7,438 research outputs found
Coherent-state phase concentration by quantum probabilistic amplification
We propose novel coherent-state phase concentration by probabilistic
measurement-induced ampli- fication. The amplification scheme uses novel
architecture, thermal noise addition (instead of single photon addition)
followed by feasible multiple photon subtraction using realistic photon-number
resolving detector. It allows to substantially amplify weak coherent states and
simultaneously reduce their phase uncertainty, contrary to the deterministic
amplifier
Development of a container for handling, testing, and storing discrete microelectronic components
A container has been developed for handling, testing, burning-in, and storing discrete microelectronic components without removal from the protective package. The package was designed to accommodate the leadless inverted device and other carrier-mounted active devices and chip-type discrete resistors and capacitors. Before the indicated development, components were handled and tested in various ways, some of which resulted in damage or contamination. The basic design of the container utilizes precision machined printed circuit boards and chemically milled (photoetched) contact springs. Included in this design for protection is an O-ring-sealed cover. Methods of fabrication and limitations of the current hardware are presented. Current applications of and possible extensions to the technology are discussed
Nonlinear static and dynamic analysis of mixed cable elements
This paper presents a family of finite elements for the nonlinear static and dynamic analysis of cables based on a mixed variational formulation in curvilinear coordinates and finite deformations. This formulation identifies stress measures, in the form of axial forces, and conjugate deformation measures for the nonlinear catenary problem. The continuity requirements lead to two distinct implementations: one with a continuous axial force distribution and one with a discontinuous. Two examples from the literature on nonlinear cable analysis are used to validate the proposed formulation for St VenantKirchhoff elastic materials. These studies show that displacements and axial forces are captured with high accuracy for both the static and the dynamic case
Experimental purification of coherent states
We propose a scheme for optimal Gaussian purification of coherent states from
several imperfect copies. The proposal is experimentally demonstrated for the
case of two copies of a coherent state sent through independent noisy channels.
Our purification protocol relies on only linear optics and an ancilla vacuum
state, rendering this approach an interesting alternative to the more complex
protocols of entanglement distillation and quantum error correction
Experimental demonstration of coherent state estimation with minimal disturbance
We investigate the optimal tradeoff between information gained about an
unknown coherent state and the state disturbance caused by the measurement
process. We propose several optical schemes that can enable this task, and we
implement one of them, a scheme which relies on only linear optics and homodyne
detection. Experimentally we reach near optimal performance, limited only by
detection inefficiencies. In addition we show that such a scheme can be used to
enhance the transmission fidelity of a class of noisy channels
Squeezed state purification with linear optics and feed forward
A scheme for optimal and deterministic linear optical purification of mixed
squeezed Gaussian states is proposed and experimentally demonstrated. The
scheme requires only linear optical elements and homodyne detectors, and allows
the balance between purification efficacy and squeezing degradation to be
controlled. One particular choice of parameters gave a ten-fold reduction of
the thermal noise with a corresponding squeezing degradation of only 11%. We
prove optimality of the protocol, and show that it can be used to enhance the
performance of quantum informational protocols such as dense coding and
entanglement generation.Comment: 4 pages, 3 figure
Experimental test of strongly non-classical character of a noisy squeezed single-photon state
We experimentally verify the quantum non-Gaussian character of a
conditionally generated noisy squeezed single-photon state with positive Wigner
function. Employing an optimized witness based on probabilities of squeezed
vacuum and squeezed single-photon states we prove that the state cannot be
expressed as a mixture of Gaussian states. In our experiment, the non-Gaussian
state is generated by conditional subtraction of a single photon from squeezed
vacuum state. The state is probed with a homodyne detector and the witness is
determined by averaging a suitable pattern function over the measured homodyne
data. Our experimental results are in good agreement with a theoretical fit
obtained from a simple yet realistic model of the experimental setup.Comment: 10 pages, 8 figures, REVTeX
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