INSTANTON AHARONOV-BOHM EFFECT AND MACROSCOPIC QUANTUM COHERENCE IN CHARGE-DENSITY-WAVE SYSTEMS

It is predicted that in a charge-density-wave (CDW) ring-shaped conductor, placed in an external vector-potential field, there should appear a new Aharonov-Bohm contribution to the magnetic susceptibility and the electrical conductivity oscillating as a function of the flux with the period |0=hc/2e. This contribution arises from instanton transitions between degenerate vacua of the CDW condensate and is the solid-state realization of vacuum in quantum field theory. The period transforms into |0/N in N strongly correlated parallel CDW chains. © 1990 The American Physical Society.