1,986 research outputs found
Benchmarking of Gaussian boson sampling using two-point correlators
Gaussian boson sampling is a promising scheme for demonstrating a quantum
computational advantage using photonic states that are accessible in a
laboratory and, thus, offer scalable sources of quantum light. In this
contribution, we study two-point photon-number correlation functions to gain
insight into the interference of Gaussian states in optical networks. We
investigate the characteristic features of statistical signatures which enable
us to distinguish classical from quantum interference. In contrast to the
typical implementation of boson sampling, we find additional contributions to
the correlators under study which stem from the phase dependence of Gaussian
states and which are not observable when Fock states interfere. Using the first
three moments, we formulate the tools required to experimentally observe
signatures of quantum interference of Gaussian states using two outputs only.
By considering the current architectural limitations in realistic experiments,
we further show that a statistically significant discrimination between quantum
and classical interference is possible even in the presence of loss, noise, and
a finite photon-number resolution. Therefore, we formulate and apply a
theoretical framework to benchmark the quantum features of Gaussian boson
sampling under realistic conditions
Quantum Correlations from the Conditional Statistics of Incomplete Data
We study, in theory and experiment, the quantum properties of correlated
light fields measured with click-counting detectors providing incomplete
information on the photon statistics. We establish a correlation parameter for
the conditional statistics, and we derive the corresponding nonclassicality
criteria for detecting conditional quantum correlations. Classical bounds for
Pearson's correlation parameter are formulated that allow us, once they are
violated, to determine nonclassical correlations via the joint statistics. On
the one hand, we demonstrate nonclassical correlations in terms of the joint
click statistics of light produced by a parametric down conversion source. On
the other hand, we verify quantum correlations of a heralded, split
single-photon state via the conditional click statistics together with a
generalization to higher-order moments. We discuss the performance of the
presented nonclassicality criteria to successfully discern joint and
conditional quantum correlations. Remarkably, our results are obtained without
making any assumptions on the response function, quantum efficiency, and
dark-count rate of the photodetectors
On the Existence of Periodic Solutions of a Gyrostat Similar to Lagrange’s Gyroscope
In this paper, the problem of the existence ofperiodic solutions of motion ofa gyrostatfixed at one point underthe action ofa central Newtonian force field, and a gyrostatic momentum li (i : 1,2,3; l1 = l2 = 0, l3 not equal 0)similar to a Lagrange gyroscope is investigated. We assume that the center of mass G of this gyrostat isdisplaced by a small quantity relative to the axis of symmetry, and that quantity is used to obtain the smallparameter 8 (Elfimov, 1978). The equations of motion will be studied under certain initial conditions ofmotion.The Poincaré small parameter method (Malkin, 1959; Nayfeh, 1973) is applied to obtain the periodic solutionsof motion. The periodic solutions for the case of irrational frequencies ratio are given. The periodic solutionsare geometrically interpreted to give the forms of Euler angles
A Novel Implantable Glaucoma Valve Using Ferrofluid
Purpose To present a novel design of an implantable glaucoma valve based on ferrofluidic nanoparticles and to compare it with a well-established FDA approved valve. Setting: Massachusetts Eye & Ear Infirmary, Boston, USA. Methods: A glaucoma valve was designed using soft lithography techniques utilizing a water-immiscible magnetic fluid (ferrofluid) as a pressure-sensitive barrier to aqueous flow. Two rare earth micro magnets were used to calibrate the opening and closing pressure. In-vitro flow measurements were performed to characterize the valve and to compare it to Ahmed™ glaucoma valve. The reliability and predictability of the new valve was verified by pressure/flow measurements over a period of three months and X-ray diffraction (XRD) analysis over a period of eight weeks. In vivo assessment was performed in three rabbits. Results: In the in vitro experiments, the opening and closing pressures of the valve were 10 and 7 mmHg, respectively. The measured flow/pressure response was linearly proportional and reproducible over a period of three months (1.8 µl/min at 12 mmHg; 4.3 µl/min at 16 mmHg; 7.6 µl/min at 21 mmHg). X-ray diffraction analysis did not show oxidization of the ferrofluid when exposed to water or air. Preliminary in vivo results suggest that the valve is biocompatible and can control the intraocular pressure in rabbits. Conclusions: The proposed valve utilizes ferrofluid as passive, tunable constriction element to provide highly predictable opening and closing pressures while maintaining ocular tone. The ferrofluid maintained its magnetic properties in the aqueous environment and provided linear flow to pressure response. Our in-vitro tests showed reliable and reproducible results over a study period of three months. Preliminary in-vivo results were very promising and currently more thorough investigation of this device is underway
Detector-Agnostic Phase-Space Distributions
The representation of quantum states via phase-space functions constitutes an
intuitive technique to characterize light. However, the reconstruction of such
distributions is challenging as it demands specific types of detectors and
detailed models thereof to account for their particular properties and
imperfections. To overcome these obstacles, we derive and implement a
measurement scheme that enables a reconstruction of phase-space distributions
for arbitrary states whose functionality does not depend on the knowledge of
the detectors, thus defining the notion of detector-agnostic phase-space
distributions. Our theory presents a generalization of well-known phase-space
quasiprobability distributions, such as the Wigner function. We implement our
measurement protocol, using state-of-the-art transition-edge sensors without
performing a detector characterization. Based on our approach, we reveal the
characteristic features of heralded single- and two-photon states in phase
space and certify their nonclassicality with high statistical significance
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