scholarly journals Negative quantum conditional entropy and the entanglement measure of a kind of mixed state of bipartite quantum system

2007 ◽  
Vol 56 (7) ◽  
pp. 3937
Author(s):  
Zhou Bing-Ju ◽  
Liu Xiao-Juan ◽  
Fang Mao-Fa ◽  
Zhou Qing-Ping ◽  
Liu Ming-Wei
Keyword(s):  
Quantum System ◽  
Mixed State ◽  
Conditional Entropy ◽  
Entanglement Measure ◽  
Bipartite Quantum System ◽  
Quantum Conditional Entropy

scholarly journals Extracting classical correlations from a bipartite quantum system

2003 ◽  
Vol 67 (1) ◽  
Author(s):  
S. Hamieh ◽  
J. Qi ◽  
D. Siminovitch ◽  
M. K. Ali
Keyword(s):  
Quantum System ◽  
Bipartite Quantum System ◽  
Classical Correlations

scholarly journals Experimental Implications of Negative Quantum Conditional Entropy—H2 Mobility in Nanoporous Materials

2020 ◽  
Vol 10 (22) ◽  
pp. 8266
Author(s):  
C. Aris Chatzidimitriou-Dreismann
Keyword(s):  
Information Theory ◽  
Translational Motion ◽  
Conditional Entropy ◽  
Classical Case ◽  
Quantum Thermodynamics ◽  
Incoherent Neutron Scattering ◽  
Quantum Conditional Entropy ◽  
Del Rio ◽  
Incoherent Neutron ◽  
Fictitious Particle

During the last few decades, considerable advances in quantum information theory have shown deep existing connections between quantum correlation effects (like entanglement and quantum discord) and thermodynamics. Here the concept of conditional entropy plays a considerable role. In contrast to the classical case, quantum conditional entropy can take negative values. This counter-intuitive feature, already well understood in the context of information theory, was recently shown theoretically to also have a physical meaning in quantum thermodynamics [del Rio et al. Nature 2011, 474, 61]. Extending this existing work, here we provide evidence of the significance of negative conditional entropy in a concrete experimental context: Incoherent Neutron Scattering (INS) from protons of H2 in nano-scale environments; e.g., in INS from H2 in C-nanotubes, the data of the H2 translational motion along the nanotube axis seems to show that the neutron apparently scatters from a fictitious particle with mass of 0.64 atomic mass units (a.m.u.)—instead of the value of 2 a.m.u. as conventionally expected. An independent second experiment confirms this finding. However, taking into account the possible negativity of conditional entropy, we explain that this effect has a natural interpretation in terms of quantum thermodynamics. Moreover, it is intrinsically related to the number of qubits capturing the interaction of the two quantum systems H2 and C-nanotube. The considered effect may have technological applications (e.g., in H-storage materials and fuel cells).

scholarly journals Locally indistinguishable orthogonal product bases in arbitrary bipartite quantum system

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Guang-Bao Xu ◽  
Ying-Hui Yang ◽  
Qiao-Yan Wen ◽  
Su-Juan Qin ◽  
Fei Gao
Keyword(s):  
Quantum System ◽  
Bipartite Quantum System ◽  
Orthogonal Product

scholarly journals Quantumness of States and Unitary Operations

2020 ◽  
Vol 50 (11) ◽  
pp. 1645-1685
Author(s):  
Joanna Luc
Keyword(s):  
Quantum Entanglement ◽  
Mixed State ◽  
Unitary Transformation ◽  
Quantum Discord ◽  
Conditional Entropy ◽  
Quantum States ◽  
Qubit State

AbstractThis paper investigates various properties that may by possessed by quantum states, which are believed to be specifically “quantum” (entanglement, nonlocality, steerability, negative conditional entropy, non-zero quantum discord, non-zero quantum super discord and contextuality) and their opposites. It also considers their “absolute” counterparts in the following sense: a given state has a given property absolutely if after an arbitrary unitary transformation it still possesses it. The known relations between the listed properties and between their absolute counterparts are summarized. It is proven that the only two-qubit state that has zero quantum discord absolutely is the maximally mixed state. Finally, related conceptual issues concerning the terms “classical” and “quantum” are discussed.

COMPLEMENTARITY AND THE ALGEBRAIC STRUCTURE OF FOUR-LEVEL QUANTUM SYSTEMS

2009 ◽  
Vol 12 (01) ◽  
pp. 99-116 ◽  
Author(s):  
DÉNES PETZ ◽  
ANDRÁS SZÁNTÓ ◽  
MIHÁLY WEINER
Keyword(s):  
Quantum System ◽  
Algebraic Structure ◽  
Conditional Entropy ◽  
Quantum Systems ◽  
History Of ◽  
Bell Basis

The history of complementary observables and mutual unbiased bases is shortly reviewed. A characterization is given in terms of conditional entropy of subalgebras due to Connes and Størmer. The extension of complementarity to noncommutative subalgebras is considered as well. Possible complementary decompositions of a four-level quantum system are described and a characterization of the Bell basis is obtained: The MASA generated by the Bell basis is complementary to both M2(ℂ) tensor factors.

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