Researchers at the University of Münster and Forschungszentrum Jülich demonstrated what is known as energy quantization in nanowires made of high-temperature superconductors (superconductors in which the temperature is elevated below which quantum mechanical effects predominate). The superconducting nanowire then assumes only selected energy states that could be used to encode information. In the high-temperature superconductors, the researchers were also able to observe for the first time the absorption of a single photon, a light particle that serves to transmit information.
The scientists used superconductors made of the elements yttrium, barium, copper oxide and oxygen, YBa2Cu3O7–x, or YBCO for short, from which they fabricated a few nanometer thin wires. When these structures conduct, electrical current physical dynamics called phase slips occur.
In the case of YBCO nanowires fluctuations of the charge carrier density cause variations in the supercurrent. The researchers investigated the processes in the nanowires at temperatures below 20 Kelvin, which corresponds to minus 253 degrees Celsius. In combination with model calculations, they demonstrated a quantization of energy states in the nanowires.
The temperature at which the wires entered the quantum state was found at 12 to 13 Kelvin — a temperature several hundred times higher than the temperature required for the materials normally used. This enabled the scientists to produce resonators with much longer lifetimes and to maintain the quantum mechanical states for longer. This is a prerequisite for the long-term development of ever larger quantum computers.
The study has been published in the journal Nature Communications. (WWU Münster)