Fundamental Tests of Quantum Mechanics using Two-Photon Entanglement

In this thesis, we experimentally test fundamental properties of quantum mechanics, namely non-locality (in the form of three new families of Bell's inequalities) and the symmetry of envariance. To accomplish these we use a Sagnac source of polarization entangled photon pairs. In chapters one and two we discuss the relevant background information in quantum information theory, nonlinear optics, experimental realization of polarization entangled photons and a trouble-shooting and maintenance guide for a Saganc source. In chapter three we experiment with a set of three newly derived families of Bell's inequalities. These three families are predicted to yield the largest volume of violation of the local hidden variable models (LHVM). Our experimental results are in good agreement with those predictions and therefore, represent the largest volume of experimental violation of LHVM to date. We showed a violation of up to 30 sigma from what is predicted by LHVM, and our results followed closely to the predictions of quantum mechanics. In chapter four we experimentally test envariance, an assisted-symmetry exhibited by specifi c quantum systems. Envariance is a fundamental property in the quantum world that has lacked, until now, extensive experimental study. The symmetry has ramifi cations in the foundations of quantum mechanics, and plays an integral role in a proof of Born's rule [1]. Our results serve as a benchmark the property of envariance. We show that experimental quantum states can be (99.66+/- 0.04)% envariant over a wide range of transformations, as measured using the average quantum fi delity [2], and (99.963 +/- 0.005)% as measured using a modifi ed average Bhattacharya Coeffi cient [3], a measure of the overlap of two probability distributions

Experimental nonlocal and surreal Bohmian trajectories

Weak measurement allows one to empirically determine a set of average trajectories for an ensemble of quantum particles. However, when two particles are entangled, the trajectories of the first particle can depend nonlocally on the position of the second particle. Moreover, the theory describing these trajectories, called Bohmian mechanics, predicts trajectories that were at first deemed “surreal” when the second particle is used to probe the position of the first particle. We entangle two photons and determine a set of Bohmian trajectories for one of them using weak measurements and postselection. We show that the trajectories seem surreal only if one ignores their manifest nonlocality.Full Tex

Pregnant Women's Perceptions of Harms and Benefits of Mental Health Screening.

BACKGROUND:A widely held concern of screening is that its psychological harms may outweigh the benefits of early detection and treatment. This study describes pregnant women's perceptions of possible harms and benefits of mental health screening and factors associated with identifying screening as harmful or beneficial. METHODS:This study analyzed a subgroup of women who had undergone formal or informal mental health screening from our larger multi-site, cross-sectional study. Pregnant women >16 years of age who spoke/read English were recruited (May-December 2013) from prenatal classes and maternity clinics in Alberta, Canada. Descriptive statistics were generated to summarize harms and benefits of screening and multivariable logistic regression identified factors associated with reporting at least one harm or affirming screening as a positive experience (January-December 2014). RESULTS:Overall study participation rate was 92% (N = 460/500). Among women screened for mental health concerns (n = 238), 63% viewed screening as positive, 69% were glad to be asked, and 87% took it as evidence their provider cared about them. Only one woman identified screening as a negative experience. Of the 6 harms, none was endorsed by >7% of women, with embarrassment being most cited. Women who were very comfortable (vs somewhat/not comfortable) with screening were more likely to report it as a positive experience. LIMITATIONS:Women were largely Caucasian, well-educated, partnered women; thus, findings may not be generalizable to women with socioeconomic risk. CONCLUSIONS:Most women perceived prenatal mental health screening as having high benefit and low harm. These findings dispel popular concerns that mental health screening is psychologically harmful

Model fit indices for latent classes of depressive symptoms from pregnancy to one year postpartum.

<p>Model fit indices for latent classes of depressive symptoms from pregnancy to one year postpartum.</p

Descriptive statistics for maternal depression and child externalizing and internalizing behavior variables.

<p>Descriptive statistics for maternal depression and child externalizing and internalizing behavior variables.</p

Bivariate relationships between maternal depression trajectories and child externalizing and internalizing behavior outcomes.

<p>Bivariate relationships between maternal depression trajectories and child externalizing and internalizing behavior outcomes.</p

Bivariate and final multivariable logistic regression models predicting children’s externalizing behaviors (hyperactivity and inattention and physical aggression) at age three.

<p>Bivariate and final multivariable logistic regression models predicting children’s externalizing behaviors (hyperactivity and inattention and physical aggression) at age three.</p

Bivariate and final multivariable logistic regression model predicting children’s Internalizing behaviors (emotional/anxiety disorder and separation anxiety) at age three.

<p>Bivariate and final multivariable logistic regression model predicting children’s Internalizing behaviors (emotional/anxiety disorder and separation anxiety) at age three.</p