arXiv:quant-ph/0403135 · Physical Review A

Entanglement at the boundary of spin chains near a quantum critical point and in systems with boundary critical points

Tobias Stauber, F. Guinea

Published Aug 19, 2004• 15 citations

Abstract

We analyze the entanglement properties of spins (qubits) attached to the boundary of spin chains near quantum critical points, or to dissipative environments, near a boundary critical point, such as Kondo-like systems or the dissipative two level system. In the first case, we show that the properties of the entanglement are significantly different from those for bulk spins. The influence of the proximity to a transition is less marked at the boundary. In the second case, our results indicate that the entanglement changes abruptly at the point where coherent quantum oscillations cease to exist. The phase transition modifies the entanglement significantly less.

DOI: 10.1103/physreva.70.022313

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arXiv:quant-ph/0403135 · Physical Review A

Entanglement at the boundary of spin chains near a quantum critical point and in systems with boundary critical points

Tobias Stauber, F. Guinea

Published Aug 19, 2004• 15 citations

arXiv HTML PDF

Abstract

DOI: 10.1103/physreva.70.022313

Related papers

Entanglement of spin chains with general boundaries and of dissipative systems

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g

of the states passes through a critical point. Such a point can be called a point of quantum phase transition, since at this point the character of the matrix-product state, which is the ground state of a Hamiltonian, changes discontinuously. We also study the finite size effects and show how the entanglement depends on the size of the chain. This later part is relevant to the field of quantum computation where the problem of initial state preparation in finite arrays of qubits or qutrits is important. It is also shown that the entanglement of two sites have scaling behavior near the critical point.

The ground entanglement and thermal entanglement in quantum mixed spin chains consisting of two integer spins 1 and two half-integer spins

\frac{1}{2}

arrayed as $\frac{1}{2}\text{\ensuremath{-}}\frac{1}{2}\text{\ensuremath{-}}1\text{\ensuremath{-}}1$ in a unit cell with antiferromagnetic nearest-neighbor couplings

{J}_{1}

({J}_{2})

between the spins of equal (different) magnitudes are investigated by employing the logarithmic negativity as entanglement measure. The ground entanglement transition found here is closely related to the valence-bond-solid phase transition, and the thermal entanglement near the critical point is calculated and it is shown that two distinct behaviors exist in the nearest-neighbor same kind of spins and different kind of spins, respectively.