Topological superfluid 3He-B in magnetic field and Ising variable

Understand

The topological superfluid 3He-B provides many examples of the interplay of symmetry and topology.

• Here we consider the effect of magnetic field on topological properties of 3He-B.
• Magnetic field violates the time reversal symmetry.
• As a result, the topological invariant supported by this symmetry ceases to exist; and thus the gapless fermions on the surface of 3He-B are not protected any more by topology: they become fully gapped.