arXiv:1110.0353 · Physical Review B
General quantum fidelity susceptibilities for the J1 - J2 chain
Mischa Thesberg, Erik Schwartz Sørensen
Abstract
We study slightly generalized quantum fidelity susceptibilities where the differential change in the fidelity is measured with respect to a different term than the one used for driving the system toward a quantum phase transition. As a model system we use the spin-$1/2$ ${J}_{1}$-${J}_{2}$ antiferromagnetic Heisenberg chain. For this model, we study three fidelity susceptibilities, ${\ensuremath{\chi}}_{\ensuremath{\rho}}$, ${\ensuremath{\chi}}_{D}$, and ${\ensuremath{\chi}}_{\mathrm{AF}}$, which are related to the spin stiffness, the dimer order, and antiferromagnetic order, respectively. All these ground-state fidelity susceptibilities are sensitive to the phase diagram of the ${J}_{1}$-${J}_{2}$ model. We show that they all can accurately identify a quantum critical point in this model occurring at ${J}_{2}^{c}\ensuremath{\sim}0.241{J}_{1}$ between a gapless Heisenberg phase for ${J}_{2}<{J}_{2}^{c}$ and a dimerized phase for ${J}_{2}>{J}_{2}^{c}$. This phase transition, in the Berezinskii-Kosterlitz-Thouless universality class, is controlled by a marginal operator and is therefore particularly difficult to observe.