Relation between pseudospin-rotation invariance and a supersolid

Abstract

In this paper, we discuss the physical meaning of pseudospin symmetry, which is actually a kind of particle-hole rotation invariance. In an isotropic state with the total pseudospin S\ifmmode \tilde{}\else \~{}\fi{}=0, by using the invariance of the pseudospin rotation in space, we shall establish a relation between off-diagonal long-range order (ODLRO) and charge-density waves (CDW). This result indicates that ODLRO and CDW must coexist in such an isotropic state, which is usually called a supersolid. Finally, we present two examples to show that a supersolid exists.