A delayed choice quantum eraser explained by the transactional interpretation of quantum mechanics

This paper explains the delayed choice quantum eraser of Kim et al. in terms of the transactional interpretation of quantum mechanics by John Cramer. It is kept deliberately mathematically simple to help explain the transactional technique. The emphasis is on a clear understanding of how the instantaneous "collapse" of the wave function due to a measurement at a specific time and place may be reinterpreted as a gradual collapse over the entire path of the photon and over the entire transit time from slit to detector. This is made possible by the use of a retarded offer wave, which is thought to travel from the slits (or rather the small region within the parametric crystal where down-conversion takes place) to the detector and an advanced counter wave traveling backward in time from the detector to the slits. The point here is to make clear how simple the Cramer transactional picture is and how much more intuitive the collapse of the wave function becomes if viewed in this way. Also any confusion about possible retro-causal signaling is put to rest. A delayed choice quantum eraser does not require any sort of backward in time communication. This paper makes the point that it is preferable to use the Transactional Interpretation (TI) over the usual Copenhagen Interpretation (CI) for a more intuitive understanding of the quantum eraser delayed choice experiment. Both methods give exactly the same end results and can be used interchangeably.Comment: 24 pages 4 figures, fifth draf

Mach's principle, Action at a Distance and Cosmology

Hoyle and Narlikar (HN) in the 1960's developed a theory of gravitation which was completely Machian and used both retarded and advanced waves to communicate gravitational influence between particles. The advanced waves, which travel backward in time, are difficult to visualize and although they are mathematically allowed by relativistic wave equations, they never really caught on. The HN theory reduced to Einstein's theory of gravity in the smooth fluid approximation and a transformation into the rest frame of the fluid. Unfortunately the theory has been ignored by much of the General Relativity community since it was developed with the static universe in mind. However, it is easy to drop the static universe condition (by dropping the "C"-field matter creation terms) and then you have a perfectly good theory of gravitation. Hawking in 1965 pointed out a possible flaw in the theory. This involved integrating out into the distant future to account for all the advanced waves which might influence the mass of a particle here and now. Hawking used infinity as his upper time limit and showed the integral was divergent. We would like to point out that since the universe is known to be expanding, and accelerating, the upper limit in the advanced wave time integral should not be infinite but is bounded by the Cosmic Event Horizon. This event horizon $H_e$ represents a barrier between future events that can be observed and those which cannot. We maintain that the advanced integral is in fact finite when the cosmic event horizon is taken into account, since the upper limit of the advanced wave integral becomes $H_e/c$. Hawking's objection is no longer valid and the HN theory becomes a working theory once again.Comment: The work is related to advanced waves and Cramer's transactional interpretation of quantum mechanics. The paper has been submitted to the Journal of Modern Physics (jmp) a special issue on "Gravitation, Astrophysics and Cosmology

Analytical robustness of quantitative NIR chemical imaging for Islamic paper characterization

Recently, spectral imaging techniques such as Multispectral (MSI) and Hyperspectral Imaging (HSI) have gained importance in the field of heritage conservation. This paper explores the analytical robustness of quantitative chemical imaging for Islamic paper characterization by focusing on the effect of different measurement and processing parameters, i.e. acquisition conditions and calibration on the accuracy of the collected spectral data. This will provide a better understanding of the technique that can provide a measure of change in collections through imaging. For the quantitative model, special calibration target was devised using 105 samples from a well-characterized reference Islamic paper collection. Two material properties were of interest: starch sizing and cellulose degree of polymerization (DP). Multivariate data analysis methods were used to develop discrimination and regression models which were used as an evaluation methodology for the metrology of quantitative NIR chemical imaging. Spectral data were collected using a pushbroom HSI scanner (Gilden Photonics Ltd) in the 1000-2500 nm range with a spectral resolution of 6.3 nm using a mirror scanning setup and halogen illumination. Data were acquired at different measurement conditions and acquisition parameters. Preliminary results showed the potential of the evaluation methodology to show that measurement parameters such as the use of different lenses and different scanning backgrounds may not have a great influence on the quantitative results. Moreover, the evaluation methodology allowed for the selection of the best pre-treatment method to be applied to the data. © (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only

Confidence intervals for robust estimates of measurement uncertainty

Uncertainties arising at different stages of a measurement process can be estimated using Analysis of Variance (ANOVA) on duplicated measurements. In some cases it is also desirable to calculate confidence intervals for these uncertainties. This can be achieved using probability models that assume the measurement data are normally distributed. However, it is often the case in practice that a set of otherwise normally distributed measurement values is contaminated by a small number of outlying values, which may have a disproportionate effect on the variances calculated using the ‘classical’ form of ANOVA. In this case, robust ANOVA methods are able to provide variance estimates that are much closer to the parameters of the underlying normal distributions. A method using bootstrapping to calculate confidence intervals from robust estimates of variances is proposed and evaluated, and is shown to work well when the number of outlying values is small. The method has been implemented in a Visual Basic program

Quantitative chemical near-infrared hyperspectral imaging of Islamic paper

Heritage objects are well known for their compositional inhomogeneity due to materials and processes used in their production. Hyperspectral imaging is gaining importance in the field of heritage conservation by expanding spectroscopy to the examination of an entire surface of an object. This paper focuses on the application of near-infrared hyperspectral imaging to the characterisation of Islamic paper using a pushbroom HSI scanner in the 1000–2500 nm range to collect hyperspectral datacubes. A calibration target was devised using 105 samples from the well-characterised reference Islamic paper collection of the UCL Institute for Sustainable Heritage. Two material properties of Islamic paper were of interest: starch sizing and degree of polymerisation (DP). In addition to the developed discrimination and regression models using multivariate data analysis methods, a quantitative chemical map of the DP of an Islamic paper was generated as a case study for improved visualisation of the inhomogeneity of material properties, of value to researchers and conservators. As a case study, this research shows the wealth of valuable chemical information that near-infrared hyperspectral imaging could provide for diverse heritage applications in the future

Two-photon coincident-frequency-entanglement via extended phase matching

We demonstrate a new class of frequency-entangled states generated via spontaneous parametric down-conversion under extended phase matching conditions. Biphoton entanglement with coincident signal and idler frequencies is observed over a broad bandwidth in periodically poled KTiOPO$_4$. We demonstrate high visibility in Hong-Ou-Mandel interferometric measurements under pulsed pumping without spectral filtering, which indicates excellent frequency indistinguishability between the down-converted photons. The coincident-frequency entanglement source is useful for quantum information processing and quantum measurement applications.Comment: 4 pages, 3 figures, submitted to PR

The UK Research Assessment Exercise (RAE 2008) and retail research output

The 2008 Research Assessment Exercise (RAE) in the United Kingdom provides a further opportunity to consider changing trends and patters in retail research, following on a previous commentary (Dawson et al. 2004). This comparison with shows that pressures continue to mount and are impacting retail knowledge creation and dissemination practices, not least in terms of those engaged in retail research, the topics and approaches utilised, the publication tactics and strategies and thus the standing of retail research in the UK and its reputation internationall