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Scientists have directly observed angular momentum transfer through a crystal for the first time using terahertz laser pulses. They discovered that atomic rotations unexpectedly reverse direction during momentum transfer due to the crystal's underlying symmetry properties. This counterintuitive quantum effect demonstrates that two rotations can combine to produce a rotation in the opposite direction.
Why it matters
This discovery advances fundamental understanding of quantum mechanics and angular momentum behavior in materials. The findings could inform development of new quantum technologies and materials with precisely controllable magnetic or rotational properties.
Scientists have directly watched angular momentum move through a crystal for the very first time — and discovered a bizarre twist along the way. Using ultra-powerful terahertz laser pulses, researchers triggered tiny atomic rotations inside a quantum material and found that the direction of rotation can unexpectedly flip as momentum is transferred. The strange reversal happens because of the crystal’s underlying symmetry, creating an almost impossible-sounding effect where two rotations combine into one spinning the opposite way.
Source: Scientists discover atoms suddenly spinning backward in quantum experiment