| The quantum entanglement is one of the important resources in quantum information and quantum computation. In this paper, the influences of the nearest-neighbor coupling and external magnetic field on the entanglement resonance and entanglement dynamics in Heisenberg spin chains are investigated.Firstly, the entanglement resonance in anisotropic spin-1/2 Heisenberg chains of different couplings is investigated when the nearest neighbor coupling is periodically modulated with a constant external magnetic field. When the modulation frequency equals twice of the magnetic field, the peak in entanglement appears. This peak is higher than peaks at other modulation frequencies. The entanglement resonance occurs. The height of the peak decreases as the number of spins in the chain increases. When the modulation frequency equals the magnetic field, the second peak of entanglement resonance appears. The height of the second peak can be reduced to a quite low value by varying the nearest neighbor coupling along z axis.Secondly, the entanglement dynamics between two end spins in an anisotropic spin-1/2 Heisenberg chain is investigated when the external magnetic field and the nearest-neighbor coupling are periodically modulated. The entanglement resonance occurs at certain modulation frequencies. At particular modulation frequency, the maximum entanglement can keep for a broad range of the magnitude of external magnetic field. It can suddenly drop to a very low value and even zero at certain magnitudes and then jump to the maximum value again. Thus, the entanglement can be controlled by varying the modulation frequency and the magnitude of external magnetic field. |
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