Witnessing Macroscopic Entanglement in a Staggered Magnetic Field

Abstract

We investigate macroscopic entanglement in an infinite XX spin-1/2 chain with staggered magnetic field, B_l=B+e^{-iπl}b. Using single-site entropy and by constructing an entanglement witness, we search for the existence of entanglement when the system is at absolute zero, as well as in thermal equilibrium. Although the role of the alternating magnetic field b is, in general, to suppress entanglement as do B and T, we find that when T=0, introducing b allows the existence of entanglement even when the uniform magnetic field B is arbitrarily large. We find that the region and the amount of entanglement in the spin chain can be enhanced by a staggered magnetic field.

arXiv commentAccepted for publication in Physical Review A, minor changes from previous version. 5 pages, 3 figures

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• Entanglement and magnetic order
• Entanglement propagation through spin chains in the presence of a staggered magnetic field
• Quantum phase transition by employing trace distance along with the density matrix renormalization group
• Entanglement and the Interplay between Staggered Fields and Couplings
• Quantum information processing at the cellular level. Euclidean approach
• Chaotic spin-spin entanglement on a recursive lattice
• When Do Superfluidity and Long Range Order Imply Entanglement?