In a laboratory at the University of California, Los Angeles, an ordinary amino acid unexpectedly helped a quantum material retain a special ordered behavior of electrons at a temperature previously considered unattainable. The material in question is tantalum disulfide — a material made of ultrathin layers only three atoms thick. At extreme cold, a so-called commensurate charge density wave arises in it: electrons move not chaotically but in a coordinated way, repeating the pattern of the crystal lattice.
Normally, this quantum state disappears as soon as the temperature rises above minus 57 °C. Thermal vibrations of atoms quickly destroy the fragile order. A team led by Xiangfeng Duan added molecules of arginine — one of the twenty standard amino acids from which proteins are built — to the tantalum disulfide layers. The result was astonishing: the ordered motion of electrons persisted all the way up to plus 57 °C.
Arginine fit the crystal lattice of tantalum disulfide like a perfect puzzle piece. Its size and charge distribution matched precisely the gaps between the layers of the material. Two other amino acids tested did not produce such an effect. Computer calculations confirmed that it is precisely this geometric and electronic “match” that stabilizes the quantum state at room and even elevated temperature.
The discovery matters not only for fundamental science. The ordered motion of electrons in such materials can be used to create a new type of energy-saving memory, in which information is stored not in ordinary charge but in quantum properties. For now this is only a prospect, but the method — using molecules of life to tune inorganic crystals — opens a new path in the design of quantum materials.
The researchers plan to test other molecules and to find out whether superconductivity or other quantum effects can be stabilized in the same way. If the approach works, then instead of searching for new exotic compounds, scientists will be able to select already known organic “keys” for the needed inorganic “locks.”
A simple amino acid that was previously associated only with biology is now helping quantum physics move beyond the confines of cryogenic laboratories.
