5,011 research outputs found
Comment on "Evidence for Quantized Displacement in Macroscopic Nanomechanical Oscillators"
In a recent Letter, Gaidarzhy et al. [1] claim to have observed evidence for "quantized displacements" of a high-order mode of a nanomechanical oscillator. We contend that the methods employed by the authors are unsuitable in principle to observe such states for any harmonic mode
Quantum gears: a simple mechanical system in the quantum regime
Abstract. The quantum mechanics of a simple mechanical system is considered. A group of gears can serve as a model for several different systems such as an artifically constructed nanomechanical device or a group of ring molecules. It is shown that the classical motion of the gears in which the angular velocities are locked together does not correspond to
High-Frequency Nanofluidics: An Experimental Study using Nanomechanical Resonators
Here we apply nanomechanical resonators to the study of oscillatory fluid
dynamics. A high-resonance-frequency nanomechanical resonator generates a
rapidly oscillating flow in a surrounding gaseous environment; the nature of
the flow is studied through the flow-resonator interaction. Over the broad
frequency and pressure range explored, we observe signs of a transition from
Newtonian to non-Newtonian flow at , where is a
properly defined fluid relaxation time. The obtained experimental data appears
to be in close quantitative agreement with a theory that predicts purely
elastic fluid response as
Nonlinear response of a driven vibrating nanobeam in the quantum regime
We analytically investigate the nonlinear response of a damped doubly clamped
nanomechanical beam under static longitudinal compression which is excited to
transverse vibrations. Starting from a continuous elasticity model for the
beam, we consider the dynamics of the beam close to the Euler buckling
instability. There, the fundamental transverse mode dominates and a quantum
mechanical time-dependent effective single particle Hamiltonian for its
amplitude can be derived. In addition, we include the influence of a
dissipative Ohmic or super-Ohmic environment. In the rotating frame, a
Markovian master equation is derived which includes also the effect of the
time-dependent driving in a non-trivial way. The quasienergies of the pure
system show multiple avoided level crossings corresponding to multiphonon
transitions in the resonator. Around the resonances, the master equation is
solved analytically using Van Vleck perturbation theory. Their lineshapes are
calculated resulting in simple expressions. We find the general solution for
the multiple multiphonon resonances and, most interestingly, a bath-induced
transition from a resonant to an antiresonant behavior of the nonlinear
response.Comment: 25 pages, 5 figures, submitted to NJ
Entanglement and decoherence of a micromechanical resonator via coupling to a Cooper box
We analyse the quantum dynamics of a micromechanical resonator capacitively
coupled to a Cooper box. With appropriate quantum state control of the Cooper
box, the resonator can be driven into a superposition of spatially separated
states. The Cooper box can also be used to probe the environmentally-induced
decoherence of the resonator superposition state.Comment: 4 pages, 3 figure
Dynamics of a suspended nanowire driven by an ac Josephson current in an inhomogeneous magnetic field
We consider a voltage-biased nanoelectromechanical Josephson junction, where
a suspended nanowire forms a superconducting weak-link, in an inhomogeneous
magnetic field. We show that a nonlinear coupling between the Josephson current
and the magnetic field generates a Laplace force that induces a whirling motion
of the nanowire. By performing an analytical and a numerical analysis, we
demonstrate that at resonance, the amplitude-phase dynamics of the whirling
movement present different regimes depending on the degree of inhomogeneity of
the magnetic field: time independent, periodic and chaotic. Transitions between
these regimes are also discussed.Comment: 7 pages, 5 figure
Cooling Torsional Nanomechanical Vibration by Spin-Orbit Interactions
We propose and study a spin-orbit interaction based mechanism to actively
cool down the torsional vibration of a nanomechanical resonator made by
semiconductor materials. We show that the spin-orbit interactions of electrons
can induce a coherent coupling between the electron spins and the torsional
modes of nanomechanical vibration. This coherent coupling leads to an active
cooling for the torsional modes via the dynamical thermalization of the
resonator and the spin ensemble.Comment: 4 pages, 3 figure
Generation of Squeezed States of Nanomechanical Resonators by Reservoir Engineering
An experimental demonstration of a non-classical state of a nanomechanical
resonator is still an outstanding task. In this paper we show how the resonator
can be cooled and driven into a squeezed state by a bichromatic microwave
coupling to a charge qubit. The stationary oscillator state exhibits a reduced
noise in one of the quadrature components by a factor of 0.5 - 0.2. These
values are obtained for a 100 MHz resonator with a Q-value of 10 to 10
and for support temperatures of T 25 mK. We show that the coupling to
the charge qubit can also be used to detect the squeezed state via measurements
of the excited state population. Furthermore, by extending this measurement
procedure a complete quantum state tomography of the resonator state can be
performed. This provides a universal tool to detect a large variety of
different states and to prove the quantum nature of a nanomechanical
oscillator.Comment: 13 pages,9 figure
Giant slip lengths of a simple fluid at vibrating solid interfaces
It has been shown recently [PRL 102, 254503 (2009)] that in the plane-plane
configuration a mechanical resonator vibrating close to a rigid wall in a
simple fluid can be overdamped to a frozen regime. Here, by solving
analytically the Navier Stokes equations with partial slip boundary conditions
at the solid fluid interface, we develop a theoretical approach justifying and
extending these earlier findings. We show in particular that in the perfect
slip regime the above mentioned results are, in the plane-plane configuration,
very general and robust with respect to lever geometry considerations. We
compare the results with those obtained previously for the sphere moving
perpendicularly and close to a plane in a simple fluid and discuss in more
details the differences concerning the dependence of the friction forces with
the gap distance separating the moving object (i.e., plane or sphere) from the
fixed plane. Finally, we show that the submicron fluidic effect reported in the
reference above, and discussed further in the present work, can have dramatic
implications in the design of nano-electromechanical systems (NEMS).Comment: submitted to PRE (see also PRL 102, 254503 (2009)
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