Volume 3 Issue 8, August 2007
Superconductors, superfluids and supersolids can be defined in terms of how they respond to rotation. According to the London law, a rotating superconductor will generate a magnetic field that depends on fundamental constants alone. And for superfluids composed of neutral particles, such as helium-4, rotation velocities above a certain threshold will result in the formation of vortices; the quantization of the superfluid velocity within a vortex is known as Onsager-Feynman quantization. Both of these laws would be broken by a two-component superconductor, propose Egor Babaev and Neil Ashcroft. They show that for liquid metallic hydrogen, in which Cooper pairs can be formed through electron pairing and proton pairing, the superfluid velocity quantization becomes fractional and the generated magnetic field no longer depends only on fundamental constants but on density as well.
Editorial
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