在Lipkin-Meshcov-Glick模型中的多体约化保真率

We analyze the critical properties of Lipkin-Meshcov-Glick model in terms of fidelity susceptibility through -body reduced density matrix which we regard as reduced fidelity susceptibility. By computing the -body reduced density matrix, we obtain numerically the singular properties of reduced fidelity susceptibility in the vicinity of quantum transition point as well as its scaling behavior. We also make comparative study of ground-state and reduced ground-state susceptibility. We show that the -body reduced fidelity susceptibility can also be used to characterize QPTs