Researchers found that low-energy and high energy states are correlated in a layered, superconducting material LSCO (lanthanum, strontium, copper, oxygen).
Exciting the material with an ultrafast (<100fs) beam of near-infrared light produces coherent excitations lasting a surprisingly ‘long’ time of around 500 femtoseconds, originating from a quantum superposition of excited states within the crystal.
The strong correlation between the energy of this coherence and the optical energy of the emitted signal indicates a coherent interaction between the states at low and high energy.
This kind of coherent interaction, reported for the first time, is the root of many intriguing and poorly-understood phenomena displayed by quantum materials.
It is one of the first applications of multidimensional spectroscopy to study of correlated electron systems such as high-temperature superconductors.
The paper has been published in Science Advances. (ARC Centre of Excellence in Future Low-Energy Electronics Technologies)