Quantum correlations of twophoton polarization states in the parametric down-conversion process

We consider correlation properties of twophoton polarization states in the parametric down-conversion process. In our description of polarization states we take into account the simultaneous presence of colored and white noise in the density matrix. Within the considered model we study the dependence of the von Neumann entropy on the noise amount in the system and derive the separability condition for the density matrix of twophoton polarization state, using Perec-Horodecki criterion and majorization criterion. Then the dependence of the Bell operator (in CHSH form) on noise is studied. As a result, we give a condition for determining the presence of quantum correlation states in experimental measurements of the Bell operator. Finally, we compare our calculations with experimental data [doi:10.1103/PhysRevA.73.062110] and give a noise amount estimation in the photon polarization state considered there.Comment: 10 pages, 7 figures; corrected typo

Quantum teleportation of a single-photon wave packet

A quantum teleportation scheme based on the EPR-pair entangled with respect to the ``energy+time'' variables is proposed. Teleportation of the multimode state of a single-photon wave packet is considered.Comment: 6 pages, no figure

Imperfect Detectors in Linear Optical Quantum Computers

We discuss the effects of imperfect photon detectors suffering from loss and noise on the reliability of linear optical quantum computers. We show that for a given detector efficiency, there is a maximum achievable success probability, and that increasing the number of ancillary photons and detectors used for one controlled sign flip gate beyond a critical point will decrease the probability that the computer will function correctly. We have also performed simulations of some small logic gates and estimate the efficiency and noise levels required for the linear optical quantum computer to function properly.Comment: 13 pages, 5 figure

Measurement in Quantum Physics

The conceptual problems in quantum mechanics -- related to the collapse of the wave function, the particle-wave duality, the meaning of measurement -- arise from the need to ascribe particle character to the wave function. As will be shown, all these problems dissolve when working instead with quantum fields, which have both wave and particle character. Otherwise the predictions of quantum physics, including Bell's inequalities, coincide with those of the standard treatments. The transfer of the results of the quantum measurement to the classical realm is also discussed.Comment: 34 pages, in Latex, revised and expanded version with an extra appendix on decoherenc

Jump Diffusion Outperforms Geometric Brownian Motion When Forecasting BRIC’s Daily Foreign Exchange Carry Trading Strategy Returns

This research will examine how the Jump Diffusion Model 1 (JDM) accurately outperforms Geometric Brownian Motion2 (GBM) when forecasting the Japanese Yen carry trade daily returns for the BRICs\u27 and three bellwether currency pairs GBP/JPY, EUR/JPY, and PLN/JPY from January 2, 2012, to September 30, 2023. An added innovation within this research is the inclusion of the interest rate return in arriving at the daily cumulative carry trade returns. This is a distinctive and unique feature that offers a different perspective, since many journal articles do not discuss or address the interest earned (long position) component of the FX Carry trade. The focus of this paper will be on the uncovered interest rate parity. This research will comprehensively evaluate multiple regression modeling for the (JDM) and (GBM) in isolation, mean reversion, volatility, plus back-testing forecasted versus actual total dollar returns within in and out ofsample time series for both models

Experimental scheme for quantum teleportation of a single-photon packet

Both complete protocol and optical setup for experimental realization of quantum teleportation of unknown single-photon wave packet are proposed.Comment: 7 pages, 1 figure (under request

Pandemic Signage

Our exhibit engages with a number of distinct themes, and this thematic range reflects the evolution of our inquiry and points of exploration. However, the common thread that ties our exhibit together is public communication. We have centered local institutions in this exhibit, and we hope through exploring our collection you will feel encouraged to consider how COVID-19 has changed the way communities and institutions interact, and howthis interaction, in turn, has changed how we experience the pandemic. Moreover, we hope you will come to consider how these shifts in both method and content of communication are made manifest in the public spaces we all inhabit, in diverse and dynamic ways. Our definition of institution is quite broad, as is our definition of community, and we encourage you to ponder what differentiates one from the other.https://digitalcommons.carleton.edu/covid19archive_exhibits/1003/thumbnail.jp

Intersectional stigma and the non-communicable disease syndemic in the context of HIV: protocol for a multisite, observational study in the USA

IntroductionThe increasing burden of non-communicable diseases, such as hypertension, diabetes and dyslipidaemia, presents key challenges to achieving optimal HIV care outcomes among ageing people living with HIV. These diseases are often comorbid and are exacerbated by psychosocial and structural inequities. This interaction among multiple health conditions and social factors is referred to as a syndemic. In the USA, there are substantial disparities by social position (ie, racial, ethnic and socioeconomic status) in the prevalence and/or control of non-communicable diseases and HIV. Intersecting stigmas, such as racism, classism and homophobia, may drive these health disparities by contributing to healthcare avoidance and by contributing to a psychosocial syndemic (stress, depression, violence victimisation and substance use), reducing success along the HIV and non-communicable disease continua of care. Our hypothesis is that marginalised populations experience disparities in non-communicable disease incidence, prevalence and control, mediated by intersectional stigma and the psychosocial syndemic.Methods and analysisCollecting data over a 4 year period, we will recruit sexual minority men (planned n=1800) enrolled in the MACS/WIHS Combined Cohort Study, a long-standing mixed-serostatus observational cohort in the USA, to investigate the following specific aims: (1) assess relationships between social position, intersectional stigma and the psychosocial syndemic among middle-aged and ageing sexual minority men, (2) assess relationships between social position and non-communicable disease incidence and prevalence and (3) assess relationships between social position and HIV and non-communicable disease continua of care outcomes, mediated by intersectional stigma and the psychosocial syndemic. Analyses will be conducted using generalised structural equation models using a cross-lagged panel model design.Ethics and disseminationThis protocol is approved as a single-IRB study (Advarra Institutional Review Board: Protocol 00068335). We will disseminate results via peer-reviewed academic journals, scientific conferences, a dedicated website, site community advisory boards and forums hosted at participating sites