88 research outputs found
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 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
Observation of Low Temperature Magneto-Mechanic Effects in Crystalline Resonant Phonon Cavities
We observe magnetic effects in ultra-high quality factor crystalline quartz
Bulk Acoustic Wave resonators at milli-Kelvin temperature. The study reveals
existence of hysteresis loops, jumps and memory effects of acoustical resonance
frequencies. These loops arise as a response to the external magnetic field and
span over few Hertz range for modes with linewidths of about mHz, which
constitute a frequency shift of order 60 linewidths. The effects are broadband
but get stronger towards higher frequencies where both nonlinear effects and
losses are limited by two level systems. This suggests that the observed
effects are due to ferromagnet-like phase of a spin ensemble coupled to
mechanical modes. The observed coupling between mechanical and spin degrees of
freedom in the ultra low loss regime brings new possibilities for the emerging
class of quantum hybrid systems
Advances in Development of Quartz Crystal Oscillators at Liquid Helium Temperatures
This work presents some recent results in the field of liquid helium {bulk
acoustic wave} oscillators. The discussion covers the whole development
procedure starting from component selection and characterization and concluding
with actual phase noise measurements. The associated problems and limitations
are discussed. The unique features of obtained phase noise power spectral
densities are explained with a proposed extension of the Leeson effect.Comment: Cryogenics, 201
Inducing Strong Non-Linearities in a Phonon Trapping Quartz Bulk Acoustic Wave Resonator Coupled to a Superconducting Quantum Interference Device
A quartz Bulk Acoustic Wave resonator is designed to coherently trap phonons
in a way that they are well confined and immune to suspension losses so they
exhibit extremely high acoustic -factors at low temperature, with products of order Hz. In this work we couple such a resonator to a
SQUID amplifier and investigate effects in the strong signal regime. Both
parallel and series connection topologies of the system are investigated. The
study reveals significant non-Duffing response that is associated with the
nonlinear characteristics of Josephson junctions. The nonlinearity provides
quasi-periodic structure of the spectrum in both incident power and frequency.
The result gives an insight into the open loop behaviour of a future Cryogenic
Quartz Oscillator in the strong signal regime
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 -factors of order billions) at frequencies of 15.6 and 65.4 MHz, with
a maximum product of 7.8 Hz. Given this result, we show
that the -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
A very high speed method to simulate quartz crystal oscillator
International audienceIn this paper, we present the SHA method, a Symbolic Harmonic Analysis method to simulate the behaviour of ultrastable quartz crystal oscillators. This nonlinear method is aimed to compute very quickly the steady state as well as amplitude and frequency transients. The ultimate goal is to see instantaneously the influence of a parameter change on the oscillator's features thank to the computation speed. The method proposed here is a mixing of the nonlinear dipolar method previouly developed in our team and the harmonic method. It allows to replace the set of algebro-differential equation of the circuit by a nonlinear system of the Fourier coefficients of the circuit unknowns
Advanced bridge instrument for the measurement of the phase noise and of the short-term frequency stability of ultra-stable quartz resonators
High-stability quartz oscillators are needed in a number of space applications. A short-term stability of parts in 10^{-14} [Allan deviation Ïy(Ï) ] is sometimes required, for integration time Ï of approximately 1-10 s. The Centre National d'Etudes Spatiales (CNES) and the FEMTO-ST Institute (formerly LPMO and LCEP), have been collaborating for many years in this domain, aiming at measuring and at understanding the oscillator noise. The highest stability has been observed on 5 MHz and 10 MHz bulk acoustic-wave resonators. Yet this stability is still not sufficient, or the the manufacturing method is not reproducible. Recently, the analysis of a few premium-stability oscillators has demonstrated that the oscillator frequency instability is due to the fluctuation of the resonator natural frequency, rather than to the noise of the sustaining amplifier via the Leeson effect. It is therefore natural to give attention to the measurement of the resonator fluctuations
Bruit des oscillateurs et des résonateurs à quartz
Un des problÚmes qui se posent au concepteur des oscillateurs à quartz de haute stabilité est le bruit propre des résonateurs. Nous effectuons tout d'abord une brÚve description des principaux mécanismes susceptibles d'affecter la stabilité des oscillateurs et des résonateurs à quartz. Ensuite sont explicitées les grandeurs mises en jeu dans la métrologie des fréquences : la densité spectrale de bruit de phase dans le domaine spectral et la variance d'Allan dans le domaine temporel. Enfin nous présentons l'instrumentation utilisée et développée pour la mesure du bruit des oscillateurs en général et des résonateurs en particulier
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