arXiv subjects
Publications and source records attributed to Guo-Qiang Zhu.
In this paper, the off-diagonal geometric phase of thermal state in hydrogen atom under the effects of external magnetic field is considered. Increasing temperature tends to suppress the off-diagonal geometric phase, including 1-order and 2-order cases. On the other hand, the relationship between the geometric phase and external magnetic field is discussed.
The geometric phase of a bi-particle model is discussed. For different initial states, especially when the initial state is pure or mixed, the geometric phase will show different properties. The relationship between the geometric phase and the entanglement or mixedness of the initial state is considered.
By using the partial transpose and realignment method,we study the time evolution of the bound entanglement under the bilinear-biquadratic Hamiltonian. For the initial Horodecki's bound entangled state, it keeps bound entangled for some time, while for the initial bound entangled states constructed from the unextendable product basis, they become free once the time evolution begins. The time evolution provides a new way to construct bound entangled states, and also gives a method to free bound entanglement.
In this paper, the geometric phase of thermal state in hydrogen atom under the effects of external magnetic field is considered. Especially the effects of the temperature upon the geometric phase is discussed. Also we discuss the time evolution of entanglement of the system. They show some similar behaviors.
The concurrence vectors are proposed by employing the fundamental representation of $A_n$ Lie algebra, which provides a clear criterion to evaluate the entanglement of bipartite system of arbitrary dimension for both pure and mixed states. Accordingly, a state is separable if the norm of its concurrence vector vanishes. The state vectors related to SU(3) states and SO(3) states are discussed in detail. The sign situation of nonzero components of concurrence vectors of entangled bases presents a simple criterion to judge whether the whole Hilbert subspace spanned by those bases is entangled, or there exists entanglement edge. This is illustrated in terms of the concurrence surfaces of several concrete examples.
We study the ground-state entanglement and thermal entanglement in the hyperfine interaction of the lithium atom. We give the relationship between the entanglement and both temperature and external magnetic fields.
We study the entanglement feature of the ground state of a system composed of spin 1 and 1/2 parts. The concurrence vector is shown to be consistent with the measurement of von Neumann entropy for such system. In the light of the ground state degeneracy, we suggest a average concurrence to measure the entanglement of Hilbert subspace. The entanglement property of both a general superposition as well as the mixture of the degenerate ground states are discussed by means of average concurrence and the negativity respectively.