Symmetry-protected Bose-Einstein condensation of interacting hardcore bosons

Abstract

Abstract The large practical potential of exotic quantum states is often precluded by their notorious fragility against external perturbations or temperature. Here, we introduce a mechanism stabilizing a one-dimensional quantum many-body phase exploiting an emergent $${{\mathbb{Z}}}_{2}$$ Z 2 -symmetry based on a simple geometrical modification, i.e. a site that couples to all lattice sites. We illustrate this mechanism by constructing the solution of the full quantum many-body problem of hardcore bosons on a wheel geometry, which are known to form Bose-Einstein condensates. The robustness of the condensate against interactions is shown numerically by adding nearest-neighbor interactions, which typically destroy Bose-Einstein condensates. We discuss further applications such as geometrically inducing finite-momentum condensates. Since our solution strategy is based on a generic mapping, our findings are applicable in a broader context, in which a particular state should be protected, by introducing an additional center site.