Are degenerate groundstates induced by spontaneous symmetry breakings in quantum phase transitions?

Abstract

Recently, emergent symmetry is one of fast-growing intriguing issues in many-body systems. Its roles and consequential physics have not been well understood in quantum phase transitions. Emergent symmetry of degenerate groundstates is discussed in possible connection to spontaneous symmetry breaking within the Landau theory. For a clear discussion, a quantum spin-$1/2$ plaquette chain system is shown to have rich emergent symmetry phenomena in its groundstates. A covering symmetry group over all emergent symmetries responsible for degenerate groundstates in the plaquette chain system is found to correspond to a largest common symmetry group of constituent Hamiltonians describing the plaquette system. Consequently, this result suggests that, as a guiding symmetry principle in quantum phase transitions, {\it degenerate groundstates are induced by a spontaneous breaking of symmetries belonging to a largest common symmetry group of continent Hamiltonians describing a given system but can have more symmetries than the largest common symmetry}.

18 pages,18 figures

References in corpus (6)

• Classical simulation of infinite-size quantum lattice systems in two spatial dimensions
• Spectroscopic observation of SU(N)-symmetric interactions in Sr orbital magnetism
• Ground state fidelity from tensor network representations
• Spontaneous Particle-Hole Symmetry Breaking in the $\nu =5/2$ Fractional Quantum Hall Effect
• Emergent Symmetry and Dimensional Reduction at a Quantum Critical Point
• Center symmetry and Hagedorn spectrum