Temperature coefficients of crystalline-quartz elastic constants over the cryogenic range [4 K, 15 K]

This paper brings out results of a measurement campaign aiming to determine the temperature coefficients of synthetic quartz elastic constants at liquid helium temperature. The method is based on the relationship between the resonance frequencies of a quartz acoustic cavity and the elastic constants of the material. The temperature coefficients of the elastic constants are extracted from experimental frequency-temperature data collected from a set of resonators of various cut angles, because of the anisotropy of quartz, measured on the very useful cryogenic range [4 K - 15 K]. The knowledge of these temperature coefficients would allow to further design either quartz temperature sensors or conversely frequency-temperature compensated quartz cuts. With extremely low losses, lower than $10^{-9}$ for the best ones, key applications of such devices are ultra-low loss mechanical systems used in many research areas including frequency control and fundamental measurements. The Eulerian formalism is used in this study to identify the temperature coefficients.Comment: 6 pages,4 figure

Dual mode, multiple electrodes Quartz Sensor.

International audienceWe present a method to design the electrodes shape of contoured BAW resonators intended to serve as temperature compensated force sensors. Those are based on simultaneous operation on two families of modes: fast shear B-mode and slow shear C-mode. Use of anharmonic modes instead of main overtone ones provides the possibility of spatial separation of vibrating areas, each mode being driven by separated pairs of electrodes. Electronic circuitry is greatly simplified and force deriving is straightforward

Extremely Low-Loss Acoustic Phonons in a Quartz Bulk Acoustic Wave Resonator at Millikelvin Temperature

Low-loss, high frequency acoustic resonators cooled to millikelvin temperatures are a topic of great interest for application to hybrid quantum systems. When cooled to 20 mK, we show that resonant acoustic phonon modes in a Bulk Acoustic Wave (BAW) quartz resonator demonstrate exceptionally low loss (with $Q$-factors of order billions) at frequencies of 15.6 and 65.4 MHz, with a maximum $f.Q$ product of 7.8$\times10^{16}$ Hz. Given this result, we show that the $Q$-factor in such devices near the quantum ground state can be four orders of magnitude better than previously attained. Such resonators possess the low losses crucial for electromagnetic cooling to the phonon ground state, and the possibility of long coherence and interaction times of a few seconds, allowing multiple quantum gate operations

Volume Dependence in Handel's Model of Quartz Crystal Resonator Noise

International audienceAlthough criticized by many, Handel's quantum model for 1/f noise remains the only model giving a quantitative estimation of the level of intrinsic 1/f noise in quartz crystal resonators that is compatible with the best experimental results. In this paper, we reconsider the volume dependence in this model. We first argue that an acoustic volume, representing the volume in which the vibration energy is trapped, should be used instead of the geometrical volume between the electrodes. Then, we show that because there is an implicit dependence of the quality factor of the resonator with its thickness, the net effect of Handel's formula is not an increase of noise proportionally to the thickness of the resonator, as could be naïvely expected, but a net decrease when thickness increases. Finally, we show that a plot of Q4Sy versus the acoustic volume, instead of the usual Sy plot, could be useful to compare the quality of acoustic resonators having very different resonance frequencies

Comparative material study between PZT ceramic and newer crystalline PMN-PT and PZN-PT mateirals for composite bimorph actuators.

International audienceThe advent of commercially available giant piezoelectric coefficient monocrystalline materials such as PMN-PT (lead magnesium niobate - lead titanate) or PZN-PT (lead zinc niobate - lead titanate) broadens the gate for silicon-integrated applications (PiezoMEMS). Becoming more compatible with microtechnology batch processes, further advances are expected in terms of miniaturization, optimization, functionality or integration with electronics, all while reducing manufacturing costs. Subsequently, operating voltage will be lower and devices response time will improve dramatically. The paper compiles a base knowledge for composite bimorph actuators in line with a bottom-up approach for further more complex piezoelectric device designs such as "microrobots-on-chips". Material properties and constitutive equations of piezoelectric bimorph cantilevers are initially overviewed. Analytical and finite elements modeling (FEM) are afterwards performed on two designs : classical PZT on copper cantilevers and innovative PMN-PT and PZN-PT on silicon. Comparative results clearly report quantitative improvement of PMN-PT on Si design in terms of tip displacement and blocking force

A new method of probing mechanical losses of coatings at cryogenic temperatures

A new method of probing mechanical losses and comparing the corresponding deposition processes of metallic and dielectric coatings in 1-100 MHz frequency range and cryogenic temperatures is presented. The method is based on the use of extremely high-quality quartz acoustic cavities whose internal losses are orders of magnitude lower than any available coatings nowadays. The approach is demonstrated for Chromium, Chromium/Gold and a multilayer tantala/silica coatings. The ${\rm Ta}_2{\rm O}_5/{\rm Si}{\rm O}_2$ coating has been found to exhibit a loss angle lower than $1.6\times10^{-5}$ near 30 {\rm MHz} at 4 {\rm K}. The results are compared to the previous measurements

Widefield two laser interferometry

A novel system has been developed that can capture the wide- field interference pattern generated by interfering two independent and incoherent laser sources. The interferograms are captured using a custom CMOS modulated light camera (MLC) which is capable of demodulating light in the megahertz region. Two stabilised HeNe lasers were constructed in order to keep the optical frequency difference (beat frequency) between the beams within the operational range of the camera. This system is based on previously reported work of an ultrastable heterodyne interferometer [Opt. Express 20, 17722 (2012)]. The system used an electronic feedback system to mix down the heterodyne signal captured at each pixel on the camera to cancel out the effects of time varying piston phase changes observed across the array. In this paper, a similar technique is used to track and negate the effects of beat frequency variations across the two laser pattern. This technique makes it possible to capture the full field interferogram caused by interfering two independent lasers even though the beat frequency is effectively random. As a demonstration of the system’s widefield interferogram capture capability, an image of a phase shifting object is taken using a very simple two laser interferometer

Gyromètre à quartz 2-D micro-usine

Indispensables pour la navigation inertielle, les gyroscopes et les gyromètres font l'objet de nombreuses recherches, particulièrement dans le domaine microtechnique. Le travail de recherche proposé par SFIM industries (puis SAGEM à partir de 1999) consistait à démontrer le principe d'une mesure sur deux axes de la vitesse angulaire, principe dont le brevet est détenu par SFIM. Le principe d'usinabilité du quartz par attaque chimique de dispositifs de ce type ayant été démontré dans un avant-projet, il restait à valider le principe de fonctionnement par la réalisation du capteur et de l'électronique permettant de mesurer la vitesse angulaire...BESANCON-BU Sciences Staps (250562103) / SudocSudocFranceF

Theoretical investigations of temperature-compensated cuts for vibrating beam LGT resonators

International audienceIn this paper, the possibility of temperaturecompensated cuts for different kinds of vibrations in Langatate resonators is investigated. Theoretical investigations of vibrating beam resonators with a rectangular cross-section in extensional, flexural and torsional modes are given