Effects of the interplay between interaction and disorder in bipartite entanglement

Abstract

We use a disordered antiferromagnetic spin-1 / 2 chain with anisotropic exchange coupling to model an array of interacting qubits. All qubits have the same level spacing, except two, which are called the defects of the chain. The level spacings of the defects are equal and much larger than all the others. We investigate how the entanglement between the two defects depends on the anisotropy of the system. When the anisotropy coupling is much larger than the energy difference between a defect and an ordinary qubit, the two defects become strongly entangled. Small anisotropies, on the contrary, may decrease the entanglement, which is, in this case, also much affected by the number of excitations. The analysis is made for nearest-neighbor and next-nearestneighbor defects. The decrease in the entanglement for nearest neighbor defects is not very significant, especially in large chains.

Quench dynamics of entanglement in an open anisotropic spin-12Heisenberg chain

“…The effects of the anisotropy interaction on the evolution of entanglement were investigated [19], as such a global quench can actually be realized for atoms in optical lattices [20]. Moreover, the effects of a bond defect on the entanglement dynamics in a local quench were studied [21] and the evolution of one-dimensional quantum lattice systems was investigated when the ground state was perturbed by altering one site in the middle of the chain [22][23][24][25][26][27]. Recently, Bose exploited global quench dynamics in spin chains for a distant pairwise entanglement, which can be used for quantum communication [28].…”

Quench Dynamics of Entanglement in an Opened Anisotropic Spin-1/2 Heisenberg Chain

“…Moreover, the effects of a bond defect on the entanglement dynamics in a local quench were studied [21] and the evolution of one-dimensional quantum lattice systems was investigated when the ground state was perturbed by altering one site in the middle of the chain [22][23][24][25][26][27].…”

Creation of Stable Multipartite Entangled States in Spin Chains With Defects

“…Moreover, since states (n 1 − 1, n 1 ) and (n 1 , n 1 + 1) are coupled to second order, the interaction strength is small and the detuning rate required to keep the created Bell state with high fidelity does not need to be very large. Several other possibilities for Bell and W states where use is made of the defects and anisotropy have been discussed elsewhere [5,7].…”

“…In principle, the qubit level spacings may be controllable [6], allowing the creation of entanglement between precisely selected qubits. as it turns out, the anisotropy of the system can also be used to our advantage, for states with different numbers of neighboring excited qubits are not coupled and a large system may then be treated as consisting of several uncoupled small chains [5,7].…”