1,980 research outputs found
High-Q Gold and Silicon Nitride Bilayer Nanostrings
Low-mass, high-Q, silicon nitride nanostrings are at the cutting edge of
nanomechanical devices for sensing applications. Here we show that the addition
of a chemically functionalizable gold overlayer does not adversely affect the Q
of the fundamental out-of-plane mode. Instead the device retains its mechanical
responsiveness while gaining sensitivity to molecular bonding. Furthermore,
differences in thermal expansion within the bilayer give rise to internal
stresses that can be electrically controlled. In particular, an alternating
current excites resonant motion of the nanostring. This AC thermoelastic
actuation is simple, robust, and provides an integrated approach to sensor
actuation.Comment: 5 pages, 4 figures + supplementary materia
Particle number fluctuations in nuclear collisions within excluded volume hadron gas model
The multiplicity fluctuations are studied in the van der Waals excluded
volume hadron-resonance gas model. The calculations are done in the grand
canonical ensemble within the Boltzmann statistics approximation. The scaled
variances for positive, negative and all charged hadrons are calculated along
the chemical freeze-out line of nucleus-nucleus collisions at different
collision energies. The multiplicity fluctuations are found to be suppressed in
the van der Waals gas. The numerical calculations are presented for two values
of hard-core hadron radius, fm and 0.5 fm, as well as for the upper
limit of the excluded volume suppression effects.Comment: 19 pages, 4 figure
Phonon quantum nondemolition measurements in nonlinearly coupled optomechanical cavities
In the field of cavity optomechanics, proposals for quantum nondemolition (QND) measurements of phonon number provide a promising avenue by which one can study the quantum nature of nanoscale mechanical resonators. Here we investigate these QND measurements for an optomechanical system whereby quadratic coupling arises due to shared symmetries between a single optical resonance and a mechanical mode. We establish a relaxed limit on the amount of linear coupling that can exist in this type of system while still allowing for QND measurements of mechanical Fock states. The ability to perform optomechanical QND measurements of this nature would allow one to probe the decoherence of these mesoscopic states, providing an experimental test bed for quantum collapse theories
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