A first experimental test of de Broglie-Bohm theory against standard quantum mechanics

De Broglie - Bohm (dBB) theory is a deterministic theory, built for reproducing almost all Quantum Mechanics (QM) predictions, where position plays the role of a hidden variable. It was recently shown that different coincidence patterns are predicted by QM and dBB when a double slit experiment is realised under specific conditions and, therefore, an experiment can test the two theories. In this letter we present the first realisation of such a double slit experiment by using correlated photons produced in type I Parametric Down Conversion. Our results confirm QM contradicting dBB predictions

On the Incompatibility of Standard Quantum Mechanics and the de Broglie-Bohm Theory

It is shown that the de Broglie-Bohm quantum theory of multi-particle systems is incompatible with the standard quantum theory of such systems unless the former is ergodic. A realistic experiment is suggested to distinguish between the two theories.Comment: A few technical changes incorporated in section V without any change in conclusion

Two-particle interference in standard and Bohmian quantum mechanics

The compatibility of standard and Bohmian quantum mechanics has recently been challenged in the context of two-particle interference, both from a theoretical and an experimental point of view. We analyze different setups proposed and derive corresponding exact forms for Bohmian equations of motion. The equations are then solved numerically, and shown to reproduce standard quantum-mechanical results.Comment: Minor corrections, 2 references added, version to appear in J. Phys.

Endogenous Quasicycles and Stochastic Coherence in a Closed Endemic Model

We study the role of demographic fluctuations in typical endemics as exemplified by the stochastic SIRS model. The birth-death master equation of the model is simulated using exact numerics and analysed within the linear noise approximation. The endemic fixed point is unstable to internal demographic noise, and leads to sustained oscillations. This is ensured when the eigenvalues ($\lambda$) of the linearised drift matrix are complex, which in turn, is possible only if detailed balance is violated. In the oscillatory state, the phases decorrelate asymptotically, distinguishing such oscillations from those produced by external periodic forcing. These so-called quasicycles are of sufficient strength to be detected reliably only when the ratio $|Im(\lambda)/Re(\lambda)|$ is of order unity. The coherence or regularity of these oscillations show a maximum as a function of population size, an effect known variously as stochastic coherence or coherence resonance. We find that stochastic coherence can be simply understood as resulting from a non-monotonic variation of $|Im(\lambda)/Re(\lambda)|$ with population size. Thus, within the linear noise approximation, stochastic coherence can be predicted from a purely deterministic analysis. The non-normality of the linearised drift matrix, associated with the violation of detailed balance, leads to enhanced fluctuations in the population amplitudes.Comment: 21 pages, 8 figure

Review of recent experimental progresses in Foundations of Quantum Mechanics and Quantum Information obtained in Parametric Down Conversion Experiments at IENGF

We review some recent experimental progresses concerning Foundations of Quantum Mechanics and Quantum Information obtained in Quantum Optics Laboratory "Carlo Novero" at IENGF. More in details, after a short presentation of our polarization entangled photons source (based on precise superposition of two Type I PDC emission) and of the results obtained with it, we describe an innovative double slit experiment where two degenerate photons produced by PDC are sent each to a specific slit. Beyond representing an interesting example of relation between visibility of interference and "welcher weg" knowledge, this configuration has been suggested for testing de Broglie-Bohm theory against Standard Quantum Mechanics. Our results perfectly fit SQM results, but disagree with dBB predictions. Then, we discuss a recent experiment addressed to clarify the issue of which wave-particle observables are really to be considered when discussing wave particle duality. This experiments realises the Agarwal et al. theoretical proposal, overcoming limitations of a former experiment. Finally, we hint to the realization of a high-intensity high-spectral-selected PDC source to be used for quantum information studies

Experimental tests of hidden variable theories from dBB to Stochastic Electrodynamics

In this paper we present some of our experimental results on testing hidden variable theories, which range from Bell inequalities measurements to a conclusive test of stochastic electrodynamics

Paediatric anatomical models in radiotherapy applications

Anatomical models have key applications in radiotherapy, notably to help understand the relationship between radiation dose and risk of developing side effects. This review analyses whether age-specific computational phantoms, developed from healthy subjects and paediatric cancer patient data, are adequate to model a paediatric population. The phantoms used in the study were International Commission on Radiological Protection (ICRP), 4D extended cardiac torso (XCAT) and Radiotherapy Paediatric Atlas (RT-PAL), which were also compared to literature data. Organ volume data for 19 organs was collected for all phantoms and literature. ICRP was treated as the reference for comparison, and percentage difference (P.D) for the other phantoms were calculated relative to ICRP. Overall comparisons were made for each age category (1, 5, 10, 15) and each organ. Statistical analysis was performed using Microsoft Excel (version 16.59). The smallest P.D to ICRP was for Literature (-17.4%), closely followed by XCAT (26.6%). The largest was for RT-PAL (88.1%). The rectum had the largest average P.D (1,049.2%) and the large bowel had the smallest (2.0%). The P.D was 122.6% at age 1 but this decreased to 43.5% by age 15. Linear regression analysis showed a correlation between organ volume and age to be the strongest for ICRP (R = 0.943) and weakest for XCAT (R = 0.676). The phantoms are similar enough to ICRP for potential use in modelling paediatric populations. ICRP and XCAT could be used to model a healthy population, whereas RT-PAL could be used for a population undergoing/after radiotherapy. [Abstract copyright: Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Democracy Matters: Lessons from the 2015 Citizens' Assemblies on English Devolution

The Citizens’ Assembly pilots on local democracy and devolution were the first of their kind in the United Kingdom. Organised by Democracy Matters — an alliance of university researchers and civil society organisations led by Professor Matthew Flinders — and funded by the UK’s Economic and Social Research Council, the Assemblies took place in Southampton and Sheffield towards the end of 2015

Bioactive IGF-1 release from collagen-GAG scaffold to enhance cartilage repair in vitro.

Tissue engineering is a promising technique for cartilage repair. Toward this goal, a porous collagen-glycosaminoglycan (CG) scaffold was loaded with different concentrations of insulin-like growth factor-1 (IGF-1) and evaluated as a growth factor delivery device. The biological response was assessed by monitoring the amount of type II collagen and proteoglycan synthesised by the chondrocytes seeded within the scaffolds. IGF-1 release was dependent on the IGF-1 loading concentration used to adsorb IGF-1 onto the CG scaffolds and the amount of IGF-1 released into the media was highest at day 4. This initial IGF-1 release could be modelled using linear regression analysis. Osteoarthritic (OA) chondrocytes seeded within scaffolds containing adsorbed IGF-1 deposited decorin and type II collagen in a dose dependent manner and the highest type II collagen deposition was achieved via loading the scaffold with 50 μg/ml IGF-1. Cells seeded within the IGF-1 loaded scaffolds also deposited more extracellular matrix than the no growth factor control group thus the IGF-1 released from the scaffold remained bioactive and exerted an anabolic effect on OA chondrocytes. The effectiveness of adsorbing IGF-1 onto the scaffold may be due to protection of the molecule from proteolytic digestion allowing a more sustained release of IGF-1 over time compared to adding multiple doses of exogenous growth factor. Incorporating IGF-1 into the CG scaffold provided an initial therapeutic burst release of IGF-1 which is beneficial in initiating ECM deposition and repair in this in vitro model and shows potential for developing this delivery device in vivo.EPSRC and Tigenix UK Limited, Byron House, Cambridge Business Park, Milton Road, Cambridge, are gratefully acknowledged for a studentship for L.M.M.This is the final published version. The final published version is available from Springer at http://link.springer.com/article/10.1007%2Fs10856-014-5325-y