of neutral atoms to probe phases of quantum matter.

This summer, both the Cambridge and Paris groups simulated a textbook theory of magnetism — the quantum Ising model — for arrays of 256 and 196 atoms, respectively, and precisely measured how pockets of magnetism grow and shrink with changing temperature for the first time.

Now the Cambridge collaboration, comprised of Lukin’s team at Harvard, Greiner’s lab at Harvard, and Vladan Vuletić’s group at the Massachusetts Institute of Technology, has used their quantum simulator to probe a long-sought-after phase of matter. .

Punch a hole in an ice cube and it stays frozen, but remove the atoms at the center of a quantum spin liquid and the system’s properties could change

Various groups have seen indirect hints of quantum spin liquids, such as in the mineral Herbertsmithite, which has a crystal structure especially frustrating to atoms

The Cambridge group used the quantum simulator to get a bird’s-eye view

They first programmed their neutral atoms to act like the atoms in Herbertsmithite, with the on-off Rydberg state standing in for spin

Quantum simulators could prove useful for a number of practical problems, and both neutral atom groups have launched spinoff businesses: Pasqal for the Paris team, and QuEra Computing in Cambridge, which earlier this month announced that it raised $17 million from investors, including the Japanese communications and e-commerce giant Rakuten. 

Longer term, the companies hope to turn their simulators into universal quantum computers capable of handling any quantum calculation

While not as mature in this regard as the superconducting quantum computers from Google and IBM — which recently announced a 127-qubit universal quantum processor — neutral atoms may yet catch up