Local Quantum Measurement and No-Signaling Imply Quantum Correlations

We show that, assuming that quantum mechanics holds locally, the finite speed of information is the principle that limits all possible correlations between distant parties to be quantum mechanical as well. Local quantum mechanics means that a Hilbert space is assigned to each party, and then all local positive-operator-valued measurements are (in principle) available; however, the joint system is not necessarily described by a Hilbert space. In particular, we do not assume the tensor product formalism between the joint systems. Our result shows that if any experiment would give nonlocal correlations beyond quantum mechanics, quantum theory would be invalidated even locally.Comment: Published version. 5 pages, 1 figure

Promoting weight-loss via smartphone health applications (MyFitnessPal)

Obesity has become a public health crisis in the United States. 68% of men and 64% of women in the United States are considered overweight or obese. Obesity is being addressed through a variety of strategies, the use of mobile apps is a relatively new development that could prove useful in helping people to develop healthy dietary habits. Tracking the consumption of certain foods and drinks may potentially help individuals achieve an improved understanding of their dietary patterns. The goal of this project was to develop and provide educational materials on the use of MyFitnessPal to patients seeking dietary advice.https://scholarworks.uvm.edu/fmclerk/1660/thumbnail.jp

Gendered Self-Concepts and Drinking Behavior in a National Sample of Emerging Adults

Despite evidence that males drink more than females, there is much to be learned about gendered explanations for sex differences in alcohol use. We use the National Longitudinal Study of Adolescent to Adult Health data to investigate gendered self-concept as related to alcohol use and related consequences among a sample of emerging adults. Dominance Masculinity (e.g., being aggressive, forceful, dominant) was the most consistent predictor of alcohol-related outcomes for both males and females. Endorsement of feminine characteristics (e.g., compassion, understanding, sympathetic) was protective against binge drinking and social consequences for males whereas endorsement of general masculine characteristics (e.g., independent, assertive, leader) protected against social consequences for females

Discord and non-classicality in probabilistic theories

Quantum discord quantifies non-classical correlations in quantum states. We introduce discord for states in causal probabilistic theories, inspired by the original definition proposed in Ref. [17]. We show that the only probabilistic theory in which all states have null discord is classical probability theory. Non-null discord is then not just a quantum feature, but a generic signature of non-classicality.Comment: 5 pages, revtex styl

A violation of the uncertainty principle implies a violation of the second law of thermodynamics

Uncertainty relations state that there exist certain incompatible measurements, to which the outcomes cannot be simultaneously predicted. While the exact incompatibility of quantum measurements dictated by such uncertainty relations can be inferred from the mathematical formalism of quantum theory, the question remains whether there is any more fundamental reason for the uncertainty relations to have this exact form. What, if any, would be the operational consequences if we were able to go beyond any of these uncertainty relations? We give a strong argument that justifies uncertainty relations in quantum theory by showing that violating them implies that it is also possible to violate the second law of thermodynamics. More precisely, we show that violating the uncertainty relations in quantum mechanics leads to a thermodynamic cycle with positive net work gain, which is very unlikely to exist in nature.Comment: 8 pages, revte

Compressibility of Mixed-State Signals

We present a formula that determines the optimal number of qubits per message that allows asymptotically faithful compression of the quantum information carried by an ensemble of mixed states. The set of mixed states determines a decomposition of the Hilbert space into the redundant part and the irreducible part. After removing the redundancy, the optimal compression rate is shown to be given by the von Neumann entropy of the reduced ensemble.Comment: 7 pages, no figur

Generalization of entanglement to convex operational theories: Entanglement relative to a subspace of observables

We define what it means for a state in a convex cone of states on a space of observables to be generalized-entangled relative to a subspace of the observables, in a general ordered linear spaces framework for operational theories. This extends the notion of ordinary entanglement in quantum information theory to a much more general framework. Some important special cases are described, in which the distinguished observables are subspaces of the observables of a quantum system, leading to results like the identification of generalized unentangled states with Lie-group-theoretic coherent states when the special observables form an irreducibly represented Lie algebra. Some open problems, including that of generalizing the semigroup of local operations with classical communication to the convex cones setting, are discussed.Comment: 19 pages, to appear in proceedings of Quantum Structures VII, Int. J. Theor. Phy

Optimal Quantum Cloning Machines

We present Quantum Cloning Machines (QCM) that transform N identical qubits into $M>N$ identical copies and we prove that the fidelity (quality) of these copies is optimal. The connection between cloning and measurement is discussed in detail. When the number of clones M tends towards infinity, the fidelity of each clone tends towards the optimal fidelity that can be obtained by a measurement on the input qubits. More generally, the QCM are universal devices to translate quantum information into classical information.Comment: 4 pages, Latex, 1 postscript figure, (very) minor modification

The other side of the coin: Exploring the effects of adolescent delinquency on young adult self-control

Purpose Although there is robust support for low self-control as a predictor of delinquent behavior, the question of whether delinquent behavior impacts self-control has been largely ignored. We ask, after accounting for baseline group differences in impulsivity and self-control, can delinquency be associated with later group differences in self-control? Methods Utilizing data from the National Longitudinal Study of Adolescent to Adult Health we employed propensity score matching to create comparable groups (i.e., on self-control and other delinquency correlates) of youth who did and did not participate in delinquent behavior in adolescence and compared them on self-control and impulsivity in later waves. Results Despite baseline similarity, the groups identified as delinquent at Wave II differed significantly from non-delinquent groups on self-control and impulsivity at Waves III and IV. Both groups experienced improvement in self-control and impulsivity over time though improvement was more marked for the non-delinquent youth. Conclusions We have established preliminary evidence that delinquent behavior may be associated with later levels of self-control. Participation in delinquency may remove youth from normal developmental patterns in which self-control strengthens over time. Future research should attempt to replicate our findings and determine the specific mechanisms through which delinquent behavior may impact later self-control

No Signalling and Quantum Key Distribution

Standard quantum key distribution protocols are provably secure against eavesdropping attacks, if quantum theory is correct. It is theoretically interesting to know if we need to assume the validity of quantum theory to prove the security of quantum key distribution, or whether its security can be based on other physical principles. The question would also be of practical interest if quantum mechanics were ever to fail in some regime, because a scientifically and technologically advanced eavesdropper could perhaps use post-quantum physics to extract information from quantum communications without necessarily causing the quantum state disturbances on which existing security proofs rely. Here we describe a key distribution scheme provably secure against general attacks by a post-quantum eavesdropper who is limited only by the impossibility of superluminal signalling. The security of the scheme stems from violation of a Bell inequality.Comment: Clarifications and minor revisions in response to comments. Final version; to appear in Phys. Rev. Let