Controlling entanglement spreading in unitary many-body dynamics by magnetic pulses.

The study of entanglement propagation in the dynamics of quantum multibody systems is an important problem in non-equilibrium physics. This paper optimizes the magnetic field to maximize the entanglement entropy and studies its influence on the entanglement propagation properties of quantum states. On the quantum Ising chain with the nearest neighbor coupling, the magnetic field obtained by variational optimization is applied to maximize the entanglement entropy of the final state and improve the entanglement growth rate in the ballistic transport region. At the same time, the entanglement entropy of the short chain can reach the entanglement saturation value of the long chain under a fixed magnetic field. When the chain length is increased, the saturation value of entanglement entropy increases, but the growth rate is almost the same. Specifically, by controlling the magnetic field, the entanglement growth rate of Heisenberg antiferromagnetic chain with only the nearest neighbor interaction can be increased to the same rate as that of the system with long-range interaction. The research in this paper reveals the ability of magnetic field to control entanglement propagation in non-equilibrium process, which can be applied to quantum control and information processing in the future. [ABSTRACT FROM AUTHOR]