2,517 research outputs found
Robust stabilization of nonlinear discrete-time systems based on T-S model
A robust stabilization problem is considered about nonlinear discrete-time system based on T-S fuzzy model. In order to represent the system exactly, the parametric uncertainty is employed to the T-S model. A necessary and sufficient condition for the existence of such controllers through Lyapunov theorem is given. And it is further shown that this condition is equivalent to the solvability of a certain linear matrix inequality. An illustrative example of truck-trailer shows the feasibility of the proposed method
Time-resolved boson sampling with photons of different colors
Interference of multiple photons via a linear-optical network has profound
applications for quantum foundation, quantum metrology and quantum computation.
Particularly, a boson sampling experiment with a moderate number of photons
becomes intractable even for the most powerful classical computers, and will
lead to "quantum supremacy". Scaling up from small-scale experiments requires
highly indistinguishable single photons, which may be prohibited for many
physical systems. Here we experimentally demonstrate a time-resolved version of
boson sampling by using photons not overlapping in their frequency spectra from
three atomic-ensemble quantum memories. Time-resolved measurement enables us to
observe nonclassical multiphoton correlation landscapes. An average fidelity
over several interferometer configurations is measured to be 0.936(13), which
is mainly limited by high-order events. Symmetries in the landscapes are
identified to reflect symmetries of the optical network. Our work thus provides
a route towards quantum supremacy with distinguishable photons.Comment: 5 pages, 3 figures, 1 tabl
Correlation between mobile phone addiction tendency and its related risk factor among Chinese college students: A cross-sectional study
Purpose: Mobile phone addiction prevalence is a global concern which has attracted great attention. It is now considered that excessive mobile phone usage is associated with potentially harmful and/or disturbing behaviors. The present study was aimed at exploring the current situation and related factors of mobile phone addiction tendency and providing a scientific suggestion for its prevention among college students.
Methods: A cross-sectional study was applied for stratified cluster random sampling among college students, including five survey tools: the basic information questionnaire, UCLA loneliness scale, college students’ interpersonal comprehensive diagnostic scale, the Pittsburgh sleep quality index scale and mobile phone addiction tendency scale (MPATS). SPSS v 17.0 statistical tool was applied to analyze data from the survey.
Results: A total of 760 questionnaires were administered of which 735 questionnaires were retrieved and the valid questionnaires were 730. Classification of mobile phone addiction tendency has statistical significance with grade. Also, classification of loneliness has statistical significance with major, grade and home address. Furthermore, classification of interpersonal relationship has statistical significance with romance status and grade. Additionally, classification of MPATS was positively correlated with classification of UCLA loneliness scale, Pittsburgh sleep quality index scale and interpersonal relationship scale. Interpersonal relationship, sleep quality, and loneliness were linearly correlated with mobile phone addiction tendency.
Conclusion: Grade, interpersonal relationship, sleep quality and loneliness were positively correlated with mobile phone addiction tendency, which are the associated risk factors. Therefore, concerns and interventions are required to decrease the risk factor for the sake of college students’ health
Sequential generation of multiphoton entanglement with a Rydberg superatom
Multiqubit entanglement is an indispensable resource for quantum information
science. In particular, the entanglement of photons is of conceptual interest
due to its implications in measurement-based quantum computing, communication,
and metrology. The traditional way of spontaneous parametric down-conversion
already demonstrates entanglement of up to a dozen photons but is hindered by
its probabilistic nature. Here, we experimentally demonstrate an efficient
approach for multi-photon generation with a Rydberg superatom, a mesoscopic
atomic ensemble under Rydberg blockade. Using it as an efficient single-photon
interface, we iterate the photon creation process that gives rise to a train of
temporal photonic modes entangled in photon number degree. We detect the
multiphoton entanglement via converting the photon number degree to a time-bin
degree. Photon correlations verify entanglement up to 12 modes. The efficiency
scaling factor for adding one photon is 0.27, surpassing previous results, and
can be increased significantly without fundamental limitations.Comment: 11 pages, 9 figure
Observation of prolonged coherence time of the collective spin wave of atomic ensemble in a paraffin coated Rb vapor cell
We report a prolonged coherence time of the collective spin wave of a thermal
87Rb atomic ensemble in a paraffin coated cell. The spin wave is prepared
through a stimulated Raman Process. The long coherence time time is achieved by
prolonging the lifetime of the spins with paraffin coating and minimize
dephasing with optimal experimental configuration. The observation of the long
time delayed-stimulated Stokes signal in the writing process suggests the
prolonged lifetime of the prepared spins; a direct measurement of the decay of
anti-Stokes signal in the reading process shows the coherence time is up to 300
us after minimizing dephasing. This is one hundred times longer than the
reported coherence time in the similar experiments in thermal atomic ensembles
based on the Duan-Lukin-Cirac-Zoller (DLCZ) and its improved protocols. This
prolonged coherence time sets the upper limit of the memory time in quantum
repeaters based on such protocols, which is crucial for the realization of
long-distance quantum communication. The previous reported fluorescence
background in the writing process due to collision in a sample cell with buffer
gas is also reduced in a cell without buffer gas.Comment: 4 pages, 4 figure
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