Quantum spin liquid observed in physics first

Researchers finally document never-seen-before state of matter.

After 50 years of hunting, physicists have finally observed a new state of matter known as a quantum spin liquid.

“It is a very special moment in the field,” says physicist Mikhail Lukin, co-director of the Harvard Quantum Initiative (HQI) and a senior author on the study in

Science. “You can really touch, poke and prod at this exotic state and manipulate it to understand its properties… It’s a new state of matter that people have never been able to observe.”

Quantum spin liquids were first theorised in 1973 and have been hotly sought-after because of their potential applications in quantum computing and hightemperature superconductivity.

Researchers led by Harvard University have finally experimentally documented this new state of matter.

They set out to find it using a programmable quantum simulator at the HQI lab. This is a special kind of quantum computer that can create shapes like squares, honeycombs or triangular lattices, which in turn can engineer various interactions between ultracold atoms. It allows researchers to reproduce physics on a quantum scale, study the complex processes that arise – and control them.

“You can move the atoms apart as far as you want, you can change the frequency of the laser light, you can really change the parameters of nature,” explains co-author Subir Sachdev, also from Harvard University. “Here, you can look at each atom and see what it’s doing.”

The team used this simulator to create a quantum spin liquid, the properties of which could be key to creating qubits for quantum computers that aren’t affected by noise or interference.