On isotropic states in α-LiNH4SO4 crystals

2014 ◽  
Vol 117 (5) ◽  
pp. 756-758 ◽  
Author(s):  
V. Yo. Stadnyk ◽  
R. S. Brezvin ◽  
M. Ya. Rudysh ◽  
P. A. Shchepanskyi ◽  
V. M. Gaba ◽  
...  
Keyword(s):  
Isotropic States

scholarly journals BEST SEPARABLE APPROXIMATION WITH SEMI-DEFINITE PROGRAMMING METHOD

2004 ◽  
Vol 02 (04) ◽  
pp. 541-558 ◽  
Author(s):  
M. A. JAFARIZADEH ◽  
M. MIRZAEE ◽  
M. REZAEE
Keyword(s):  
Mixed State ◽  
Qubit State ◽  
Programming Method ◽  
Simple Analytical Expression ◽  
Analytical Expression ◽  
Isotropic State ◽  
Separable Approximation ◽  
Isotropic States

The present methods for obtaining the optimal Lewenestein–Sanpera decomposition of a mixed state are difficult to handle analytically. We provide a simple analytical expression for the optimal Lewenstein–Sanpera decomposition by using semi-definite programming. In particular, we obtain the optimal Lewenstein–Sanpera decomposition for some examples such as: the Bell decomposable state, the iso-concurrence state, the generic two-qubit state in the Wootters basis, the 2⊗3 Bell decomposable state, the d⊗d Werner and isotropic states, a one parameter 3⊗3 state, and finally a multi-partite isotropic state.

Quantum correlation based on weak measurements

2017 ◽  
Vol 15 (06) ◽  
pp. 1750041 ◽  
Author(s):  
Yangyang Wang ◽  
Jinchuan Hou ◽  
Xiaofei Qi
Keyword(s):  
Pure State ◽  
Quantum Correlation ◽  
Qubit State ◽  
Sufficient Condition ◽  
Product State ◽  
Necessary And Sufficient Condition ◽  
Weak Measurements ◽  
Werner States ◽  
Necessary And Sufficient ◽  
Isotropic States

A quantum correlation [Formula: see text] based on weak measurements for bipartite systems is introduced. It is shown that the product states do not contain this quantum correlation. Also, the necessary and sufficient condition for any two-qubit state becoming a product state is obtained. The quantum correlation [Formula: see text] and other quantum correlation for two-qubit entangled pure state, Werner states and isotropic states are compared.

QUANTUM DISCORD DERIVED FROM TSALLIS ENTROPY

2013 ◽  
Vol 11 (01) ◽  
pp. 1350013 ◽  
Author(s):  
JACEK JURKOWSKI
Keyword(s):  
Probability Theory ◽  
Quantum Theory ◽  
Quantum Discord ◽  
Tsallis Entropy ◽  
Classical Probability ◽  
Analytical Expression ◽  
Classical Probability Theory ◽  
Definition Of ◽  
Isotropic States

Due to some ambiguity in the definition of mutual Tsallis entropy in classical probability theory, its generalization to quantum theory is discussed and, as a consequence, two types of generalized quantum discords, called q-discords, are defined in terms of quantum Tsallis entropy. Both q-discords for two-qubit Werner and isotropic states are determined and compared and it is shown that one of them is non-negative, at least for states under investigation, for all q > 0. Finally, an analytical expression for q-discord of certain family of two-qubit X-states is presented. Using this example, we show that both types of q-discords can take negative values for some q > 1, hence their use as correlations measures is rather limited.

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