11,418 research outputs found
Thirty-fold: Extreme gravitational lensing of a quiescent galaxy at
We report the discovery of eMACSJ1341-QG-1, a quiescent galaxy at
located behind the massive galaxy cluster eMACSJ1341.92442 (). The
system was identified as a gravitationally lensed triple image in Hubble Space
Telescope images obtained as part of a snapshot survey of the most X-ray
luminous galaxy clusters at and spectroscopically confirmed in
ground-based follow-up observations with the ESO/X-Shooter spectrograph. From
the constraints provided by the triple image, we derive a first, crude model of
the mass distribution of the cluster lens, which predicts a gravitational
amplification of a factor of 30 for the primary image and a factor of
6 for the remaining two images of the source, making eMACSJ1341-QG-1 by
far the most strongly amplified quiescent galaxy discovered to date. Our
discovery underlines the power of SNAPshot observations of massive, X-ray
selected galaxy clusters for lensing-assisted studies of faint background
populations
Damage Evolution During Fatigue in Structural Materials
AbstractEarly stages of damage evolution in cyclic loading are described and discussed. The importance of the role of cyclic plastic strain in damage evolution is emphasized and the relation between stress and strain in cyclic straining is clarified. The principal stages of damage evolution in fatigued crystalline structural material are identified. The basic characteristic and theories of fatigue crack initiation are sketched and confronted with experimental observations. Early fatigue crack growth is characterized and quantitatively described. The relation between the growth of short cracks and fatigue life in the form of Manson-Coffin law is established
Absorbing-state phase transitions on percolating lattices
We study nonequilibrium phase transitions of reaction-diffusion systems
defined on randomly diluted lattices, focusing on the transition across the
lattice percolation threshold. To develop a theory for this transition, we
combine classical percolation theory with the properties of the supercritical
nonequilibrium system on a finite-size cluster. In the case of the contact
process, the interplay between geometric criticality due to percolation and
dynamical fluctuations of the nonequilibrium system leads to a new universality
class. The critical point is characterized by ultraslow activated dynamical
scaling and accompanied by strong Griffiths singularities. To confirm the
universality of this exotic scaling scenario we also study the generalized
contact process with several (symmetric) absorbing states, and we support our
theory by extensive Monte-Carlo simulations.Comment: 11 pages, 10 eps figures included, final version as publishe
High-Q nested resonator in an actively stabilized optomechanical cavity
Experiments involving micro- and nanomechanical resonators need to be
carefully designed to reduce mechanical environmental noise. A small scale
on-chip approach is to add an additional resonator to the system as a
mechanical low-pass filter. Unfortunately, the inherent low frequency of the
low-pass filter causes the system to be easily excited mechanically. Fixating
the additional resonator ensures that the resonator itself can not be excited
by the environment. This, however, negates the purpose of the low-pass filter.
We solve this apparent paradox by applying active feedback to the resonator,
thereby minimizing the motion with respect the front mirror of an
optomechanical cavity. Not only does this method actively stabilize the cavity
length, but it also retains the on-chip vibration isolation.Comment: Minor adjustments mad
Fiber-top atomic force microscope
We present the implementation of an atomic force microscope (AFM) based on fiber-top design. Our results demonstrate that the performances of fiber-top AFMs in contact mode are comparable to those of similar commercially available instruments. Our device thus represents an interesting\ud
alternative to existing AFMs, particularly for applications outside specialized research laboratories, where a compact, user-friendly, and versatile tool might often be preferred
Coherent Optomechanical State Transfer between Disparate Mechanical Resonators
Hybrid quantum systems have been developed with various mechanical, optical
and microwave harmonic oscillators. The coupling produces a rich library of
interactions including two mode squeezing, swapping interactions, back-action
evasion and thermal control. In a multimode mechanical system, coupling
resonators of different scales (both in frequency and mass) leverages the
advantages of each resonance. For example: a high frequency, easily manipulated
resonator could be entangled with a low frequency massive object for tests of
gravitational decoherence. Here we demonstrate coherent optomechanical state
swapping between two spatially and frequency separated resonators with a mass
ratio of 4. We find that, by using two laser beams far detuned from an optical
cavity resonance, efficient state transfer is possible through a process very
similar to STIRAP (Stimulated Raman Adiabatic Passage) in atomic physics.
Although the demonstration is classical, the same technique can be used to
generate entanglement between oscillators in the quantum regime
Experimental exploration of the optomechanical attractor diagram and its dynamics
We demonstrate experimental exploration of the attractor diagram of an
optomechanical system where the optical forces compensate for the mechanical
losses. In this case stable self-induced oscillations occur but only for
specific mirror amplitudes and laser detunings. We demonstrate that we can
amplify the mechanical mode to an amplitude 500 times larger than the thermal
amplitude at 300K. The lack of unstable or chaotic motion allows us to
manipulate our system into a non-trivial steady state and explore the dynamics
of self-induced oscillations in great detail.Comment: 6 pages, 4 figure
Entanglement dynamics of two-qubit system in different types of noisy channels
In this paper, we study entanglement dynamics of a two-qubit extended
Werner-like state locally interacting with independent noisy channels, i.e.,
amplitude damping, phase damping and depolarizing channels. We show that the
purity of initial entangled state has direct impacts on the entanglement
robustness in each noisy channel. That is, if the initial entangled state is
prepared in mixed instead of pure form, the state may exhibit entanglement
sudden death (ESD) and/or be decreased for the critical probability at which
the entanglement disappear.Comment: 11 pages, 6 figure
Development of a high-sensitivity torsion balance to investigate the thermal Casimir force
We report development of a high-sensitivity torsion balance to measure the
thermal Casimir force. Special emphasis is placed on experimental
investigations of a possible surface electric force originating from surface
patch potentials that have been recently noticed by several experimental
groups. By gaining a proper understanding of the actual contribution of the
surface electric force in real materials, we aim to undertake precision force
measurements to resolve the Casimir force at finite temperature in real metals,
as well as in other semiconducting materials, such as graphene.Comment: Proceedings of the 10th International Conference "Quantum Field
Theory Under the Influence of External Conditions"; 11 pages and 4 figure
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