Researchers at Princeton University have made an exciting discovery in the world of quantum physics.
They found a hidden “chiral” quantum state in a material called KV₃Sb₅, which was previously thought to be non-chiral.
Chirality, sometimes called “handedness,” describes objects that are different from their mirror images—like your left and right hands.
This property is common in nature, from DNA’s double-helix to the spiral of a snail shell.
Finding it in a quantum material like KV₃Sb₅ is a major breakthrough that could lead to new technologies.
The discovery was made by a team led by Professor M. Zahid Hasan, using a special tool called a scanning photocurrent microscope (SPCM). This new device allowed the researchers to detect subtle differences in the material’s behavior when exposed to light.
Their findings, published in Nature Communications, revealed that KV₃Sb₅ can form a unique pattern called a “charge density wave,” which is like a ripple of electric charge moving through the material. Under certain conditions, this wave creates a chiral state that breaks its usual symmetrical structure.
KV₃Sb₅ is made up of a special arrangement of atoms called a Kagome lattice, named after a Japanese bamboo weaving pattern. For a long time, scientists believed that this lattice was completely symmetrical, with no left or right “handedness.”
However, in 2021, Hasan’s team noticed strange behavior in the material when cooled to very low temperatures. This sparked curiosity, leading them to investigate further with the SPCM.
The SPCM allowed them to shine circularly polarized light—light that spirals in a particular direction—onto the material. They then measured how the material responded.
Surprisingly, when the light was right-handed, the material produced a different electric current than when the light was left-handed.
This change, called the “circular photogalvanic effect,” was a clear sign that the material was behaving chirally, something scientists had never observed in a topological quantum material before.
To confirm their findings, the researchers created super-clean quantum crystals of KV₃Sb₅ and cooled them to just 4 degrees Kelvin—almost as cold as outer space.
At this temperature, the material’s chiral behavior became obvious, proving that its symmetry had indeed been broken. Graduate student Zi-Jia Cheng and postdoctoral researcher Shafayat Hossain, who co-led the study, were thrilled with the discovery, as it finally settled a long-standing debate in physics about whether such materials could spontaneously develop chirality.
Despite this success, the researchers admit they don’t yet fully understand why this happens. “We confirmed the phenomenon, but we still don’t have a complete theory as to why it occurs,” Hasan said.
He and his team are eager to explore this mystery further, believing it could lead to groundbreaking advancements in optoelectronics and even solar technology.
Hasan compares their discovery to pointing the James Webb Space Telescope at the quantum world and finding something completely unexpected.
He believes this is just the beginning of a new chapter in quantum physics, with much more to discover about the hidden properties of these exotic materials.
With their newly developed tools, the team hopes to uncover even more secrets lurking in the quantum realm.
Source: Princeton University.
