An Interpretation of Flat Density Cores of Clusters of Galaxies by Degeneracy Pressure of Fermionic Dark Matter: A Case Study of Abell 1689

Flat density cores have been obtained for a limited number of clusters of galaxies by strong gravitational lensing. This paper explores the possibility that the degeneracy pressure of fermionic dark matter accounts for the flat top density profiles. This is a case study of A1689 for which the density profile has been obtained from the inner region out to 1Mpc by the combination of strong and weak lensing. In the case that the dark matter consists of the mixture of degenerate relic neutrinos and collisionless cold dark matter particles, the acceptable mass range for relic neutrinos is between 1 and 2 eV, if the ratio of the two kinds of dark matter particles is fixed to its cosmic value.Comment: Accepted for Publication in ApJ. Companion paper to astro-ph/060709

Boosting computational power through spatial multiplexing in quantum reservoir computing

Quantum reservoir computing provides a framework for exploiting the natural dynamics of quantum systems as a computational resource. It can implement real-time signal processing and solve temporal machine learning problems in general, which requires memory and nonlinear mapping of the recent input stream using the quantum dynamics in computational supremacy region, where the classical simulation of the system is intractable. A nuclear magnetic resonance spin-ensemble system is one of the realistic candidates for such physical implementations, which is currently available in laboratories. In this paper, considering these realistic experimental constraints for implementing the framework, we introduce a scheme, which we call a spatial multiplexing technique, to effectively boost the computational power of the platform. This technique exploits disjoint dynamics, which originate from multiple different quantum systems driven by common input streams in parallel. Accordingly, unlike designing a single large quantum system to increase the number of qubits for computational nodes, it is possible to prepare a huge number of qubits from multiple but small quantum systems, which are operationally easy to handle in laboratory experiments. We numerically demonstrate the effectiveness of the technique using several benchmark tasks and quantitatively investigate its specifications, range of validity, and limitations in detail.Comment: 15 page

Nanofixation with Low Melting Metal Based on Nanorobotic Manipulation

IEEE-NANO 200

Nonlinear Pressure Dependence of the Superconducting Transition Temperature of Copper Sulfide CuS

The superconducting transition temperatures of copper sulfide CuS are measured as a function of hydrostatic pressure up to about 9 katm by an ice bomb technique. The superconducting transition is detected with the ac Hartshorn mutual inductance bridge. In contrast to ordinary superconductors the curve of the shift of the transition temperature with increasing pressure decrease nonlinearly with downward curvature over the whole range of applied pressures and its slope changes discontinuously at about 3.5 katm. The maximum peak of the imaginary part of the ac susceptibility vanishes under pressurs above about 1.6 katm. It is discussed that the observed unusual behaviour of the transition temperature is probably attributed to a change of the Fermi surface of the type proposed by Lifshitz