A Note on Bloch theorem

Understand

Bloch theorem in ordinary quantum mechanics means the absence of the total electric current in equilibrium.

• In the present paper we analyze the possibility that this theorem remains valid within quantum field theory relevant for the description of both high energy physics and condensed matter physics phenomena.
• First of all, we prove that the total electric current in equilibrium is the topological invariant for the gapped fermions that are subject to periodical boundary conditions, i.e.
• it is robust to the smooth modification of such systems.