Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:quant-ph/0701013 · Physical Review A

Witnessing macroscopic entanglement in a staggered magnetic field

Jenny Hide, Wonmin Son, Ian D. Lawrie, Vlatko Vedral

Published Aug 20, 2007• 16 citations
arXivHTMLPDF

Abstract

We investigate macroscopic entanglement in an infinite XX spin-$\frac{1}{2}$ chain with staggered magnetic field, ${B}_{l}=B+{e}^{\ensuremath{-}i\ensuremath{\pi}l}b$. 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.

DOI
10.1103/physreva.76.022319

Related papers

Effects of Staggered Magnetic Field on Entanglement in the Anisotropic XY Model

Sun Zhe, Xiaoguang Wang

We investigate effects of staggered magnetic field on thermal entanglement in the anisotropic XY model. The analytic results of entanglement for the two-site cases are obtained. For the general case of even sites, we show that when the anisotropic parameter is zero, the entanglement in the XY model with a staggered magnetic field is the same as that with a uniform magnetic field.

Communications in Theoretical Physics•Jan 1, 2006•3 citations

Effects of staggered magnetic field on entanglement in the anisotropic XY model

Sun, Zhe, Xiaoguang Wang, You‐Quan Li

We investigate effects of staggered magnetic field on thermal entanglement in the anisotropic XY model. The analytic results of entanglement for the two-site cases are obtained. For the general case of even sites, we show that when the anisotropic parameter is zero, the entanglement in the XY model with a staggered magnetic field is the same as that with a uniform magnetic field.

arXiv:quant-ph/0409166•Sep 25, 2004•0 citations

Entanglement propagation through spin chains in the presence of a staggered magnetic field

R. H. Crooks, Dmitri V. Khveshchenko

We study the dynamics of entanglement in an $XY$ spin chain subject to a staggered magnetic field and contrast it to the previously discussed uniform field case. We find that in the isotropic $(XX)$ limit a staggered field can provide almost equally favorable conditions for a high-fidelity transfer of entanglement, while even a modest amount of exchange anisotropy appears to have a strong detrimental effect. We also study interactions between different waves of entanglement and assess the possibility of simultaneous transmission of multiple bits of quantum information.

arXiv:0712.4349•Physical Review A•Jun 3, 2008•13 citations

Entanglement and the interplay between staggered fields and couplings

Jenny Hide, Yoshifumi Nakata, Mio Murao

We investigate how the interplay between a staggered magnetic field and staggered coupling strength affects both ground-state and thermal entanglement. Upon analytically calculating thermodynamic quantities and the correlation functions for such a system, we consider both the global Meyer-Wallach measure of entanglement and the concurrence between pairs of spins. We discover two quantum critical points present in the model and show that the behavior of entanglement at zero temperature reflects each. We discover that increasing the alternating field and alternating coupling strength can actually increase the amount of entanglement present both at zero temperature and for thermal states of the system.

arXiv:1201.4251•Physical Review A•Apr 4, 2012•6 citations

Staggered magnetization and entanglement enhancement by magnetic impurities in S=1/2 spin chain

APOLLARO T. J. G, CUCCOLI A, Andrea Fubini +2 more

We study the effects of an impurity on the magnetic response and the entanglement properties of the infinite S=1/2 XX chain in a transverse field h in its quasi-long-range ordered phase, i.e., below the critical point h=1. We show that regardless of the sign of the exchange coupling, and for whatever value of the applied field, the impurity generates an oscillating magnetization that displays a power-law decay with the distance from the impurity itself. This effect sensibly modifies the overall magnetic behavior of the chain, as testified by the observed rounding-off of the divergence of the longitudinal susceptibility. Moreover, the emergence of the above alternating structure in the spin configuration entails a substantial change in the pairwise entanglement distribution along the chain, so that concurrences are found either enhanced (up to a factor larger than 2) or quenched, depending on the distance of the spin pair from the impurity, on its strength, and on the value of the magnetic field. Acting on such control parameters, an adiabatic manipulation of both the magnetic and entanglement properties can be performed. We find these effects robust against thermal fluctuations, and we can therefore suggest realistic setups to experimentally probe the predicted behavior.

•Jan 1, 2008•0 citations

Thermal entanglement between alternate qubits of a four-qubit Heisenberg XX chain in a magnetic field

Min Cao, Shiqun Zhu

The concurrence of two alternate qubits in a four-qubit Heisenberg $XX$ chain is investigated when a uniform magnetic field $B$ is included. It is found that there is no thermal entanglement between alternate qubits if $B$ is close to zero. A magnetic field can induce entanglement in a certain range both for the antiferromagnetic and ferromagnetic cases. Near zero temperature, the entanglement undergoes two sudden changes with increasing value of the magnetic field $B$. This is due to the changes in the ground state. This novel property may be used as a quantum entanglement switch. The anisotropy in the system can also induce the entanglement between two alternate qubits.

arXiv:quant-ph/0501029•Physical Review A•Mar 24, 2005•61 citations
We investigate macroscopic entanglement in an infinite XX spin-12\frac{1}{2}21​ chain with staggered magnetic field, Bl=B+e\ensuremath−i\ensuremathπlb{B}_{l}=B+{e}^{\ensuremath{-}i\ensuremath{\pi}l}bBl​=B+e\ensuremath−i\ensuremathπlb. 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 bbb is, in general, to suppress entanglement as do BBB and TTT, we find that when T=0T=0T=0, introducing bbb allows the existence of entanglement even when the uniform magnetic field BBB 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.
We study the dynamics of entanglement in an XYXYXY spin chain subject to a staggered magnetic field and contrast it to the previously discussed uniform field case. We find that in the isotropic (XX)(XX)(XX) limit a staggered field can provide almost equally favorable conditions for a high-fidelity transfer of entanglement, while even a modest amount of exchange anisotropy appears to have a strong detrimental effect. We also study interactions between different waves of entanglement and assess the possibility of simultaneous transmission of multiple bits of quantum information.
We investigate how the interplay between a staggered magnetic field and staggered coupling strength affects both ground-state and thermal entanglement. Upon analytically calculating thermodynamic quantities and the correlation functions for such a system, we consider both the global Meyer-Wallach measure of entanglement and the concurrence between pairs of spins. We discover two quantum critical points present in the model and show that the behavior of entanglement at zero temperature reflects each. We discover that increasing the alternating field and alternating coupling strength can actually increase the amount of entanglement present both at zero temperature and for thermal states of the system.
We study the effects of an impurity on the magnetic response and the entanglement properties of the infinite S=1/2 XX chain in a transverse field h in its quasi-long-range ordered phase, i.e., below the critical point h=1. We show that regardless of the sign of the exchange coupling, and for whatever value of the applied field, the impurity generates an oscillating magnetization that displays a power-law decay with the distance from the impurity itself. This effect sensibly modifies the overall magnetic behavior of the chain, as testified by the observed rounding-off of the divergence of the longitudinal susceptibility. Moreover, the emergence of the above alternating structure in the spin configuration entails a substantial change in the pairwise entanglement distribution along the chain, so that concurrences are found either enhanced (up to a factor larger than 2) or quenched, depending on the distance of the spin pair from the impurity, on its strength, and on the value of the magnetic field. Acting on such control parameters, an adiabatic manipulation of both the magnetic and entanglement properties can be performed. We find these effects robust against thermal fluctuations, and we can therefore suggest realistic setups to experimentally probe the predicted behavior.
The concurrence of two alternate qubits in a four-qubit Heisenberg XXXXXX chain is investigated when a uniform magnetic field BBB is included. It is found that there is no thermal entanglement between alternate qubits if BBB is close to zero. A magnetic field can induce entanglement in a certain range both for the antiferromagnetic and ferromagnetic cases. Near zero temperature, the entanglement undergoes two sudden changes with increasing value of the magnetic field BBB. This is due to the changes in the ground state. This novel property may be used as a quantum entanglement switch. The anisotropy in the system can also induce the entanglement between two alternate qubits.