scholarly journals Postponing Distillability Sudden Death in a Correlated Dephasing Channel

Entropy ◽  
2020 ◽  
Vol 22 (8) ◽  
pp. 827
Author(s):  
Guanghao Xue ◽  
Liang Qiu
Keyword(s):  
Sudden Death ◽  
Quantum Channel ◽  
Positive Partial Transpose ◽  
Partial Correlations ◽  
Partial Transpose ◽  
Correlated Channel

We investigated the dynamics of a two-qutrit system in a correlated quantum channel. The partial correlations between consecutive actions of the channel can effectively postpone the phenomenon of distillability sudden death (DSD) and broaden the range of the time cutoff that indicates entanglement of the positive partial transpose states. Particularly, the negativity of the system will revive and DSD will disappear in the fully correlated channel.

scholarly journals Bound entanglement and distillability of multipartite quantum systems

2015 ◽  
Vol 13 (05) ◽  
pp. 1550036 ◽  
Author(s):  
Hui Zhao ◽  
Xin-Yu Yu ◽  
Naihuan Jing
Keyword(s):  
Quantum Systems ◽  
Entangled States ◽  
Multipartite Quantum Systems ◽  
Positive Partial Transpose ◽  
Partial Transpose ◽  
Bound Entanglement

We construct a class of entangled states in ℋ = ℋA ⊗ ℋB ⊗ ℋC quantum systems with dim ℋA = dim ℋB = dim ℋC = 2 and classify those states with respect to their distillability properties. The states are bound entanglement for the bipartite split (AB) - C. The states are non-positive partial transpose (NPT) entanglement and 1-copy undistillable for the bipartite splits A - (BC) and B - (AC). Moreover, we generalize the results of 2 ⊗ 2 ⊗ 2 systems to the case of 2n ⊗ 2n ⊗ 2n systems.

scholarly journals Small sets of locally indistinguishable orthogonal maximally entangled states

2014 ◽  
Vol 14 (13&14) ◽  
pp. 1098-1106
Author(s):  
Alessandro Cosentino ◽  
Vincent Russo
Keyword(s):  
Affirmative Answer ◽  
Semidefinite Program ◽  
Entangled States ◽  
Classical Communication ◽  
Fundamental Interest ◽  
Positive Partial Transpose ◽  
Partial Transpose ◽  
Maximally Entangled States ◽  
First Time

We study the problem of distinguishing quantum states using local operations and classical communication (LOCC). A question of fundamental interest is whether there exist sets of $k \leq d$ orthogonal maximally entangled states in $\complex^{d}\otimes\complex^{d}$ that are not perfectly distinguishable by LOCC. A recent result by Yu, Duan, and Ying [Phys. Rev. Lett. 109 020506 (2012)] gives an affirmative answer for the case $k = d$. We give, for the first time, a proof that such sets of states indeed exist even in the case $k < d$. Our result is constructive and holds for an even wider class of operations known as positive-partial-transpose measurements (PPT). The proof uses the characterization of the PPT-distinguishability problem as a semidefinite program.

scholarly journals Entangling capacities and the geometry of quantum operations

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Jhih-Yuan Kao ◽  
Chung-Hsien Chou
Keyword(s):  
Quantum Information ◽  
Physical Significance ◽  
Quantum States ◽  
Important Class ◽  
Quantum Operation ◽  
Positive Partial Transpose ◽  
Quantum Operations ◽  
Partial Transpose ◽  
Ppt States

Abstract Quantum operations are the fundamental transformations on quantum states. In this work, we study the relation between entangling capacities of operations, geometry of operations, and positive partial transpose (PPT) states, which are an important class of states in quantum information. We show a method to calculate bounds for entangling capacity, the amount of entanglement that can be produced by a quantum operation, in terms of negativity, a measure of entanglement. The bounds of entangling capacity are found to be associated with how non-PPT (PPT preserving) an operation is. A length that quantifies both entangling capacity/entanglement and PPT-ness of an operation or state can be defined, establishing a geometry characterized by PPT-ness. The distance derived from the length bounds the relative entangling capability, endowing the geometry with more physical significance. We also demonstrate the equivalence of PPT-ness and separability for unitary operations.

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