2,161 research outputs found
Dynamics of quantum coherence in Bell-diagonal states under Markovian channels
We study the curves of coherence for the Bell-diagonal states including
-norm of coherence and relative entropy of coherence under the Markovian
channels in the first subsystem once. For a special Bell-diagonal state under
bit-phase flip channel, we find frozen coherence under norm occurs, but
relative entropy of coherence decrease. It illustrates that the occurrence of
frozen coherence depends on the type of the measure of coherence. We study the
coherence evolution of Bell-diagonal states under Markovian channels in the
first subsystem times and find coherence under depolarizing channel
decreases initially then increases for small and tend to zero for large
. We discuss the dynamics of coherence of the Bell-diagonal state under two
independent same type local Markovian channels. We depict the dynamic behaviors
of relative entropy of coherence for Bell-diagonal state under the bi-side
different Markovian channel. We depict the dynamic behaviors of relative
entropy of coherence for Bell-diagonal state under the bi-side different
Markovian channel.Comment: 13 pages, 17 figure
Trajectory Design of Laser-Powered Multi-Drone Enabled Data Collection System for Smart Cities
This paper considers a multi-drone enabled data collection system for smart cities, where there are two kinds of drones, i.e., Low Altitude Platforms (LAPs) and a High Altitude Platform (HAP). In the proposed system, the LAPs perform data collection tasks for smart cities and the solar-powered HAP provides energy to the LAPs using wireless laser beams. We aim to minimize the total laser charging energy of the HAP, by jointly optimizing the LAPs’ trajectory and the laser charging duration for each LAP, subject to the energy capacity constraints of the LAPs. This problem is formulated as a mixed-integer and non-convex Drones Traveling Problem (DTP), which is a combinatorial optimization problem and NP-hard. We propose an efficient and novel search algorithm named DronesTraveling Algorithm (DTA) to obtain a near-optimal solution. Simulation results show that DTA can deal with the large scale DTP (i.e., more than 400 data collection points) efficiently. Moreover, the DTA only uses 5 iterations to obtain the nearoptimal solution whereas the normal Genetic Algorithm needs nearly 10000 iterations and still fails to obtain an acceptable solution
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