Physicists Observe Strange Quantum Rotation Effect That Defies Intuition

Researchers directly tracked angular momentum moving through a crystal lattice using ultrafast terahertz laser pulses.

They found that atomic rotational motion can reverse direction during transfer while still conserving total angular momentum.

The flip is tied to the symmetry of the crystal lattice, including in bismuth selenide.

The result offers a direct experimental view of angular momentum in solids and may help explain magnetism and control quantum materials.