Mi-Ra Hwang

Greenberger-Horne-Zeilinger versus W states : Quantum teleportation through noisy channels

Eylee Jung, Mi-Ra Hwang, You Hwan Ju, Min-Soo Kim, Sahng-Kyoon Yoo, Hungsoo Kim, D. K. Park, Jin-Woo Son, S. Tamaryan, Seong-Keuck Cha 1 Department of Physics, Kyungnam University, Masan, 631-701, Korea 2 Department of Mathematics, Kyungnam University, Masan, 631-701, Korea 3 Green University, Hamyang, 676-872, Korea 4 The Institute of Basic Science, Kyungnam University, Masan, 631-701, Korea 5 Theory Department, Yerevan Physics Institute, Yerevan-36, 375036, Armenia 6 Department of Chemistry, Kyungnam University, Masan, 631-701, Korea Abstract Which state does lose less quantum information between GHZ and W states when they are prepared for two-party quantum teleportation through noisy channel? We address this issue by solving analytically a master equation in the Lindbald form with introducing the noisy channels which makes the quantum channels to be mixed states. It is found that the answer of the question is dependent on the type of the noisy channel. If, for example, the noisy channel is (L2,x, L3,x, L4,x)-type where L s denote the Lindbald operators, GHZ state is always more robust than W state, i.e. GHZ state preserves more quantum information. In, however, (L2,y, L3,y, L4,y)-type channel the situation becomes completely reversed. In (L2,z, L3,z, L4,z)-type channel W state is more robust than GHZ state when the noisy parameter (κ) is comparatively small while GHZ state becomes more robust when κ is large. In isotropic noisy channel we found that both states preserve equal amount of quantum information. A relation between the average fidelity and entanglement for the mixed state quantum channels are discussed.

Tripartite entanglement in a noninertial frame

Tripartite entanglement is examined when one of the three parties moves with a uniform acceleration with respect to other parties. As the Unruh effect indicates, tripartite entanglement exhibits a decreasing behavior with increasing acceleration. Unlike bipartite entanglement, however, tripartite entanglement does not completely vanish in the infinite acceleration limit. If the three parties, for example, share the Greenberger-Horne-Zeilinger or

Three-tangle for rank-three mixed states: Mixture of Greenberger-Horne-Zeilinger, W , and flipped- W states

W

Mixed-state entanglement and quantum teleportation through noisy channels

state initially, the corresponding

Reduced state uniquely defines the Groverian measure of the original pure state

\ensuremath{\pi}

Three-tangle in non-inertial frame

-tangle, one of the measures of tripartite entanglement, is shown to be

Toward an understanding of entanglement for generalized n-qubit W-states

\ensuremath{\pi}/6~0.524

Attack of many eavesdroppers via optimal strategy in quantum cryptography

or

QUANTUM DISCORD AND QUANTUM ENTANGLEMENT IN THE PRESENCE OF AN ASYMPTOTICALLY FLAT STATIC BLACK HOLE

0.176

The Aharonov?Bohm?Coulomb problem in a graphene ring

in this limit, respectively. This fact indicates that tripartite quantum-information processing may be possible even if one of the parties approaches the Rindler horizon. The physical implications of this striking result are discussed in the context of black-hole physics.