87 research outputs found
Electromechanically induced absorption in a circuit nano-electromechanical system
A detailed analysis of electromechanically induced absorption (EMIA) in a
circuit nano-electromechanical hybrid system consisting of a superconducting
microwave resonator coupled to a nanomechanical beam is presented. By
performing two-tone spectroscopy experiments we have studied EMIA as a function
of the drive power over a wide range of drive and probe tone detunings. We find
good quantitative agreement between experiment and theoretical modeling based
on the Hamiltonian formulation of a generic electromechanical system. We show
that the absorption of microwave signals in an extremely narrow frequency band
(\Delta\omega/2\pi <5 Hz) around the cavity resonance of about 6 GHz can be
adjusted over a range of more than 25 dB on varying the drive tone power by a
factor of two. Possible applications of this phenomenon include notch filters
to cut out extremely narrow frequency bands (< Hz) of a much broader band of
the order of MHz defined by the resonance width of the microwave cavity. The
amount of absorption as well as the filtered frequency is tunable over the full
width of the microwave resonance by adjusting the power and frequency of the
drive field. At high drive power we observe parametric microwave amplification
with the nanomechanical resonator. Due to the very low loss rate of the
nanomechanical beam the drive power range for parametric amplification is
narrow, since the beam rapidly starts to perform self-oscillations.Comment: 16 pages, 5 figure
Determination of effective mechanical properties of a double-layer beam by means of a nano-electromechanical transducer
We investigate the mechanical properties of a doubly-clamped, double-layer
nanobeam embedded into an electromechanical system. The nanobeam consists of a
highly pre-stressed silicon nitride and a superconducting niobium layer. By
measuring the mechanical displacement spectral density both in the linear and
the nonlinear Duffing regime, we determine the pre-stress and the effective
Young's modulus of the nanobeam. An analytical double-layer model
quantitatively corroborates the measured values. This suggests that this model
can be used to design mechanical multilayer systems for electro- and
optomechanical devices, including materials controllable by external parameters
such as piezoelectric, magnetrostrictive, or in more general multiferroic
materials.Comment: 4 pages, 4 figures, 1 supplemental materia
Secularisation and the rise of immigrant religions :the case of the Netherlands
Europe and the United States are very different as far as the significance of religion is concerned, both in the private and the public sphere. Whereas autochthon Europe is secularising to a great extent and any growth of religiousness is mainly a matter of immigrants, the United States is the scene of a vivid market of numerous churches, congregations and sects culminating in a high rate of people that belong to a church or religious community and that believe in God. The aim of this paper is to explain this gap between Europe and the United States on the basis of social science theory and theoretical insights derived from (historical) political and cultural geography. It is argued that a different kind of historical political territorialisation (from below in the US versus from above in Europe) in combination with culturally selective settlement (US) is at the centre of the explanation16328
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