When faced with Duhemian problems of underdetermination, scientific method suggests neither a circumvention of such difficulties via the uncritical acceptance of background assumptions, nor the employment of epistemically unsatisfying subjectivist models of rational retainment. Instead, scientists are challenged to attack problems of underdetermination 'head-on', through a careful analysis of the severity of the testing procedures responsible for the production and modeling of their anomalous data. Researchers faced with the task of explaining empirical anomalies, employ a number of diverse and clever experimental techniques designed to cut through the Duhemian mists, and account for potential sources of error that might weaken an otherwise warranted inference. In lieu of such progressive experimental procedures, scientists try to identify the actual inferential work that an existing experiment is capable of providing so as to avoid ascribing to its output more discriminative power than it is rightfully due. We argue that the various strategies adopted by researchers involved in the testing of Bell's inequality, are well represented by Mayo's error-statistical notion of scientific evidence. In particular, an acceptance of her stringent demand for the output of severe tests to stand at the basis of rational inference, helps to explain the methodological reactions expressed by scientists in response to the loopholes that plagued the early Bell experiments performed by Alain Aspect et al.. At the same time, we argue as a counterpoint, that these very reactions present a challenge for 'top-down' approaches to Duhem's problem. / Master of Arts

This thesis investigates the violation of Bell's Inequality through the use of nonlocal measurement schemes as encapsulated in a quasi-deterministic toy model. This toy model, called the Q Box, is reminiscent of Mermin's Box in that it describes a system that appears to be deterministic yet produces the statistics of a quantum type system. [1] The workings of the Q Box are detailed both as a thought experiment and as a computer simulation. Nonlocal measurement protocols similar to those which generate a violation of Bell's Inequality in the Q Box are also applied to Mermin's Box, with comparable results. [1] N.D. Mermin, "Bringing home the atomic world: Quantum mysteries for anybody," Am. J. Phys. 49: 940-943 (1981). N. David Mermin, Am. J. Phys. 58:731-734 (1990).

Theoretical work in quantum information has demonstrated that a classical hidden-variable model of an entangled singlet state can explain nonclassical correlations observed in tests of Bell’s inequality if while measuring the Bell correlation, the underlying probability distribution of the hidden-variable changes depending on the measurement basis. To rule out this possibility, distant quasars can be utilized as random number generators to set measurement bases in an experimental test of Bell’s inequality. Here we report on the design and characterization of a device that uses the color of incoming quasar photons to output a random bit with nanosecond latency. Through the 1-meter telescope at JPL Table Mountain Observatory, we observe and generate random bits from quasars with redshifts z = 0.1−3.9. In addition, we formulate a mathematical model that quantifies the fidelity of the bits generated.

Ce manuscrit décrit des expériences d’optique atomique quantique utilisant un détecteur résolu en impulsions d’atomes uniques d’hélium métastable. La première partie du manuscrit décrit la mesure de cohérence de deuxième ordre de la superradiance à partir d’un condensat de Bose-Einstein d’helium métastable. Bien que le condensat soit cohérent et le gain du processus de superradiance élevé, celle-ci montre toujours une statistique thermique comme celle de l’émission spontanée. La suite du manuscrit est dédiée au test de la non localité d’une source atomique corrélée en impulsion. Le schéma du test s’inspire d’une réalisation faite par Rarity et Tapster sur des photons intriqués en impulsion. Les ingrédients principaux d’un tel schéma sont la source atomique générée par instabilité dynamique du condensat dans un réseau optique en mouvement, le contrôle cohérent des atomes par diffraction de Bragg et la mesure de la corrélation des atomes dans les différentes voies de sortie du schéma interférométrique. Un point clé est le contrôle et la manipulation de la phase des ondes atomiques. Le chapitre 3 décrit les tests sur le contrôle cohérent par diffraction de Bragg et leurs résultats encourageants. La nature non classique de notre source atomique est démontrée par l’observation d’une interférence à deux particules en les envoyant sur une séparatrice atomique. Cet analogue atomique de l’expérience de Hong Ou et Mandel est le sujet du dernier chapitre de ce manuscrit. Le résultat de cette expérience ouvre la possibilité du test d’inégalité de Bell avec des particules massives corrélées sur des degrés de liberté externe. / This manuscript describes quantum atom optics experiments using metastable helium atoms with a single-atom momentum resolved detector. In the first part of this manuscript, the second order correlation measurement of the superradiance from a metastable helium Bose-Einstein condensate is presented. The superradiance effect is the collective radiation of dense ensemble where a strong gain of the radiation is expected. We have shown the thermal like statistics of the emission even in the presence of the strong gain. The next part of the manuscript is devoted to the quantum nonlocality test using a pair of atoms entangled in momentum. The protocol we came up with is inspired from the one of Rarity and Tapster with pairs of photons entangled in momentum. The essential ingredients of this protocol are the atomic pair produced by dynamical instability of the Bose-Einstein condensate in a moving optical lattice, the coherent control of the atomic pair by Bragg diffraction and the correlation measurement of the atoms in different output modes of the interferometric protocol. The experimental characterization and preparation of coherent control by Bragg diffraction are presented showing the proof of principle of such a protocol. The last part of the manuscript discusses the realization of the atomic Hong-Ou-Mandel experiment using the same atomic pair with an atomic beamsplitter. The non-classical interference result of this experiment has opened an opportunity for us to realize Bell’s inequality test with massive particles correlated in external degrees of freedom.