Regensburg 2022 – scientific programme

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MA: Fachverband Magnetismus

MA 13: Magnonics 1

MA 13.7: Talk

Tuesday, September 6, 2022, 11:00–11:15, H43

Long-range quantum entanglement between two distant ferromagnets mediated by dipol-dipol interaction — •Dennis Wuhrer, Niklas Rohling, and Wolfgang Belzig — Universität Konstanz, D-78457 Konstanz, Germany

Recently the quantum states of an antiferromagnet in the spin wave approximation have been identified as two-mode squeezed sublattice-magnon states. The massive sublattice entanglement leads to a non-trivial structure of the two-mode squeezed vacuum in the magnetic Brillouin Zone.

Further the entanglement in synthetic antiferromagnets became of interest. It can be tuned by an applied magnetic field, but an extraction of squeezing parameters is difficult. In this talk we regard a system consisting of two distant 2D ferromagnets coupled via dipol-dipol interaction. The Bogoliubov transformation will be interpreted in terms of inter-/intra-layer squeezing and hybridisation parameters. Using the logarithmic negativity we derive an analytic formula to quantify the degree of entanglement for which we investigate the distance dependence due to the long-range interaction. Using the distance and an external field the entanglement can be manipulated from zero to large values and maintained over large distances. The prospect to transfer massive entanglement over large distances is discussed.