Bah, I messed up the Pascal-bar conversion in the text. Carbon nanotubes have S = 100 GPa = 1 Mbar. Too late to edit now. Thanks for catching this.

Thanks for these numbers! Can such pressures be attained by other means rather than permanent confinement? For example, the near wall pressure of a collapsing ultrasound bubble reaches about 100 MPa. Three orders of magnitude too little but can this technology be used to achieve much higher pressures? If so I wonder if maintaining an aggregate of material at high pressure (a high pressure foam as it were) would be sufficient to achieve bulk superconductivity.