Chirality is the property of an object that makes it different from its mirror image, like our left and right hands.
In chiral crystals, the arrangement of atoms gives them a specific “handedness,” which can influence their optical and electrical behaviors.
However, not all crystals are naturally chiral.
Some, like antiferro-chiral crystals, are made of equal parts left- and right-handed structures, canceling out any overall handedness. One such material is boron phosphate (BPO₄), which is typically non-chiral.
A team of researchers from Hamburg and Oxford, led by Andrea Cavalleri at the Max Planck Institute for the Structure and Dynamics of Matter, discovered a way to temporarily induce chirality in BPO₄ using pulses of terahertz light.
Their findings, published in Science, showcase a groundbreaking method to manipulate the properties of materials on extremely short time scales.
The process involves a mechanism called nonlinear phononics. By using terahertz light at a specific frequency, the researchers excited vibrations in the crystal lattice.
These vibrations caused the atoms to move in a way that created a chiral state, lasting for a few trillionths of a second (picoseconds). Remarkably, by rotating the light’s polarization, the team could choose whether the crystal became left-handed or right-handed.
“This discovery shows how we can dynamically control materials at the atomic level,” said Cavalleri. “It opens the door to exciting new applications.”
The ability to create chirality in non-chiral materials could lead to innovative technologies, such as ultrafast memory devices or advanced optoelectronic systems. By controlling the handedness of a material with light, scientists could develop new functionalities that were previously unimaginable.
This research highlights how light can be used to change the fundamental properties of matter, potentially shaping the future of high-speed, energy-efficient devices.
