On Magnetic Entanglement

We investigate global entanglement in the ground state of single-molecular magnet Na 9 [Cu 3 Na 3 (H 2 O) 9 (α-AsW 9 O 33 ) 2 ]·26H 2 O with an external magnetic field. The concurrence, tangle, and measure function Q , which characterize the pairwise entanglement, 3-party entanglement and total entanglement, respectively, are calculated numerically at zero temperature. The results show that the magnitude and direction of the applied magnetic field play a significant role in the properties of three kinds of entanglement measures. We give a physical interpretation of the variation of the global entanglement with the magnetic field. Finally, the phase diagram of the global entanglement characterized by the critical magnetic fields is presented.We investigate global entanglement in the ground state of single-molecular magnet Na 9 [Cu 3 Na 3 (H 2 O) 9 (α-AsW 9 O 33 ) 2 ]·26H 2 O with an external magnetic field. The concurrence, tangle, and measure function Q , which characterize the pairwise entanglement, 3-party entanglement and total entanglement, respectively, are calculated numerically at zero temperature. The results show that the magnitude and direction of the applied magnetic field play a significant role in the properties of three kinds of entanglement measures. We give a physical interpretation of the variation of the global entanglement with the magnetic field. Finally, the phase diagram of the global entanglement characterized by the critical magnetic fields is presented.

Chinese Physics BJul 1, 20141 citation

Quantum Entanglement

Meron Hailom, Misty Moore

Aug 8, 20180 citations

Entanglement Evolution in a Heisenberg Spin Dimer

Jin Wang, Magnolia Landman, Thomas Sutter +1 more

The transitory and steady-state entanglement of a two-qubit XY Heisenberg magnetic spin system immersed in an external magnetic field are analyzed in terms of the entanglement measure of concurrence. The dependence of the system entanglement on coupling strength, decay rate, and applied magnetic field is numerically simulated for two distinct models of system evolution involving decoherence to the environment. An applied magnetic field was found to consistently reduce the system entropy. The external magnetic field increases entanglement for small strength, and if too strong, it reduces the entanglement. The maximum entanglement is formed from a balance of external magnetic field and the decay rate. The transitory level of entanglement in the system is found to oscillate with a frequency that is proportional to the magnetic field strength before reaching steady-state entanglement. It was found that collective decay produces more entanglement than individual decay.The transitory and steady-state entanglement of a two-qubit XY Heisenberg magnetic spin system immersed in an external magnetic field are analyzed in terms of the entanglement measure of concurrence. The dependence of the system entanglement on coupling strength, decay rate, and applied magnetic field is numerically simulated for two distinct models of system evolution involving decoherence to the environment. An applied magnetic field was found to consistently reduce the system entropy. The external magnetic field increases entanglement for small strength, and if too strong, it reduces the entanglement. The maximum entanglement is formed from a balance of external magnetic field and the decay rate. The transitory level of entanglement in the system is found to oscillate with a frequency that is proportional to the magnetic field strength before reaching steady-state entanglement. It was found that collective decay produces more entanglement than individual decay.

IEEE Transactions on MagneticsNov 18, 20195 citations

Witnessing macroscopic entanglement in a staggered magnetic field

Jenny Hide, Wonmin Son, Ian D. Lawrie +1 more

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.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.

arXiv:quant-ph/0701013Physical Review AAug 20, 200716 citations

Quantum Entanglement

WORLD SCIENTIFIC eBooksMar 27, 20180 citations

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.