946 research outputs found
Verzeichnis der bei der Abteilung Fischereibiologie der Biologischen Anstalt Helgoland eingelieferten markierten Fische 1. Januar bis 31. Dezember 1958
Bericht über die 30. Reise des FFS "Anton Dohrn" in die südliche und mittlere Nordsee vom 24.6. - 5.7.1958
Microwave cavity-enhanced transduction for plug and play nanomechanics at room temperature
Nanomechanical resonators with increasingly high quality factors are enabled
following recent insights into energy storage and loss mechanisms in
nanoelectromechanical systems (NEMS). Consequently, efficient, non-dissipative
transduction schemes are required to avoid the dominating influence of coupling
losses. We present an integrated NEMS transducer based on a microwave cavity
dielectrically coupled to an array of doubly-clamped pre-stressed silicon
nitride beam resonators. This cavity-enhanced detection scheme allows resolving
the resonators' Brownian motion at room temperature while preserving their high
mechanical quality factor of 290,000 at 6.6 MHz. Furthermore, our approach
constitutes an "opto"mechanical system in which backaction effects of the
microwave field are employed to alter the effective damping of the resonators.
In particular, cavity-pumped self-oscillation yields a linewidth of only 5 Hz.
Thereby, an adjustement-free, all-integrated and self-driven
nanoelectromechanical resonator array interfaced by just two microwave
connectors is realised, potentially useful for applications in sensing and
signal processing
A double-dot quantum ratchet driven by an independently biased quantum point contact
We study a double quantum dot (DQD) coupled to a strongly biased quantum
point contact (QPC), each embedded in independent electric circuits. For weak
interdot tunnelling we observe a finite current flowing through the unbiased
Coulomb blockaded DQD in response to a strong bias on the QPC. The direction of
the current through the DQD is determined by the relative detuning of the
energy levels of the two quantum dots. The results are interpreted in terms of
a quantum ratchet phenomenon in a DQD energized by a nearby QPC.Comment: revised versio
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