Quantum speed limit of the evolution of the qubits in a finite XY spin chain

Abstract

We study the quantum speed limit (QSL) time of qubits in a finite XY spin chain with the influence of external transvers magnetic field. When the magnetic field is first at a given value and then suddenly turns off, the evolution of the system occurs. It is a novel discovery for us that there is different mechanism for speed-up of the three kinds of qubits in the same spin chain. For the QSL time of single-site qubit, we find that the transverse magnetization is a potential influence factor for the evolution of single qubit. As for the nearest-neighbor qubits’ QSL time, it is found that the entanglement between two nearest spins is an important resource for speeding up the system evolution. Finally, we analyze the QSL time of next-nearest-neighbor qubits and show that when the effect of entanglement is limit, quenched magnetic field and anisotropy parameter show the effectiveness on accelerating quantum evolution.