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Quest for room temperature superconductivity

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This is a topic which I’ve followed for decades. A holy grail of physics: room temperature superconductivity. The physics of Cooper pairs: what makes two electrons pair up when their charge actually makes them repel each other?

SciTechDaily > “Breakthrough in Understanding the Physics of High-Temperature Superconductivity” by Helmholtz-Zentrum Dresden-Rossendorf (May 12, 2020).

How do electrons form pairs in high-temperature superconductors such as cuprates?

In superconductivity, electrons combine to create “Cooper pairs,” which enables them to move through the material in pairs without any interaction with their environment. But what makes two electrons pair up when their charge actually makes them repel each other?

For conventional superconductors, there is a physical explanation: … One electron distorts the crystal lattice, which then attracts the second electron. For cuprates, however, it has so far been unclear which mechanism acts in the place of lattice vibrations.

At this point “Higgs oscillations” enter the stage: In high-energy physics, they explain why elementary particles have mass. But they also occur in superconductors, where they can be excited by strong laser pulses. They represent the oscillations of the order parameter – the measure of a material’s superconductive state, in other words, the density of the Cooper pairs.

So, “Higgs oscillations” = oscillations in the density of the Cooper pairs? Such oscillation can be induced via cyclic high-energy laser pulses. Like using your legs to continuously maintain a swing, eh.

[Image caption] By applying a strong terahertz pulse (frequency ω), they stimulated and continuously maintained Higgs oscillations in the material (2ω). Driving the system resonant to the Eigenfrequency of the Higgs oscillations in turn leads to the generation of characteristic terahertz light with tripled frequency (3ω). Credit: HZDR / Juniks