相关论文: Investigation of mechanical losses of thin silicon…
Our study shows that deposited Ge and Si dielectric thin-films can exhibit low microwave losses at near single-photon powers and sub-Kelvin temperatures ($\approx$40 mK). This low loss enables their use in a wide range of devices, including…
Laser excitation in silicon from femto- to pico-second time scales is studied. We assume the Three-Temperature Model (3TM) which describes the dynamics of the distinct quasi-temperatures for electrons, holes, and lattice. Numerical results…
We report low-temperature measurements of dissipation in megahertz-range, suspended, single-crystal nanomechanical oscillators. At millikelvin temperatures, both dissipation (inverse quality factor) and shift in the resonance frequency…
Internal friction and speed of sound of a-SiO(2) was measured above 6 mK using a torsional oscillator at 90 kHz, controlling for thermal decoupling, non-linear effects, and clamping losses. Strain amplitudes e(A) = 10^{-8} mark the…
Ultralow dissipation plays an important role in sensing applications and exploring macroscopic quantum phenomena using micro-and nano-mechanical systems. We report a diamagnetic-levitated micro-mechanical oscillator operating at a low…
Superconducting resonators used in millimeter-submillimeter astronomy would greatly benefit from deposited dielectrics with a small dielectric loss. We deposited hydrogenated amorphous silicon films using plasma-enhanced chemical vapor…
Investigations into the propagation characteristics, specifically loss and wave velocity, of superconducting coplanar waveguides and microstrip lines were conducted at a 2 mm wavelength. This was achieved through the measurement of on-chip…
We report here on measurements of the reflectivity and loss tangent measured in the W-band (80-125 GHz) and D-band (125-180 GHz) in two samples of float zone silicon with intrinsic stoichiometry - one irradiated by neutrons, which increases…
Measuring very small forces, particularly those of a gravitational nature, has always been of great interest, as fundamental tests of our understanding of the physical laws. Ultra-long period mechanical oscillators, typically used in such…
Processing results of measurements of linear thermal expansion coefficients and linear thermal expansion of two brands of borosilicate glasses --- LK5 and Borofloat 33 --- are presented. The linear thermal expansion of glass samples have…
Materials with thermal-invariant elastic properties of materials are of interest for resonant device frequency and dimensional stability of precision devices. Here, we demonstrate that the temperature coefficient of elasticity (TCE) of…
Dissipation in amorphous solids at low frequencies is commonly attributed to activated transitions of isolated two-level systems (TLS) that come in resonance with elastic or electric fields. Materials with low mechanical or dielectric loss…
We report investigations of conductance fluctuations (noise) in doped silicon at low temperatures (T$<20$K) as it is tuned through the metal-insulator transition (MIT). The scaled magnitude of noise, $\gamma_H$, increases with decrease in T…
Fundamental mechanical loss mechanisms exist even in very pure materials, for instance, due to the interactions of excited acoustic waves with thermal phonons. A reduction of these losses in a certain frequency range is desired in high…
Electron excitations at silicon and 3C-SiC surfaces caused by an intense femtosecond laser pulse can be calculated by solving the time-dependent density functional theory and the Maxwell's equation simultaneously. The energy absorption,…
The cooling of two-dimensional electrons in silicon-metal-oxide semiconductor field effect transistors is studied experimentally. Cooling to the lattice is found to be more effective than expected from the bulk electron-phonon coupling in…
We present millimeter and sub-millimeter room temperature transmission and loss measurements of 3D printed alumina disc and of a disc with one-sided 3D printed sub-wavelength structures anti-reflection coatings (SWS-ARC). For four bands…
This paper demonstrates cooling of the center-of-mass motion of 10 $\mu$m-diameter optically levitated silica spheres to an effective temperature of $50\pm22 \mu$K, achieved by minimizing the technical pointing noise of the trapping laser.…
We analyze the dissipation of the frequency vibrations of nano-mechanical devices. We show that the coupling between flexural modes and two-level systems leads to sub-ohmic dissipation. The inverse quality factor of the low energy…
The internal friction of e-beam amorphous silicon was measured in a magnetic field between 0 and 6 T, from 1.5-20 K, and was found to be independent of the field to better than 8%. It is concluded that the low energy excitations observed in…