Secure and efficient decoy-state quantum key distribution with inexact pulse intensities

We present a general theorem for the efficient verification of the lower bound of single-photon transmittance. We show how to do decoy-state quantum key distribution efficiently with large random errors in the intensity control. In our protocol, the linear terms of fluctuation disappear and only the quadratic terms take effect. We then show the unconditional security of decoy-state method with whatever error pattern in intensities of decoy pulses and signal pulses provided that the intensity of each decoy pulse is less than $\mu$ and the intensity of each signal pulse is larger than $\mu'$

Testing the decoy effect in the presence of store brands

Purpose – The purpose of this paper is to test decoy effect in the framework of sales promotion, by conducting several experiments to figure out how this decoy effect is influenced by the presence or absence of a store brand. Design/methodology/approach – Several experiments have been conducted to test the validity of the decoy effect and rule out some explanations for the changes in demand that take place. The experiments consider three brands (two national brands and one store brand). All the brand names and prices employed in the experiment are real. Findings – The results indicate that, as expected, the inclusion of a decoy in the choice set significantly increases the consumer’s relative preference for the promoted product; however, more importantly, the results also show that store brand consumers are more influenced by a decoy than national brand consumers. Originality/value – This paper presents the first evidence of the decoy effect in the presence of store brands

Passive decoy state quantum key distribution with practical light sources

Decoy states have been proven to be a very useful method for significantly enhancing the performance of quantum key distribution systems with practical light sources. While active modulation of the intensity of the laser pulses is an effective way of preparing decoy states in principle, in practice passive preparation might be desirable in some scenarios. Typical passive schemes involve parametric down-conversion. More recently, it has been shown that phase randomized weak coherent pulses (WCP) can also be used for the same purpose [M. Curty {\it et al.}, Opt. Lett. {\bf 34}, 3238 (2009).] This proposal requires only linear optics together with a simple threshold photon detector, which shows the practical feasibility of the method. Most importantly, the resulting secret key rate is comparable to the one delivered by an active decoy state setup with an infinite number of decoy settings. In this paper we extend these results, now showing specifically the analysis for other practical scenarios with different light sources and photo-detectors. In particular, we consider sources emitting thermal states, phase randomized WCP, and strong coherent light in combination with several types of photo-detectors, like, for instance, threshold photon detectors, photon number resolving detectors, and classical photo-detectors. Our analysis includes as well the effect that detection inefficiencies and noise in the form of dark counts shown by current threshold detectors might have on the final secret ket rate. Moreover, we provide estimations on the effects that statistical fluctuations due to a finite data size can have in practical implementations.Comment: 17 pages, 14 figure

Contextual effects and psychological features influencing decoy options: a review and research agenda

Objeto: El objetivo del artículo es desarrollar propuestas de investigación cuyos resultados contribuyan a la teoría existente sobre el efecto decoy Diseño/metodología: Primeramente, se presenta una revisión de la literatura sobre el efecto decoy y las interacciones con otros efectos contextuales que sean susceptibles de afectar a su funcionalidad. Después, se presentan dos propuestas de investigación: la introducción del doble decoy dentro de un mismo conjunto de opciones y el desempeño de opciones decoy bajo distintos niveles de fatiga cognitiva a lo largo de un proceso de compra. Aportaciones y resultados: En relación a la propuesta de investigación del doble decoy, se introducen distintas hipótesis acerca de su funcionamiento, generadas a partir de las distintas teorías existentes. Estas hipótesis predicen distintos comportamientos para el mismo diseño experimental. Este hecho reforzaría a al menos una de las vigentes explicaciones acerca del funcionamiento de opciones decoy. En relación a la proposición acerca del efecto decoy bajo distintos niveles de fatiga cognitiva, se esperan implicaciones relevantes para el diseño de procesos de compra que incorporen múltiples opciones, varios pasos a lo largo del proceso de compra u opciones complejas. Valor añadido: Ambas propuestas de investigación tienen como objetivo contribuir y mejorar la teoría existente sobre opciones decoy. Además, ambas aportarán información importante de cara al uso real de opciones decoy en procesos de compra.Purpose: The purpose of this paper is to develop future research proposals aiming to contribute the extant theory which explains decoy effects. Design/methodology/approach: Firstly, a review of the existing literature about decoy options and its interactions with contextual effects that could affect their performance is presented. Next, two research proposals are presented: the introduction of a double decoy choice set and the evaluation of decoy effect under different levels of cognitive effort in a purchasing process. Findings and Originality/value: For the research proposal concerning double decoy choice sets, different hypothesis are introduced based on the different theories aiming to explain the effect of simple decoy choice sets. This hypothesis predict different outcomes for the same experimental design, fact that could provide further support for at least one of the current explanations for decoy effects. Regarding the effect of decoy options under different levels of cognitive effort, implications for experimental design for sequential purchasing process are expected. Especially for those designed with complex options, with many steps or high number of options. Originality/value: Two new research proposal approaches are presented in order enhance the current theory. Moreover, both have managerial implications concerning the real usage of decoy options in reduced choice sets as well as in sequential purchasing processes.Peer Reviewe

Finite-key analysis of a practical decoy-state high-dimensional quantum key distribution

Compared with two-level quantum key distribution (QKD), highdimensional QKD enable two distant parties to share a secret key at a higher rate. We provide a finite-key security analysis for the recently proposed practical highdimensional decoy-state QKD protocol based on time-energy entanglement. We employ two methods to estimate the statistical fluctuation of the postselection probability and give a tighter bound on the secure-key capacity. By numerical evaluation, we show the finite-key effect on the secure-key capacity in different conditions. Moreover, our approach could be used to optimize parameters in practical implementations of highdimensional QKD

Inconclusive quantum measurements and decisions under uncertainty

We give a mathematical definition for the notion of inconclusive quantum measurements. In physics, such measurements occur at intermediate stages of a complex measurement procedure, with the final measurement result being operationally testable. Since the mathematical structure of Quantum Decision Theory has been developed in analogy with the theory of quantum measurements, the inconclusive quantum measurements correspond, in Quantum Decision Theory, to intermediate stages of decision making in the process of taking decisions under uncertainty. The general form of the quantum probability for a composite event is the sum of a utility factor, describing a rational evaluation of the considered prospect, and of an attraction factor, characterizing irrational, subconscious attitudes of the decision maker. Despite the involved irrationality, the probability of prospects can be evaluated. This is equivalent to the possibility of calculating quantum probabilities without specifying hidden variables. We formulate a general way of evaluation, based on the use of non-informative priors. As an example, we suggest the explanation of the decoy effect. Our quantitative predictions are in very good agreement with experimental data.Comment: Latex file, 16 page

Life-history and hormonal control of aggression in black redstarts: blocking testosterone does not decrease territorial aggression, but changes the emphasis of vocal behaviours during simulated territorial intrusions

Introduction: Many studies in behavioural endocrinology attempt to link territorial aggression with testosterone, but the exact relationship between testosterone and territorial behaviour is still unclear and may depend on the ecology of a species. The degree to which testosterone facilitates territorial behaviour is particularly little understood in species that defend territories during breeding and outside the breeding season, when plasma levels of testosterone are low. Here we suggest that species that defend territories in contexts other than reproduction may have lost the direct regulation of territorial behaviour by androgens even during the breeding season. In such species, only those components of breeding territoriality that function simultaneously as sexually selected signals may be under control of sex steroids.<p></p> Results: We investigated black redstarts (Phoenicurus ochruros), a species that shows periods of territoriality within and outside of the breeding season. We treated territorial males with an anti-androgen and an aromatase inhibitor during the breeding season to block both the direct and indirect effects of testosterone. Three and ten days after the treatment, implanted males were challenged with a simulated territorial intrusion. The treatment did not reduce the overall territorial response, but it changed the emphasis of territoriality: experimental males invested more in behaviours addressed directly towards the intruder, whereas placebo-treated males put most effort into their vocal response, a component of territoriality that may be primarily directed towards their mating partner rather than the male opponent.<p></p> Conclusions: In combination with previous findings, these data suggest that overall territoriality may be decoupled from testosterone in male black redstarts. However, high levels of testosterone during breeding may facilitate-context dependent changes in song