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We investigate how to protect the quantum coherence and quantum Fisher information for two superconducting flux qubits each locally interacting with its own finite-temperature environment (heat bath) with 1/f spectral density by making use of bang-bang pulses. It is shown that the quantum coherence and quantum Fisher information can be improved by applying a train of bang-bang pulses and protected more effectively with shorter interval pulses. In addition, we also explore the influence of bang-bang pulses on the transfer of quantum information between two flux qubits and heat baths by a witness of trace distance. It is found that the bang-bang pulses can suppress the effect of heat baths and slow down the exchange of the quantum information flows between two flux qubits and heat baths. [ABSTRACT FROM AUTHOR]

We investigate the dynamics of quantum coherence of a system consisting of two interacting atoms coupling with a common cavity which is filled with a nonlinear Kerr-like medium, in the presence of intrinsic decoherence. It is shown that the stationary quantum coherence can arise in the system as the time approach to infinite. In particular, the amount of stationary quantum coherence can be enhanced by adjusting the Kerr interaction and dipole-dipole interaction. Furthermore, we also explore the influence of Kerr interaction and dipole-dipole interaction on the transfer of quantum information by a witness of the trace distance and find that the transferred information and stationary quantum information can be controlled by the Kerr interaction and dipole-dipole interaction. [ABSTRACT FROM AUTHOR]

We investigate the dynamics of non-classical correlations(entanglement and quantum discord) of the system consisting of two non-interacting superconducting qubits coupling with a common data bus, where the system is driven by the dynamical decoupling pulses. It is found that the non-classical correlations between two superconducting qubits can be increased by appling a train of dynamical decoupling pulses. Furthermore, we also explore the influence of the dynamical decoupling pulses on the information flowing between superconducting qubits and data bus by making use of the trace distance. It is shown that the dynamical decoupling pulses can protect quantum information of two superconducting qubits and force information to flow back to the superconducting qubits from the data bus. [ABSTRACT FROM AUTHOR]

By making use of the trace distance as a measure we investigate the influence of classical driving fields on a open quantum system when the system and its environment are initially in a correlated state. It is shown that the amount of trace distance is sensitive to the classical driving fields which implies that the information flowing between open system and its environment can be controlled by the classical driving fields. Furthermore, we also explore the dependence of the trace distance on the initial parameters when the total system is considered in the thermal equilibrium state. We find that the trace distance on the coupling strength can be used to demonstrate the level crossing of the ground state of the system. In particular, the classical driving fields have significant effect on the level crossing of the ground state. [ABSTRACT FROM AUTHOR]

We investigate quantum Fisher information dynamics in two component Bose-Einstein condensate interacting spins with an external field. Approximate analytical expressions of quantum Fisher information is presented. Our analysis shows that quantum Fisher information is controlled by adjusting the strength of the external field and the total atomic number. It is shown that the maximal mean quantum Fisher information is occurred and the phase estimation is enhanced to the Heisenberg limit under some conditions. [ABSTRACT FROM AUTHOR]

To meet the requirement of high tracking angular accuracy for the acquisition, tracking, and pointing (ATP) subsystem of the free-space optical communication, and provide the basis for the further optical communication between maritime mobile platforms, the experimental system, which executing part for the fine tracking is voice coil motor with high frequency and good performance for error compensation, is established, and the whole system can be controlled by personal computer. A series of experiments has been done for the simulation target of different uniform speed, and the data of tracking error for fine tracking and coarse tracking are collected, analyzed and evaluateds separately, and the real-time optical power of communication laser is also collected. The result shows that standard deviation for ATP system tracking error increases with the increase of target speed, while the range of tracking error appears to be no order. Furthermore, communication link can be hold for a long time. [ABSTRACT FROM AUTHOR]