On the possibility to detect quantum correlation regions with the variable optimal measurement angle

Gramegna, Marco; Yurischev, M. A.

doi:10.1140/epjd/e2019-90451-3

Cited by 2 publications

(3 citation statements)

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“…( 34) we get F = 0.985645 (≈ 98.6%) between the above points. One may conclude from here that the region with the variable optimal measurement angle is broad enough and can be detected on an experiment (see in this connection [39]).…”

Section: The Case J Z = −|J|supporting

confidence: 51%

Temperature-field phase diagrams of one-way quantum work deficit in two-qubit XXZ spin systems

Yurischev

2020

Quantum Inf Process

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The spin-1/2 XXZ chain in a uniform magnetic field at thermal equilibrium is considered. For this model, we give a complete classification of all qualitatively different phase diagrams for the one-way quantum work (information) deficit. The diagrams can contain regions (phases, fractions) with both stationary and variable (state-dependent) angles of optimal measurement. We found cases of phase diagrams in which the sizes of regions with the variable optimal measurement angle are large and perhaps such regions can be detected experimentally. We also established a relationship between the behavior of optimal measurement angles near the boundaries separated different regions and Landau's theory of phase transitions of the second and first kind.Keywords X density matrix · Quantum correlation function · Piecewisedefined function · Subdomains and phase diagram · Critical lines and boundaries between subdomaines Mathematics Subject Classification (2010) Primary 81P40 · Secondary 81Qxx 1 IntroductionQuantum correlations have foundational interest and are an essential resource for quantum information and computational technologies. There are many measures of quantum correlations. One of the most important places among them belongs to the quantum discord and one-way quantum work deficit [1,2,3,4,5]. It is significant that the concept of these correlations, as opposed to

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Section: The Case J Z = −|J|supporting

confidence: 51%

Temperature-field phase diagrams of one-way quantum work deficit in two-qubit XXZ spin systems

Yurischev

2020

Quantum Inf Process

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“…Comparing the main terms of the expansions (33) and (36), we conclude that for T → ∞ the deficit will be determined by the ∆ 0 -branch, if J 2 z + B 2 > J 2 , and by…”

Section: Sudden Transitions Of Work Deficitmentioning

confidence: 89%

“…In Ref. [33], we proposed an optical setup scheme and performed numerical simulations that showed that the mysterious domain with variable optimal parameter may be detected experimentally using existing modern optical means.…”

Section: Introductionmentioning

confidence: 99%

Landau-type sudden transitions of quantum correlations

Yurischev

2022

Preprint

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Sudden changes of quantum correlations in the Bell-diagonal states are well-known effects. They occur when the set of optimal parameters that determine the quantum correlation consists of isolated points and optimal parameters during the evolution of the system jump from one such point to another (e.g., the optimal measurement angle of the quantum discord changes discontinuously from zero to π/2 or vice versa). However, when considering more general X quantum states, we found that quantum discord and one-way quantum work deficit can experience sudden changes of other kinds. Namely, the optimal measurement angle may suddenly start to shift continuously from its stationary value 0 or π/2 to an intermediate optimal measurement angle ϑ ∈ (0, π/2). This leads to a new behavior of quantum correlations, which is mathematically described by the Landau phenomenological theory of second-order phase transitions. In addition, for the one-way quantum work deficit, we found cases where the optimal measurement angle jumps from zero to a nonzero step less than π/2, and then continuously changes its value. This behavior of quantum correlation is similar to a first-order phase transition in Landau's theory. Dependencies of quantum discord and one-way quantum work deficit near the boundaries, which separate regions with state-dependent (variable) and state-independent (stationary, constant) optimal measurement angles, are examined in detail on an example of the XXZ spin model in an external field at thermal equilibrium.

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On the possibility to detect quantum correlation regions with the variable optimal measurement angle

Cited by 2 publications

References 58 publications

Temperature-field phase diagrams of one-way quantum work deficit in two-qubit XXZ spin systems

Temperature-field phase diagrams of one-way quantum work deficit in two-qubit XXZ spin systems

Landau-type sudden transitions of quantum correlations

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