Entanglement generation and steering implementation in a double-cavity-magnon hybrid system.

We demonstrate a scheme for the generation of bipartite and tripartite entanglement, as well as he implementation of stable and controllable long-distance one-way and asymmetric two-way steering in a cavity-magnon hybrid system. This system consists of a magnon mode and two coupled microwave cavities. The first cavity is driven by a flux-driven Josephson parametric amplifier, which generates squeezed vacuum fields, and is coupled to the other cavity through optical tunneling interaction. The second cavity and magnon mode are coupled through magnetic dipole interaction. We find that under weak coupling between the two cavities, and strong coupling between the second cavity and magnon mode, remote controllable one-way steering and tripartite entanglement can be achieved. Our scheme may have potential applications in quantum information.

Entanglement enhancement and EPR steering based on a PT-symmetric-like cavity-opto-magnomechanical hybrid system.

We investigate the enhancement of entanglement and EPR steering in a parity-time(PT-) symmetric-like cavity-opto-magnomechanical system. The system consists of an optical cavity, a magnon mode in a ferromagnetic crystal, a phonon mode, and a microwave cavity. Our findings demonstrate that microwave-cavity gain significantly boosts distant quantum entanglement and greatly improves the robustness of bipartite entanglement against environment temperature. Additionally, we observe an enhancement of tripartite entanglement within the system and uncover the phenomenon of entanglement transfer. Notably, we also achieve one-way steering and two-way asymmetric steering in the system. This study offers insights into the integration of traditional optomechanics and cavity magnomechanics, presenting a novel approach to manipulate asymmetric quantum steering between two distant macroscopic objects. The implications of our research extend to the fields of quantum state preparation and quantum information.

Entanglement enhanced by Kerr nonlinearity in a cavity-optomagnonics system.

We present a method to enhance steady-state bipartite and tripartite entanglement in a cavity-optomagnonics system by utilizing the Kerr nonlinearity originating from the magnetocrystalline anisotropy. The system comprises two microwave cavities and a magnon and represents the collective motion of several spins in a macroscopic ferrimagnet. We prove that Kerr nonlinearity is reliable for the enhancement of entanglement and produces a small frequency shift in the optimal detuning. Our system is more robust against the environment-induced decoherence than traditional optomechanical systems. Finally, we briefly analyze the validity of the system and demonstrate its feasibility for detecting the generated entanglement.

Adiabatic Generation of N-quNit Singlet States with Cavity QED.

We present a theoretical scheme to generate N-quNit singlet states with N 3 via adiabatic passage. In this protocol, the system may be robust against both experimental parameter fluctuations and dissipations along dark states. In addition, during the whole procedure, quantum information is almost fully transferred between atomic ground states. It reduces the influence of dissipations such as atomic spontaneous emissions and cavity decays. Thus, the presented proposal may be feasible based on current technologies.