Fidelity and criticality of a quantum Ising chain with long-range interactions

We study the criticality of a long-range quantum ferromagnetic Ising chain with algebraically decaying interactions 1 /r^α via the fidelity susceptibility based on the exact diagonalization and the density-matrix renormalization-group techniques. We find that critical exponents change monotonically from the mean-field universality class to the short-range Ising universality class for intermediate α , which are consistent with recent results obtained from renormalization-group techniques. In addition, we determine the critical values for 1.8 ≤α ≤3 from the finite-size scaling of the fidelity susceptibility. Our work provides very nice numerical data from the fidelity susceptibility for the quantum long-range ferromagnetic Ising chain.