The mechanical compression enhancement of electronic degeneracy in superconducting hydrides

As one of the fundamental phenomena in quantum mechanics, quantum degeneracy is a specific regime in which collective and coherent phenomena dominate. The Cooper pair of a metal superconductor is an example of quantum degeneracy. Therefore, it is imperative to understand the dynamic formation and breaking process of quantum degeneracy of high-temperature superconductors relevant to spatial dimension and symmetry constraints. We developed an accurate non-perturbation electron-phonon interaction simulation and applied it to study the dynamic process of removing electronic degeneracy in superconducting hydrides under mechanical compression. The simulation shows that the degenerate electronic energy levels near the Fermi surface may hold more electrons or holes to form Cooper pairs. However, the direct electron-phonon interactions related to specific vibrational motion can remove electronic degeneracy, breaking Cooper pairs even at absolute zero temperature. The specific vibrational motion to stretch chemical bonds can interact with Cooper pairs, spontaneously and dynamically removing all degeneracies. Combined with spatial dimension and symmetry constraints, mechanical compression can enhance the electronic degeneracy to keep Cooper pairs in superconducting hydrides. As a result, such simulations may apply to search for stable high-temperature superconducting hydrides at lower pressures.