Generalized Bloch theorem and chiral transport phenomena

TL;DR

This paper extends the Bloch theorem to a broad class of systems, revealing that chiral magnetic effects are akin to nonequilibrium steady states, while persistent axial currents are allowed, impacting understanding of quantum time crystals.

Contribution

It generalizes the Bloch theorem to systems with gauged particle number symmetry and explores implications for chiral transport phenomena and quantum time crystals.

Findings

Chiral magnetic effect as a nonequilibrium steady state

Persistent axial currents are not forbidden by the generalized Bloch theorem

Application to quantum time crystals

Abstract

Bloch theorem states the impossibility of persistent electric currents in the ground state of nonrelativistic fermion systems. We extend this theorem to generic systems based on the gauged particle number symmetry and study its consequences on the example of chiral transport phenomena. We show that the chiral magnetic effect can be understood as a generalization of the Bloch theorem to a nonequilibrium steady state, similarly to the integer quantum Hall effect. On the other hand, persistent axial currents are not prohibited by the Bloch theorem and they can be regarded as Pauli paramagnetism of relativistic matter. An application of the generalized Bloch theorem to quantum time crystals is also discussed.