Squeezed states of the electromagnetic field have been generated by nondegenerate four-wave mixing due to Na atoms in an optical cavity. The optical noise in the cavity, comprised of primarily vacuum fluctuations and a small component of spontaneous emission from the pumped Na atoms, is amplified in one quadrature of the optical field and deamplified in the other quadrature. These quadrature components are measured with a balanced homodyne detector. The total noise level in the deamplified quadrature drops below the vacuum noise level.

Observation of squeezed states generated by four-wave mixing in an optical cavity

Journal of Physics Condensed Matter: Preface

Package-X: A Mathematica package for the analytic calculation of one-loop integrals

FeynCalc 9.3: New features and improvements

Developing a comprehensive method to compute bond orders is a problem that has eluded chemists since Lewis's pioneering work on chemical bonding a century ago. Here, a computationally efficient method solving this problem is introduced and demonstrated for diverse materials including elements from each chemical group and period. The method is applied to non-magnetic, collinear magnetic, and non-collinear magnetic materials with localized or delocalized bonding electrons. Examples studied include the stretched O2 molecule, 26 diatomic molecules, 3d and 5d transition metal solids, periodic materials with 1 to 8748 atoms per unit cell, a biomolecule, a hypercoordinate molecule, an electron deficient molecule, hydrogen bound systems, transition states, Lewis acid–base complexes, aromatic compounds, magnetic systems, ionic materials, dispersion bound systems, nanostructures, and other materials. From near-zero to high-order bonds were studied. Both the bond orders and the sum of bond orders for each atom are accurate across various bonding types: metallic, covalent, polar-covalent, ionic, aromatic, dative, hypercoordinate, electron deficient multi-centered, agostic, and hydrogen bonding. The method yields similar results for correlated wavefunction and density functional theory inputs and for different SZ values of a spin multiplet. The method requires only the electron and spin magnetization density distributions as input and has a computational cost scaling linearly with increasing number of atoms in the unit cell. No prior approach is as general. The method does not apply to electrides, highly time-dependent states, some extremely high-energy excited states, and nuclear reactions.

/pdf/introducing-ddec6-atomic-population-analysis-part-3-2apvo8oc0k.pdf

Introducing DDEC6 atomic population analysis: part 3. Comprehensive method to compute bond orders

According to Heisenberg, the more precisely, say, the position of a particle is measured, the less precisely we can determine its momentum. The uncertainty principle in its original form ignores, however, the unavoidable effect of recoil in the measuring device. An experimental test now validates an alternative relation, and the uncertainty principle in its original formulation is broken.

/pdf/experimental-demonstration-of-a-universally-valid-error-3z3p0mmnhj.pdf

Experimental demonstration of a universally valid error-disturbance uncertainty relation in spin measurements

In its original formulation, Heisenberg's uncertainty principle dealt with the relationship between the error of a quantum measurement and the thereby induced disturbance on the measured object. Meanwhile, Heisenberg's heuristic arguments have turned out to be correct only for special cases. An alternative universally valid relation was derived by Ozawa in 2003. Here, we demonstrate that Ozawa's predictions hold for projective neutron-spin measurements. The experimental inaccessibility of error and disturbance claimed elsewhere has been overcome using a tomographic method. By a systematic variation of experimental parameters in the entire configuration space, the physical behavior of error and disturbance for projective spin-$\frac{1}{2}$ measurements is illustrated comprehensively. The violation of Heisenberg's original relation, as well as the validity of Ozawa's relation become manifest. In addition, our results conclude that the widespread assumption of a reciprocal relation between error and disturbance is not valid in general.

Violation of Heisenberg's error-disturbance uncertainty relation in neutron-spin measurements

Experiments on neutrons confirm an information-theoretic formulation of Heisenberg's noise-disturbance uncertainty principle: There is a reciprocal trade-off in knowledge of two incompatible spin observables.

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Experimental Test of Entropic Noise-Disturbance Uncertainty Relations for Spin-1/2 Measurements.

The indeterminacy inherent in quantum measurements is an outstanding character of quantum theory, which manifests itself typically in the uncertainty principle. In the last decade, several universally valid forms of error-disturbance uncertainty relations were derived for completely general quantum measurements for arbitrary states. Subsequently, Branciard established a form that is optimal for spin measurements for some pure states. However, the bound in his inequality is not stringent for mixed states. One of the present authors recently derived a new bound tight in the corresponding mixed state case. Here, a neutron-optical experiment is carried out to investigate this new relation: it is tested whether error and disturbance of quantum measurements disappear or persist in mixing up the measured ensemble. The attainability of the new bound is experimentally observed, falsifying the tightness of Branciard's bound for mixed spin states.

Experimental Test of Residual Error-Disturbance Uncertainty Relations for Mixed Spin- ½ States

Energy consumption is continuously increasing worldwide and thus, in the sense of sustainability and environmentalism, focus on renewable energy sources has been strongly enhanced. As far as the exploitation of solar energy is concerned, the electricitygenerating capacity of photovoltaics (PV) has experienced a considerable growth over the last decades1 and the European Union established the objective of a 12% share of its total electricity demand until 2020.1 The fundamental building block of any PVsystem is the solar cell. Being basically a diode whose pn junction is exposed to light its functioning is explained in detail by semiconductor theory.2,3 For practical purposes however, the microscopic processes are modeled by equivalent circuit diagrams allowing to obtain the cell’s currentvoltage characteristics (IVcurve) with sufficient accuracy and within reasonable calculational effort. Determining the parameters of the single cell’s circuit model is essential for evaluation, dimensioning, and manufacturing of PVmodules and entire PVsystems. Moreover, the exact knowledge of the model parameters allows to draw conclusions about inner cell processes and can serve as starting point for further research and cell optimization. In the literature, two lumped circuit models are prevalent, the singlediode model4-7 and the twodiode model.8-13 Obtaining the respective model parameters by fitting measured data points to the theoretical IVcurve is aggravated by Received: 28 February 2018 | Revised: 24 May 2018 | Accepted: 2 July 2018 DOI: 10.1002/ese3.216

https://onlinelibrary.wiley.com/doi/pdf/10.1002/ese3.216

Georg Sulyok

Papers

Experimental demonstration of a universally valid error-disturbance uncertainty relation in spin measurements

Violation of Heisenberg's error-disturbance uncertainty relation in neutron-spin measurements

Experimental Test of Entropic Noise-Disturbance Uncertainty Relations for Spin-1/2 Measurements.

Experimental Test of Residual Error-Disturbance Uncertainty Relations for Mixed Spin- ½ States

Extraction of a photovoltaic cell's double-diode model parameters from data sheet values