1,346 research outputs found
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
Bounds on higher-order Lorentz-violating photon sector coefficients from an asymmetric optical ring resonator experiment
Optical resonators provide a powerful tool for testing aspects of Lorentz
invariance. Here, we present a reanalysis of an experiment where a path
asymmetry was created in an optical ring resonator by introducing a dielectric
prism in one arm. The frequency difference of the two fundamental
counter-propagating modes was then recorded as the apparatus was
orientation-modulated in the laboratory. By assuming that the minimal
Standard-Model Extension coefficients vanish we are able to place bounds on
higher-order parity-odd Lorentz-violating coefficients of the Standard-Model
Extension. The results presented in this work set the first constraints on two
previously unbounded linear combinations of d=8 parity-odd nonbirefringent
nondispersive coefficients of the photon sector.Comment: 6 pages, 4 figures, 3 tables, accepted for publication in Physics
Letters
High Resolution Flicker-Noise-Free Frequency Measurements of Weak Microwave Signals
Amplification is usually necessary when measuring the frequency instability
of microwave signals. In this work, we develop a flicker noise free frequency
measurement system based on a common or shared amplifier. First, we show that
correlated flicker phase noise can be cancelled in such a system. Then we
compare the new system with the conventional by simultaneously measuring the
beat frequency from two cryogenic sapphire oscillators with parts in 10^15
fractional frequency instability. We determine for low power, below -80 dBm,
the measurements were not limited by correlated noise processes but by thermal
noise of the readout amplifier. In this regime, we show that the new readout
system performs as expected and at the same level as the standard system but
with only half the number of amplifiers. We also show that, using a standard
readout system, the next generation of cryogenic sapphire oscillators could be
flicker phase noise limited when instability reaches parts in 10^16 or betterComment: Accepted for publication in IEEE Transactions on Microwave Theory &
Technique
Improved test of Lorentz Invariance in Electrodynamics using Rotating Cryogenic Sapphire Oscillators
We present new results from our test of Lorentz invariance, which compares
two orthogonal cryogenic sapphire microwave oscillators rotating in the lab. We
have now acquired over 1 year of data, allowing us to avoid the short data set
approximation (less than 1 year) that assumes no cancelation occurs between the
and parameters from the photon
sector of the standard model extension. Thus, we are able to place independent
limits on all eight and parameters.
Our results represents up to a factor of 10 improvement over previous non
rotating measurements (which independently constrained 7 parameters), and is a
slight improvement (except for ) over results from
previous rotating experiments that assumed the short data set approximation.
Also, an analysis in the Robertson-Mansouri-Sexl framework allows us to place a
new limit on the isotropy parameter of
, an improvement of a factor of 2.Comment: Accepted for publication in Phys. Rev.
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
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