scholarly journals Thermal entanglement in a {Cu3} single molecular magnet in the magnetic field

2013 ◽  
Vol 62 (19) ◽  
pp. 190302
Author(s):  
Li Ji-Qiang ◽  
Cheng Zhi ◽  
Zhou Bin
Keyword(s):  
Magnetic Field ◽  
Molecular Magnet ◽  
Thermal Entanglement ◽  
The Magnetic Field

The dynamics of tripartite quantum correlations under Ornstein–Uhlenbeck noise

2018 ◽  
Vol 32 (31) ◽  
pp. 1850381 ◽  
Author(s):  
Jing Yang ◽  
Qi-Xiong Mu ◽  
Yan-Xia Huang
Keyword(s):  
Magnetic Field ◽  
Sudden Death ◽  
Quantum Correlation ◽  
Quantum Correlations ◽  
Time Limit ◽  
Entanglement Sudden Death ◽  
Thermal Entanglement ◽  
Short Time ◽  
The Magnetic Field ◽  
Markov Limit

The dynamics of the tripartite thermal entanglement measured by Negativity (N) and the tripartite quantum correlation described by measurement-induced disturbance (MID) under Ornstein–Uhlenbeck noise are investigated. This study has found that the tripartite N and MID can be preserved more effectively in the non-Markovian environment than in the short-time limit and the Markov limit cases. The short-time limit is a better approximation than the Markov limit. MID vanishes only in the asymptotic limit, while entanglement sudden death may occur, and the decreasing duration of MID far outweighs entanglement. This implies that MID is more robust than Negativity. As the noise bandwidth increases, the disentanglement time and the decay time of MID are significantly shorter. The increase of XZX[Formula: see text]+[Formula: see text]YZY three-site interaction is more effective than XZY−YZX three-site interaction to enhance Negativity and MID as well as the disentanglement time. The magnetic field diminishes Negativity and MID, but has no significant influence on the decreasing durations of both Negativity and MID.

Thermal Entanglement and Dense Coding in Two-Qubit XX Spin Chain under an Arbitrary Magnetic Field

2013 ◽  
Vol 446-447 ◽  
pp. 986-991
Author(s):  
Hai Lin Huang ◽  
Zhao Yu Sun
Keyword(s):  
Magnetic Field ◽  
Thermal State ◽  
Arbitrary Orientation ◽  
Dense Coding ◽  
Thermal Entanglement ◽  
Optimal Direction ◽  
Optimal Dense Coding ◽  
Arbitrary Magnetic Field ◽  
Coding Capacity ◽  
The Magnetic Field

The effect of arbitrary orientation in the magnetic field on the entanglement and dense coding of a two-qubit XX model is investigated. The concurrence and optimal dense coding capacity are calculated for different orientations of the magnetic field. It is found that the entanglement can be maximized by rotating the magnetic field to an optimal direction at given temperature. Furthermore, there exists critical concurrence Cc, beyond which the thermal state is unfeasible for optimal dense coding.

scholarly journals Magnetic-Field-Orientation Dependent Thermal Entanglement of a Spin-1 Heisenberg Dimer: The Case Study of Dinuclear Nickel Complex with an Uniaxial Single-Ion Anisotropy

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3420
Author(s):  
Azadeh Ghannadan ◽  
Jozef Strečka
Keyword(s):  
Magnetic Field ◽  
Nickel Complex ◽  
Energy Gap ◽  
Ground States ◽  
Quantum Spin ◽  
Thermal Entanglement ◽  
Bipartite Entanglement ◽  
Field Orientation ◽  
Magnetic Field Orientation ◽  
The Magnetic Field

The bipartite entanglement in pure and mixed states of a quantum spin-1 Heisenberg dimer with exchange and uniaxial single-ion anisotropies is quantified through the negativity in a presence of the external magnetic field. At zero temperature the negativity shows a marked stepwise dependence on a magnetic field with two abrupt jumps and plateaus, which can be attributed to the quantum antiferromagnetic and quantum ferrimagnetic ground states. The magnetic-field-driven phase transition between the quantum antiferromagnetic and quantum ferrimagnetic ground states manifests itself at nonzero temperatures by a local minimum of the negativity, which is followed by a peculiar field-induced rise of the negativity observable in a range of moderately strong magnetic fields. The rising temperature generally smears out abrupt jumps and plateaus of the negativity, which cannot be distinguished in the relevant dependencies above a certain temperature. It is shown that the thermal entanglement is most persistent against rising temperature at the magnetic field, for which an energy gap between a ground state and a first excited state is highest. Besides, temperature variations of the negativity of the spin-1 Heisenberg dimer with an easy-axis single-ion anisotropy may exhibit a singular point-kink, at which the negativity has discontinuity in its first derivative. The homodinuclear nickel complex [Ni2(Medpt)2(μ-ox)(H2O)2](ClO4)2·2H2O provides a suitable experimental platform of the antiferromagnetic spin-1 Heisenberg dimer, which allowed us to estimate a strength of the bipartite entanglement between two exchange-coupled Ni2+ magnetic ions on the grounds of the interaction constants reported previously from the fitting procedure of the magnetization data. It is verified that the negativity of this dinuclear compound is highly magnetic-field-orientation dependent due to presence of a relatively strong uniaxial single-ion anisotropy.

scholarly journals THERMAL ENTANGLEMENT IN A TWO-QUTRIT SYSTEM WITH NONLINEAR COUPLING UNDER NONUNIFORM EXTERNAL MAGNETIC FIELD

2008 ◽  
Vol 06 (04) ◽  
pp. 867-884 ◽  
Author(s):  
IMAN SARGOLZAHI ◽  
SAYYED YAHYA MIRAFZALI ◽  
MOHSEN SARBISHAEI
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Lower Bounds ◽  
Threshold Temperature ◽  
Nonlinear Coupling ◽  
Dense Coding ◽  
Thermal Entanglement ◽  
Finite Dimensional ◽  
Coding Capacity ◽  
The Magnetic Field

We study the thermal entanglement of a 2-qutrit spin chain with nonlinear coupling in the presence of nonuniform magnetic field. Thermal entanglement of an arbitrary (finite-dimensional) m-partite system vanishes at some finite threshold temperature Ts. We investigate the dependence of Ts on the system's parameters, i.e. the nonlinear coupling and the magnetic field, for this 2-qutrit system. In addition, we compare two lower bounds of I-concurrence for this system and also study its dense coding capacity as a function of system's parameters.

Observing the galactic magnetic field

1967 ◽  
Vol 31 ◽  
pp. 375-380
Author(s):  
H. C. van de Hulst
Keyword(s):  
Magnetic Field ◽  
Fair Agreement ◽  
Solar Neighbourhood ◽  
Galactic Magnetic Field ◽  
The Magnetic Field

Various methods of observing the galactic magnetic field are reviewed, and their results summarized. There is fair agreement about the direction of the magnetic field in the solar neighbourhood:l= 50° to 80°; the strength of the field in the disk is of the order of 10-5gauss.

Evolution of Large-Scale Coronal Structures

1994 ◽  
Vol 144 ◽  
pp. 29-33
Author(s):  
P. Ambrož
Keyword(s):  
Magnetic Field ◽  
Field Line ◽  
Large Scale ◽  
Coronal Magnetic Field ◽  
Source Surface ◽  
Solar Cycles ◽  
Characteristic Relationship ◽  
The Magnetic Field ◽  
Coronal Structures

AbstractThe large-scale coronal structures observed during the sporadically visible solar eclipses were compared with the numerically extrapolated field-line structures of coronal magnetic field. A characteristic relationship between the observed structures of coronal plasma and the magnetic field line configurations was determined. The long-term evolution of large scale coronal structures inferred from photospheric magnetic observations in the course of 11- and 22-year solar cycles is described.Some known parameters, such as the source surface radius, or coronal rotation rate are discussed and actually interpreted. A relation between the large-scale photospheric magnetic field evolution and the coronal structure rearrangement is demonstrated.

Emergence of Twisted Magnetic Flux Related Sigmoidal Brightening

2000 ◽  
Vol 179 ◽  
pp. 263-264
Author(s):  
K. Sundara Raman ◽  
K. B. Ramesh ◽  
R. Selvendran ◽  
P. S. M. Aleem ◽  
K. M. Hiremath
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Flux ◽  
Ultra Violet ◽  
Active Regions ◽  
Morphological Properties ◽  
Energy Storage And Conversion ◽  
The Sun ◽  
X Rays ◽  
The Magnetic Field

Extended AbstractWe have examined the morphological properties of a sigmoid associated with an SXR (soft X-ray) flare. The sigmoid is cospatial with the EUV (extreme ultra violet) images and in the optical part lies along an S-shaped Hαfilament. The photoheliogram shows flux emergence within an existingδtype sunspot which has caused the rotation of the umbrae giving rise to the sigmoidal brightening.It is now widely accepted that flares derive their energy from the magnetic fields of the active regions and coronal levels are considered to be the flare sites. But still a satisfactory understanding of the flare processes has not been achieved because of the difficulties encountered to predict and estimate the probability of flare eruptions. The convection flows and vortices below the photosphere transport and concentrate magnetic field, which subsequently appear as active regions in the photosphere (Rust & Kumar 1994 and the references therein). Successive emergence of magnetic flux, twist the field, creating flare productive magnetic shear and has been studied by many authors (Sundara Ramanet al.1998 and the references therein). Hence, it is considered that the flare is powered by the energy stored in the twisted magnetic flux tubes (Kurokawa 1996 and the references therein). Rust & Kumar (1996) named the S-shaped bright coronal loops that appear in soft X-rays as ‘Sigmoids’ and concluded that this S-shaped distortion is due to the twist developed in the magnetic field lines. These transient sigmoidal features tell a great deal about unstable coronal magnetic fields, as these regions are more likely to be eruptive (Canfieldet al.1999). As the magnetic fields of the active regions are deep rooted in the Sun, the twist developed in the subphotospheric flux tube penetrates the photosphere and extends in to the corona. Thus, it is essentially favourable for the subphotospheric twist to unwind the twist and transmit it through the photosphere to the corona. Therefore, it becomes essential to make complete observational descriptions of a flare from the magnetic field changes that are taking place in different atmospheric levels of the Sun, to pin down the energy storage and conversion process that trigger the flare phenomena.

On the Configuration of the Magnetic Field of β CrB

1976 ◽  
Vol 32 ◽  
pp. 613-622
Author(s):  
I.A. Aslanov ◽  
Yu.S. Rustamov
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Radial Velocity ◽  
Magnetic Field Strength ◽  
Complex Shape ◽  
Rotation Period ◽  
Field Variation ◽  
Magnetic Field Variation ◽  
Secular Variations ◽  
The Magnetic Field

SummaryMeasurements of the radial velocities and magnetic field strength of β CrB were carried out. It is shown that there is a variability with the rotation period different for various elements. The curve of the magnetic field variation measured from lines of 5 different elements: FeI, CrI, CrII, TiII, ScII and CaI has a complex shape specific for each element. This may be due to the presence of magnetic spots on the stellar surface. A comparison with the radial velocity curves suggests the presence of a least 4 spots of Ti and Cr coinciding with magnetic spots. A change of the magnetic field with optical depth is shown. The curve of the Heffvariation with the rotation period is given. A possibility of secular variations of the magnetic field is shown.

Materials for Electron Beam Information Storage

1969 ◽  
Vol 27 ◽  
pp. 152-153 ◽  
Author(s):  
D. E. Speliotis
Keyword(s):  
Magnetic Field ◽  
Electron Beam ◽  
Recent Literature ◽  
Electron Beams ◽  
Information Storage ◽  
The Subject ◽  
The Magnetic Field

The interaction of electron beams with a large variety of materials for information storage has been the subject of numerous proposals and studies in the recent literature. The materials range from photographic to thermoplastic and magnetic, and the interactions with the electron beam for writing and reading the information utilize the energy, or the current, or even the magnetic field associated with the electron beam.

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