Showing papers by "Jian Chen published in 2005"
TL;DR: In this article, a model analysis of the current-voltage curve of YBa2Cu3O7−δ grain boundary Josephson junctions coupled to a GHz signal is presented.
Abstract: High Tc Josephson junctions have IcRn products as large as a few mV at liquid helium temperature, and hence, the frequency normalized by IcRn∕Φ0 becomes on the order of 10−3 for a gigahertz (GHz) microwave signal. (Here, Ic, Rn, and Φ0 are the critical current, the normal resistance, and a flux quantum, respectively.) It is well known that a microwave-current-driven Josephson junction does not exhibit clear Shapiro steps under such low frequency conditions. Instead of Shapiro steps, however, we often observe a current-step-like structure in the current–voltage curve of YBa2Cu3O7−δ grain boundary Josephson junctions coupled to a GHz signal. In this article, we present a model analysis for such current-step-like structures. Two types of device models are employed: a simple resistively and capacitively shunted junction model and a rf-field-driven two-junction superconducting quantum interference device model. Numerical results of the latter model agree with the experimental results, which indicates that the ...
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TL;DR: In this paper, it was shown that two two-level atoms coupled simultaneously with a third dissipated atom would end up with entangled states, and the dissipation of the third atom is supposed to come from its coupling to noises with adjustable intensity.
Abstract: We show that two two-level atoms coupled simultaneously with a third dissipated atom would end up with entangled states The dissipation of the third atom is supposed to come from its coupling to noises with adjustable intensity Two kinds of noise, white noise and squeezing white noise, are identified to possess the ability to help preparation of entanglement We confirm that the entanglement is maximized for intermediate values of the noise intensity with all atoms in the ground state, while it is a monotonic function of the spontaneous rates
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TL;DR: In this paper, a spin-half approximation method for two-component condensation in double-wells is proposed to discuss the quantum entanglement of two components, which is valid under stationary tunneling effect for odd particle number of each component.
Abstract: We propose a spin-half approximation method for two-component condensation in double wells to discuss the quantum entanglement of two components. This approximation is presented to be valid under stationary tunneling effect for odd particle number of each component. The evolution of the entanglement is found to be affected by the particle number both quantitatively and qualitatively. In detail, the maximal entanglement are shown to be hyperbolic like with respect to tunneling rate and time. To successively obtain large and long time sustained entanglement, the particle number should not be large.