共查询到20条相似文献,搜索用时 343 毫秒
1.
Thermal entanglement of a two-qutrit Ising system in the presence of an external homogeneous magnetic field and Dzialoshinski-Moriya (DM) interaction is investigated. Influences of magnetic field, temperature, and DM interaction on the entanglement have been characterized in terms of negativity for a wide range of parameters. The cases of parallel, antiparallel and transverse magnetic fields are considered. Results of detailed numerical calculations are explained using the analytically determined ground and excited states of the system. It is shown that at a given temperature, control of entanglement can be optimized by utilizing competing effects of the magnetic field and the DM interaction. 相似文献
2.
M. Amniat-Talab H. Rangani Jahromi S. Golkar 《International Journal of Theoretical Physics》2013,52(1):163-177
We show that the entanglement (as quantified by the concurrence) and Berry phases of the adiabatic quantum states vanish for a two spin-1/2 system with Dzyaloshinski-Moriya (DM) interaction, while one of the spins is driven by a time-varing rotating magnetic field and the other one is coupled with a strong static magnetic field. The system is described by the Heisenberg XX model and the static field is in the direction of the rotation axis. We also investigate that how the concurrence and Berry phases depend on the DM interaction, coupling coefficient and the static magnetic field. In addition, we show that reversing the sign of the static magnetic field can cause exchange of the Berry phases and entanglement between the adiabatic states. Finally it is shown that each energy level approach causes jumps or cusp-like behaviour in the Berry phases and the concurrences. 相似文献
3.
K.Yu. Bliokh 《Physics letters. A》2008,372(3):204-209
We examine both quantum and classical versions of the problem of spin evolution in a slowly varying magnetic field. Main attention is given to the first- and second-order adiabatic corrections in the case of in-plane variations of the magnetic field. While the first-order correction relates to the usual adiabatic Berry phase and Coriolis-type lateral deflection of the spin, the second-order correction is shown to be responsible for the next-order geometric phase and in-plain deflection. A comparison between different approaches, including the exact (non-adiabatic) geometric phase, is presented. 相似文献
4.
Xiao San Ma 《Optics Communications》2008,281(3):484-488
The effect of Dzialoshinski-Moriya (DM) interaction on thermal entanglement of a two-qutrit XX spin chain in a homogenous magnetic field is investigated. Our results imply that DM interaction and the magnetic field play competing roles in enhancing thermal entanglement. 相似文献
5.
Entanglement in One-Dimensional Random XY Spin Chain with Dzyaloshinskii--Moriya Interaction 下载免费PDF全文
The impurities of exchange couplings, external magnetic fields and Dzyaloshinskii-Moriya (DM) interaction considered as Gaussian distribution, and the entanglement in one-dimensional random XY spin systems is investigated by the method of solving the different spin-spin correlation functions and the average magnetization per spin. The entanglement dynamics at central locations of ferromagnetic and antiferromagnetic chains have been studied by varying the three impurities and the strength of DM interaction. (i) For the ferromagnetic spin chain, the weak DM interaction can improve the amount of entanglement to a large value, and the impurities have the opposite effect on the entanglement below and above critical DM interaction. (ii) For the antiferromagnetic spin chain, DM interaction can enhance the entanglement to a steady value. Our results imply that DM interaction strength, the impurity and exchange couplings (or magnetic field) play competing roles in enhancing quantum entanglement. 相似文献
6.
M.-M. He G. Chen J.-Q. Liang 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,44(3):581-583
In this paper we investigate the Berry phase in Tavis-Cummings model in the
rotating wave approximation. The dipole-dipole interaction between the atoms
is considered. The eigenfunctions of the system are obtained and thus the
Berry phase is evaluated explicitly in terms of the introduction of the
phase shift. It is shown that the Berry phase can be easily controlled by
the atom-cavity coupling strength, the cavity frequency detuning, which can
be important in applications in geometric quantum computing. 相似文献
7.
Shot noise for entangled and spin-polarized states in a four-probe geometric setup has been studied by adding two rotating magnetic fields in an incoming channel. Our results show that the noise power oscillates as the magnetic fields vary. The singlet, entangled triplet and polarized states can be distinguished by adjusting the magnetic fields. The Berry phase can be derived by measuring the shot noise power. 相似文献
8.
We propose a method for analyzing Berry phase for a multi-qubit system of superconducting charge qubits interacting with a microwave field. By suitably choosing the system parameters and precisely controlling the dynamics, novel connection found between the Berry phase and entanglement creations. 相似文献
9.
P. Gosselin A. Bérard H. Mohrbach 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,58(2):137-148
It has been recently found that the equations of motion of several
semiclassical systems must take into account terms arising from Berry phases
contributions. Those terms are responsible for the spin Hall effect in
semiconductor as well as the Magnus effect of light propagating in
inhomogeneous media. Intensive ongoing research on this subject seems to
indicate that a broad class of quantum systems may be affected by Berry
phase terms. It is therefore important to find a general procedure allowing
for the determination of semiclassical Hamiltonian with Berry Phase
corrections. This article presents a general diagonalization method at order
ħ for a large class of quantum Hamiltonians directly inducing Berry
phase corrections. As a consequence, Berry phase terms on both coordinates
and momentum operators naturally arise during the diagonalization procedure.
This leads to new equations of motion for a wide class of semiclassical
system. As physical applications we consider here a Dirac particle in an
electromagnetic or static gravitational field, and the propagation of a
Bloch electrons in an external electromagnetic field. 相似文献
10.
Sangchul Oh 《Physics letters. A》2009,373(6):644-647
It is shown that geometric phases and entanglement may fail to detect level crossings for two qubits with XY interaction. The rotating magnetic field produces a magnetic monopole sphere like conducting spheres in that only a ground state evolving adiabatically outside the sphere acquires a geometric phase. 相似文献
11.
We investigate the entanglement dynamics and Bell violation of three-qubit quantum states under an environment consisting of an XY spin chain with Dzyaloshinski–Moriya (DM) interaction. From the results, we find that the entanglement dynamics depends not only on the DM interaction, the magnetic field, and the anisotropy parameter but also on the number of the freedom degrees of the environment. The decoherence-free subspaces of our model have been identified and the Bell violation of quantum states is also discussed. 相似文献
12.
The Berry phase in a bipartite system described by the XXZ model is studied in this Letter. We calculate the Berry phase acquired by the bipartite system as well as the geometric phase gained by each subsystem. The results show that as the coupling constants tend to infinity all geometric phases go to zero, this confirms the prediction given by us previously [X.X. Yi, L.C. Wang, T.Y. Zheng, Phys. Rev. Lett. 92 (2004) 150406] for bipartite systems with a specific subsystem–subsystem coupling. 相似文献
13.
G. De Chiara A. Łoziński G. M. Palma 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,41(1):179-183
The evolution of a two level system with a slowly varying Hamiltonian, modeled as a spin 1/2 in a slowly varying magnetic
field, and interacting with a quantum environment, modeled as a bath of harmonic oscillators is analyzed using a quantum Langevin
approach. This allows to easily obtain the dissipation time and the correction to the Berry phase in the case of an adiabatic
cyclic evolution. 相似文献
14.
The Berry phase in a composite system induced by the time-dependent interaction is discussed. We choose two coupled spin-1/2 systems as the composite system: one of the subsystems is subjected to a static magnetic field, and the coupling parameters between two spins are controllable in time. We show that the time-dependent interaction can induce the Berry phase in a similar way as that a spin-1/2 system (qubit) is driven by an effective time-dependent magnetic field. Furthermore, using two consecutive cycles with opposite directions of both the static magnetic field as well as opposite signs of the coupling parameters, a nontrivial two-qubit unitary transformation purely based on Berry phases can be constructed. 相似文献
15.
M. P. Trushin A. L. Chudnovskiy 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,52(4):547-555
We have found a manifestation of spin-orbit Berry phase in the conductance
of a mesoscopic loop with Rashba spin-orbit coupling placed in an external magnetic field
perpendicular to the loop plane.
In detail, the transmission probabilities for a straight quantum wire
and for a quantum loop made of the same wire have been calculated and
compared with each other.
The difference between them has been investigated and identified with
a manifestation of spin-orbit Berry phase.
The non-adiabaticity effects at small radii of the loop have been found as well. 相似文献
16.
We studied the effects of Dzyaloshinski-Moriya (DM) anisoyropic antisymmetric interaction on entanglement and teleportation in a two-qubit Heisenberg chain with intrinsic decoherence taken into account. The main result is the systematic analysis of the negativity and fully entangled fraction’s evolution as a function of DM interaction D and time t. The contrast between the case of the maximally entangled initial state and unentangled ones is presented. 相似文献
17.
Josevi de S. Carvalho E. Passos Claudio Furtado Fernando Moraes 《The European Physical Journal C - Particles and Fields》2008,57(4):817-822
The relativistic quantum dynamics of a spinorial quantum particle in the presence of a chiral conical background is investigated.
We study the gravitational Berry geometric quantum phase acquired by a spin 1/2 particle in the chiral cosmic string spacetime.
We obtain the result that this phase depends on the global features of this spacetime. We also consider the case that a string
possesses an internal magnetic flux and obtain the geometric quantum phase in this case. The spacetime of multiple chiral
cosmic strings is considered and the relativistic Berry quantum phase is also obtained. 相似文献
18.
Adiabatic approximation for quantum evolution is investigated addressing its dependence on the Berry connections that are functions of a slowly-varying parameter R . When the Berry connections have singularities of type 1/Rσ with σ<1, the adiabatic fidelity converges to unit according to a power-law; When the singularity index σ becomes larger than one, adiabatic approximation breaks down. Two-level models are used to substantiate our theory. 相似文献
19.
De-Hone Lin 《Annals of Physics》2008,323(2):317-336
The solution of D-dimensional Coulomb system is solved in momentum space by path integral. From which the topological effect of a magnetic flux in the system is given. It is revealed that the flux effect represented by the two-dimensional field of Aharonov-Bohm covers any space-dimensions. 相似文献
20.
In this paper, the entanglement in a mixed-spin (1/2, 3/2) Heisenberg XXZ model with Dzyaloshinskii-Moriya (DM) interaction in an inhomogeneous external magnetic field is studied. We not only calculate the ground-state entanglement but also investigate the behaviors of quantum phase transition following the changes of DM interaction and nonuniform magnetic field. More importantly, we note that the DM interaction improves the critical magnetic field B c , the critical temperature T c and broadens the region of entanglement. 相似文献