1,418 research outputs found
Minimization of phonon-tunneling dissipation in mechanical resonators
Micro- and nanoscale mechanical resonators have recently emerged as
ubiquitous devices for use in advanced technological applications, for example
in mobile communications and inertial sensors, and as novel tools for
fundamental scientific endeavors. Their performance is in many cases limited by
the deleterious effects of mechanical damping. Here, we report a significant
advancement towards understanding and controlling support-induced losses in
generic mechanical resonators. We begin by introducing an efficient numerical
solver, based on the "phonon-tunneling" approach, capable of predicting the
design-limited damping of high-quality mechanical resonators. Further, through
careful device engineering, we isolate support-induced losses and perform the
first rigorous experimental test of the strong geometric dependence of this
loss mechanism. Our results are in excellent agreement with theory,
demonstrating the predictive power of our approach. In combination with recent
progress on complementary dissipation mechanisms, our phonon-tunneling solver
represents a major step towards accurate prediction of the mechanical quality
factor.Comment: 12 pages, 4 figure
Influence of diffraction on the spectrum and wavefunctions of an open system
In this paper, we demonstrate the existence and significance of diffractive
orbits in an open microwave billiard, both experimentally and theoretically.
Orbits that diffract off of a sharp edge of the system are found to have a
strong influence on the transmission spectrum of the system, especially in the
regime where there are no stable classical orbits. On resonance, the
wavefunctions are influenced by both classical and diffractive orbits. Off
resonance, the wavefunctions are determined by the constructive interference of
multiple transient, nonperiodic orbits. Experimental, numerical, and
semiclassical results are presented.Comment: 27 pages, 29 figures, and 3 tables. Submitted to Physical Review E. A
copy with higher resolution figures is available at
http://monsoon.harvard.edu/~hersch/papers.htm
First International Conference on Laboratory Research for Planetary Atmospheres
Proceedings of the First International Conference on Laboratory Research for Planetary Atmospheres are presented. The covered areas of research include: photon spectroscopy, chemical kinetics, thermodynamics, and charged particle interactions. This report contains the 12 invited papers, 27 contributed poster papers, and 5 plenary review papers presented at the conference. A list of attendees and a reprint of the Report of the Subgroup on Strategies for Planetary Atmospheres Exploration (SPASE) are provided in two appendices
Quantitative modeling of superconducting planar resonators with improved field homogeneity for electron spin resonance
We present three designs for planar superconducting microwave resonators for
electron spin resonance (ESR) experiments. We implement finite element
simulations to calculate the resonance frequency and quality factors as well as
the three-dimensional microwave magnetic field distribution of the resonators.
One particular resonator design offers an increased homogeneity of the
microwave magnetic field while the other two show a better confinement of the
mode volume. We extend our model simulations to calculate the collective
coupling rate between a spin ensemble and a microwave resonator in the presence
of an inhomogeneous magnetic resonator field. Continuous-wave ESR experiments
of phosphorus donors in Si demonstrate the feasibility of our
resonators for magnetic resonance experiments. We extract the collective
coupling rate and find a good agreement with our simulation results,
corroborating our model approach. Finally, we discuss specific application
cases for the different resonator designs
Generation of a wave packet tailored to efficient free space excitation of a single atom
We demonstrate the generation of an optical dipole wave suitable for the
process of efficiently coupling single quanta of light and matter in free
space. We employ a parabolic mirror for the conversion of a transverse beam
mode to a focused dipole wave and show the required spatial and temporal
shaping of the mode incident onto the mirror. The results include a proof of
principle correction of the parabolic mirror's aberrations. For the application
of exciting an atom with a single photon pulse we demonstrate the creation of a
suitable temporal pulse envelope. We infer coupling strengths of 89% and
success probabilities of up to 87% for the application of exciting a single
atom for the current experimental parameters.Comment: to be published in Europ. Phys. J.
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