arXiv subjects

Y. Q. Guo

Publications and source records attributed to Y. Q. Guo.

95 records · Page 6Linked to original sources

arXiv2005

The dissipation of the system and the atom in two-photon Jaynes-Cummings model with degenerate atomic levels

The method of perturbative expansion of master equation is employed to study the dissipative properties of system and of atom in the two-photon Jaynes-Cummings model (JCM) with degenerate atomic levels. The numerical results show that the degeneracy of atomic levels prolongs the period of entanglement between the atom and the field. The asymptotic value of atomic linear entropy is apparently increased by the degeneration. The amplitude of local entanglement and disentanglement is suppressed. The better the initial coherence property of the degenerate atom, the larger the coherence loss.

quant-ph↗

arXiv2005

Entangling Two-Atom Through Cooperative Interaction Under Stimulated Emission

We discuss the generation of two-atom entanglement inside a resonant microcavity under stimulated emission (STE) interaction. The amount of entanglement is shown based on different atomic initial state. For each kind of intial state, we obtain the entanglement period and the entanglement critical point, which are found to deeply depend on driving field density. In case of atomic state $| ee >$, the entanglement can be induced due to STE. In case of atomic state $| eg >$, there is a competition between driving field indued entanglement and STE induced entanglement. When two atoms are initially in $| gg >$, we can find a lumbar region where STE increases the amount and period of entanglement.

quant-ph↗

arXiv2005

Physical properties, strontium ordering and structural modulation in layered hexagonal Sr0.35CoO2

Layered Sr0.35CoO2 has been synthesized by means of an ion exchange reaction from Na0.7CoO2. Resistivity measurements show that this material can be either metallic or semiconducting depending on the annealing conditions. Magnetic susceptibility, following the Curie-Weiss law, increases with lowering temperature and shows a small anomalous kink at around 30 K. Transmission-electron-microscopy observations reveal the presence of two superstructures arising respectively from the intercalated Sr-ordering (a compositional modulation) with q1 = a* / 3 + b* / 3 and a periodic structural distortion (a transverse structural modulation) with q2 = a* / 2.

cond-mat.str-el↗

arXiv2003

Entangled two atoms through different couplings and the thermal noise

The entanglement of two atoms is studied when the two atoms are coupled to a single-mode thermal field with different couplings. The different couplings of two atoms are in favor of entanglement preparation: it not only makes the case of absence entanglement with same coupling appear entanglement, but also enhances the entanglement with the increasing of the relative difference of two couplings. We also show that the diversity of coupling can improved the critical temperature. If the optical cavity is leaky during the time evolution, the dissipative thermal environment is benefit to produce the entanglement.

quant-ph↗

arXiv2003

Enhanced the thermal Entanglement in Anisotropy XYZ Heisenberg Chain

The thermal entanglement in Heisenberg $XYZ$ chain is investigated in the presence of external magnetic field $B$. In the two-qubit system, the critical magnetic field $B_c$ is increased because of introducing the interaction of the z-component of two neighboring spins $J_z$. This interaction not only improves the critical temperature $T_c,$ but also enhances the entanglement for particular fixed $B$. We also analyze the pairwise entanglement between nearest neighbors in three qubits. The pairwise entanglement, for a fixed $T$, can be strong by controlling $B$ and $J_z$. PACS: 03.65. Ud, 03.67. -a, 75.10. Jm

quant-ph↗