paper

Long-range-ordered phase in a quantum Heisenberg chain with interactions beyond nearest neighbors

arXiv:2103.04271 · doi:10.1103/PhysRevA.104.013303

Abstract

Spin ensembles coupled to optical cavities provide a powerful platform for engineering synthetic quantum matter. Recently, we demonstrated that cavity mediated infinite range interactions can induce fast scrambling in a Heisenberg spin chain (Phys. Rev. Research {\bf 2}, 043399 (2020)). In this work, we analyze the kaleidoscope of quantum phases that emerge in this system from the interplay of these interactions. Employing both analytical spin-wave theory as well as numerical DMRG calculations, we find that there is a large parameter regime where the continuous symmetry of this model is spontaneously broken and the ground state of the system exhibits order. This kind of symmetry breaking and the consequent long range order is forbidden for short range interacting systems by the Mermin-Wagner theorem. Intriguingly, we find that the order can be induced by even an infinitesimally weak infinite range interaction. Furthermore, we demonstrate that in the symmetry broken phase, the half chain entanglement entropy violates the area law logarithmically. Finally, we discuss a proposal to verify our predictions in state-of-the-art quantum emulators.

arXiv comment7 pages, 2 Figures

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