The researchers confirmed this by designing experiments that removed angular momentum while preserving helicity. The sideways rotation still occurred, showing that helicity plays the key role.

This finding offers a deeper understanding of how light interacts with matter at extremely small scales. It also points to new ways of controlling nanoscale systems, with possible applications in light-driven nanomachines and advanced sensing technologies.

“This work represents a new measurement paradigm for nanoscale optomechanics,” says Tanaka. “Just as optical tweezers opened a new field in single-molecule biophysics, we hope this platform will unlock access to nanoscale mechanical phenomena that have so far remained beyond reach.”