6 research outputs found
Quantum statistical effects in nano-oscillator arrays
We have theoretically predicted the density of states(DOS), the low
temperature specific heat, and Brillouin scattering spectra of a large, free
standing array of coupled nano-oscillators. We have found significant gaps in
the DOS of 2D elastic systems, and predict the average DOS to be nearly
independent of frequency over a broad band f < 50GHz. At low temperatures, the
measurements probe the quantum statistics obeyed by rigid body modes of the
array and, thus, could be used to verify the quantization of the associated
energy levels. These states, in turn, involve center-of mass motion of large
numbers of atoms, N > 1.e14, and therefore such observations would extend the
domain in which quantum mechanics has been experimentally tested. We have found
the required measurement capability to carry out this investigation to be
within reach of current technology.Comment: 1 tex file, 3 figures, 1 bbl fil
Relativistic and Binding Energy Corrections to Direct Photon Production In Upsilon Decay
A systematic gauge-invariant method is used to calculate the rate for an
upsilon meson to decay inclusively into a prompt photon. An expansion is made
in the quark relative velocity v, which is a small natural parameter for heavy
quark systems. Inclusion of these O(v^2) corrections tends to increase the
photon rate in the middle z range and to lower it for larger z, a feature
supported by the data.Comment: 13 pages, LateX, One figure (to be published in Phys. Rev. D, Sept.
1, 1996
DETC2005-84855 VIBRATION LOCALIZATION IN NEAR-PERIODIC COUPLED TWO-DIMENSIONAL RESONATOR ARRAYS
ABSTRACT The effects of small deviations from periodicity on the vibration behavior of coupled arrays of mechanical resonators are investigated, and the consequences for energy propagation across such arrays are described. Existing localization theory is applied to demonstrate that one-dimensional arrays designed as bandpass filters are particularly sensitive to aperiodicity when narrow passband requirements dictate weak interresonator coupling. A novel two-dimensional array of resonators is proposed that is less sensitive to disorder than one-dimensional arrays, improving filter performance without the need for improved manufacturing tolerances. Numerical simulations of a simple model are employed to demonstrate the effects of disorder on one-and two-dimensional arrays, and a case study design is discussed that includes statistical investigation using finite-element analysis and experimental measurements of a prototype two-dimensional array
Acoustic cavities in 2D heterostructures
Two-dimensional (2D) materials offer unique opportunities in engineering the ultrafast spatiotemporal response of composite nanomechanical structures. In this work, we report on high frequency, high quality factor (Q) 2D acoustic cavities operating in the 50–600 GHz frequency (f) range with f × Q up to 1 × 10(14). Monolayer steps and material interfaces expand cavity functionality, as demonstrated by building adjacent cavities that are isolated or strongly-coupled, as well as a frequency comb generator in MoS(2)/h-BN systems. Energy dissipation measurements in 2D cavities are compared with attenuation derived from phonon-phonon scattering rates calculated using a fully microscopic ab initio approach. Phonon lifetime calculations extended to low frequencies (<1 THz) and combined with sound propagation analysis in ultrathin plates provide a framework for designing acoustic cavities that approach their fundamental performance limit. These results provide a pathway for developing platforms employing phonon-based signal processing and for exploring the quantum nature of phonons