POSTECH researchers have developed a platform. It can control the properties of solid materials with light and measure them.
Scientists recognised for developing a platform to control and measure the properties of materials in various ways with light. The study was published in the journal Nature.
The electrical properties of a material are determined by the movement of electrons in the material. A material is defined as a metal if electrons can move freely. Otherwise, it is an insulator. Applying heat or pressure or adding impurities have been generally used, in order to change the electrical properties of these solids. This is because the change in the position of the atoms in the solid changes the movement of electrons accordingly.
The Floquet state has been proposed. Quantum states of matter can be easily manipulated with light, by adopting such a concept. It can be effectively used in quantum systems.
The light intensity for realizing Floquet state in solids was enormous due to the high frequency of light. Floquet states last only for a very short time of 250 femtoseconds. More quantitative studies of their characteristics have been limited, due to their transient nature.
The POSTECH scientists succeeded in the experimental realization of the steady Floquet state in a graphene Josephson junction (GJJ) and by irradiating continuous microwaves on it. The intensity of the light has been decreased to one trillionth the value of previous experiments. It significantly reduced the heat generation and enabling continuously long-lasting Floquet states.
Scientists also developed a novel superconducting tunneling spectroscopy to measure the Floquet states with high energy resolution. This is necessary to quantitatively verify the characteristics of the Floquet state that varies depending on the intensity, frequency and polarization of light applied to the device.