Researchers at JILA and Harvard University have made a breakthrough in understanding the interactions between quantum spins using a technique called Floquet engineering. By manipulating ultracold potassium-rubidium molecules, they were able to tune the interactions and observe two-axis twisting dynamics, which could lead to enhanced quantum sensing in the future.
Quantum Dancers on Stage
Think about a band of dancers on waft, every with its own repertoire. Now imagine these dancers are quantum spins and the way they interact to represent the fundamental magnetic systems in the universe.
For decades, physicists had had the goal of setting up controlled systems in the lab that mimic those interactions. But now a technique known as Floquet engineering, developed by Jun Ye and his team at JILA and Harvard University, has allowed for control of the interactions of two such molecules—those made of potassium and rubidium—at ultracold temperatures while exploring novel quantum many-body systems.
The Two-Axis Twist
Another notable observation by the researchers was the development of two-axis twisting dynamics in their system. In this process, the spins are pushed and pulled in two directions, transforming into extremely entangled states.
Such a finding is especially appealing from the standpoint of quantum sensing and metrology. Generating spin-squeezed states, which reduce the uncertainty in one component while increasing it for another, allows the researchers to improve sensitivity of their atomic spectroscopy experiments.
Two-axis twisting was a concept that dates back to the early 1990s, yet it wasn’t realized anywhere until it happened twice within two JILA labs in 2024. James Thompson and his team provided another similar experimental evidence in a completely different way — using Cavity Quantum Electrodynamics (cQED) apart from Ye’s group.
Conclusion
Discoveries like the one by Jun Ye’s group from JILA and Harvard University take us closer to a comprehensive picture of how quantum spins interact. They were able to precisely tune the interactions of ultracold potassium-rubidium molecules and, in doing so, observe for the first time anywhere the elusive two-axis twisting dynamics with extraordinary clarity using Floquet-engineering techniques This finding reveals a new basis of magnetic materials and implies the potential for improving quantum sensing and precision measurement techniques.
