Theory of quantum entanglement and the structure of two-mode squeezed antiferromagnetic magnon vacuum

Abstract

Recent investigations of the quantum properties of an antiferromagnet in the spin wave approximation have identified the eigenstates as two-mode squeezed sublattice states. The uniform squeezed vacuum and one-magnon states were shown to display a massive sublattice entanglement. Here we expand this investigation and study the squeezing properties of all sublattice Fock states throughout the magnetic Brillouin zone. We derive the full statistics of the sublattice magnon number with wave number $\vec{k}$ in the ground state and show that magnons are created in pairs with opposite wavevectors, hence, resulting in entanglement of both modes. To quantify the degree of entanglement we apply the Duan-Giedke-Cirac-Zoller inequality and show that it can be violated for all modes. The degree of entanglement decrease towards the corners of the Brillouin zone. We relate the entanglement to measurable correlations of components of the Néel and the magnetization vectors, thus, allowing to experimentally test the quantum nature of the squeezed vacuum. The distinct $\vec{k}$-space structure of the probabilites shows that the squeezed vacuum has a nonuniform shape that is revealed through the $\vec{k}$-dependent correlators for the magnetization and the Néel vectors.

References in corpus (26)

• Electric Field Effect in Atomically Thin Carbon Films
• Atomically thin MoS2: A new direct-gap semiconductor
• Two Dimensional Atomic Crystals
• Van der Waals heterostructures
• 2D materials and van der Waals heterostructures
• Layer-dependent Ferromagnetism in a van der Waals Crystal down to the Monolayer Limit
• Discovery of intrinsic ferromagnetism in 2D van der Waals crystals
• Inseparability criterion for continuous variable systems
• Magnetic 2D materials and heterostructures
• Micrometer-scale ballistic transport in encapsulated graphene at room temperature
• Cross-sectional imaging of individual layers and buried interfaces of graphene-based heterostructures and superlattices
• Long distance transport of magnon spin information in a magnetic insulator at room temperature
• Electrical Detection of Spin Transport in Lateral Ferromagnet-Semiconductor Devices
• Electrically controlled long-distance spin transport through an antiferromagnetic insulator
• Super-Poissonian shot noise of squeezed-magnon mediated spin transport
• Magnon squeezing in an antiferromagnet: reducing the spin noise below the standard quantum limit
• Antiferromagnetic magnons as highly squeezed Fock states underlying quantum correlations
• Magnon-squeezing as a niche of quantum magnonics
• Noninteger-spin magnonic excitations in untextured magnets
• Spin pumping and shot noise in ferrimagnets: bridging ferro- and antiferromagnets
• Magnonic black holes
• Tuning entanglement by squeezing magnons in anisotropic magnets
• Laser-driven quantum magnonics and THz dynamics of the order parameter in antiferromagnets
• Rayleigh-Jeans condensation of pumped magnons in thin film ferromagnets
• Magnon-magnon entanglement and its detection in a microwave cavity
• Magnon-mediated spin current noise in ferromagnet$|$non-magnetic conductor hybrids

Cited by in corpus (6)

• Quantum magnonics: when magnon spintronics meets quantum information science
• Master equation approach to magnon relaxation and dephasing
• Pure dephasing of magnonic quantum states
• Selection rules for ultrafast laser excitation and detection of spin correlations dynamics in a cubic antiferromagnet
• Thermal squeezing and nonlinear spectral shift of magnons in antiferromagnetic insulators
• Tunable phonon-driven magnon-magnon entanglement at room temperature