The time as an emergent property of quantum mechanics, a synthetic description of a first experimental approach

The "problem of time" in present physics substantially consists in the fact that a straightforward quantization of the general relativistic evolution equation and constraints generates for the Universe wave function the Wheeler-De Witt equation, which describes a static Universe. Page and Wootters considered the fact that there exist states of a system composed by entangled subsystems that are stationary, but one can interpret the component subsystems as evolving: this leads them to suppose that the global state of the universe can be envisaged as one of this static entangled state, whereas the state of the subsystems can evolve. Here we synthetically present an experiment, based on PDC polarization entangled photons, that allows showing with a practical example a situation where this idea works, i.e. a subsystem of an entangled state works as a "clock" of another subsystem

Bell measurements as a witness of a dualism in entanglement

We show how a property of dualism, which can exist in the entanglement of identical particles, can be tested in the usual photonic Bell measurement apparatus with minor modifications. Two different sets of coincidence measurements on the same experimental setup consisting of a Hong-Ou-Mandel interferometer demonstrate how the same two-photon state can emerge entanglement in the polarization or the momentum degree of freedom depending on the dynamical variables used for labeling the particles. Our experiment demonstrates how the same source can be used as both a polarization entangled state, as well as a dichotomic momentum entangled state shared between distant users Alice and Bob in accordance to which sets of detectors they access. When the particles become distinguishable by letting the information about one of the variables to be imprinted in yet another (possibly inaccessible) system or degree of freedom, the feature of dualism is expected to vanish. We verify this feature by polarization decoherence (polarization information in environment) or arrival time difference, which both respectively destroy one of the dual forms of entanglement.Comment: 5 pages, 4 figure

Exploring Quantum Correlations from Discord to Entanglement

Quantum correlations represent a fundamental tool for studies ranging from basic science to quantum technologies. Different non-classical correlations have been identified and studied, as entanglement and discord. In this Paper we explore experimentally the rich geometry of polarization Bell-diagonal states. By taking advantage of the statistical method of generation, the values of entanglement and discord along different trajectories in the space of the parameters of density matrix have been measured. The effects of sudden death of entanglement and complete "freeze" of discord were investigated in order to detect the domains with different domination of one type of quantum correlation against to other. A geometric interpretation for each considered phenomena is addressed. The observed good agreement between experiment and theory for all investigated trajectories ensures the reliability of this method

Statistical Estimation of Quantum Tomography Protocols Quality

A novel operational method for estimating the efficiency of quantum state tomography protocols is suggested. It is based on a-priori estimation of the quality of an arbitrary protocol by means of universal asymptotic fidelity distribution and condition number, which takes minimal value for better protocol. We prove the adequacy of the method both with numerical modeling and through the experimental realization of several practically important protocols of quantum state tomography

Anisotropically high entanglement of biphotons generated in spontaneous parametric down conversion

We show that the wave packet of a biphoton generated via spontaneous parametric down conversion is strongly anisotropic. Its anisotropic features manifest themselves very clearly in comparison of measurements performed in two different schemes: when the detector scanning plane is perpendicular or parallel to the plane containing the crystal optical axis and the laser axis. The first of these two schemes is traditional whereas the second one gives rise to such unexpected new results as anomalously strong narrowing of the biphoton wave packet measured in the coincidence scheme and very high degree of entanglement. The results are predicted theoretically and confirmed experimentally

Direct experimental observation of nonclassicality in ensembles of single photon emitters

In this work we experimentally demonstrate for the first time a recently proposed criterion adressed to detect nonclassical behavior in the fluorescence emission of ensembles of single-photon emitters. In particular, we apply the method to study clusters of NV centres in diamond observed via single-photon-sensitive confocal microscopy. Theoretical considerations on the behavior of the parameter at any arbitrary order in presence of poissonian noise are presented and, finally, the opportunity of detecting manifold coincidences is discussed

БИЗНЕС-МОДЕЛЬ И ЕЕ РОЛЬ В РАЗРАБОТКЕ ИННОВАЦИОННОЙ ПОЛИТИКИ (АНАЛИЗ ЗАРУБЕЖНЫХ КОНЦЕПЦИЙ)

Nowadays, the development of an effective innovation policy is one of the priority issues of the socioeconomic development of Russia and many other countries. However, despite the efforts made, not all of them succeeded in its solution. In Russia, like in a number of other states, the expert community continue to search  or effective ways to influence microeconomic entities and, above all, businesses that would yield an adequate response. Therefore, any attempt to reveal structures which, when affected, would lead to the increase in the innovative activity of commercial organizations, are not only of theoretical but also of great practical interest. The paper analyzes proposals of foreign authors on the solution of this problem. The foreign approaches under study are focused on the recognition of the business model as a special component of commercial organizations. Its specifics should be taken into account in development and implementation of the state innovation policy in relation to business. As part of a general critical analysis of the approaches, the author summarized and systematized the existing views on the contents of business models, their types and relationships with innovations in organizations. At present, there is no common understanding in the literature that the choice of particular types of business models determining different sources of innovative activity in response to the corresponding state policy requires a prudent attitude and preliminary clarification of a number of additional conditions. The most significant of these include the type of a business model, the stability of its reproduction and position in the industry markets. The conclusions made in the paper require that new important areas of theoretical research into the domestic economy should be developed. They should be directed towards the determination of business model types in different economic sectors, their stability and development of a corresponding state innovation course with respect to them. Along with above, these conclusions lay the foundations for practical efforts to implement innovative strategies developed for enterprizes with different types of business models.В настоящее время среди первоочередных проблем общественно-экономического развития России и многих других стран стоит вопрос о разработке эффективной инновационной политики. Однако несмотря на предпринимаемые усилия, многим пока не удается решить его. В нашей стране, как и в целом ряде других государств, ученые и практики продолжают вести поиски результативных способов воздействия на микроэкономические субъекты, и в первую очередь на бизнес, которые бы вызвали адекватный ответ. Поэтому попытки выявить те структуры, влияние на которые обеспечило бы повышение инновационной активности коммерческих организаций, представляют не только теоретический, но и большой практический интерес. Анализу предложений зарубежных авторов по решению этого вопроса посвящена настоящая статья. В центре внимания исследуемых подходов иностранных ученых лежало признание бизнес-модели как специфического элемента коммерческих организаций, особенности которого следует непременно учитывать при разработке и реализации государственной инновационной политики в отношении бизнеса. В рамках общего критического анализа подходов автор обобщил и систематизировал имеющиеся взгляды на содержание бизнес-моделей, их типы и связи с инновациями в организациях. В настоящее время по данному вопросу в специальной литературе еще не сложилось однозначного понимания, что обращение к разным типам бизнес-моделей как обусловливающим разные источники инновационной активности в ответ на соответствующую государственную политику требует осмотрительного отношения и предварительного выяснения целого ряда дополнительных условий. К наиболее существенным из них относятся тип бизнес-модели, стабильность ее воспроизводства и положения на отраслевых рынках. Сделанные в статье выводы заставляют обратиться к новым важным направлениям теоретических исследований отечественной экономики, касающихся определения типов бизнес-моделей в разных экономических секторах, их устойчивости и разработки соответствующего государственного инновационного курса по отношению к ним. Вместе с тем эти выводы закладывают основы и для практических усилий по реализации инновационных стратегий, разработанных в отношении производств с разными типами бизнес-моделей

Native NIR-emitting single colour centres in CVD diamond

Single-photon sources are a fundamental element for developing quantum technologies, and sources based on colour centres in diamonds are among the most promising candidates. The well-known NV centres are characterized by several limitations, thus few other defects have recently been considered. In the present work, we characterize in detail native efficient single colour centres emitting in the near infra-red in both standard IIa single-crystal and electronic-grade polycrystalline commercial CVD diamond samples. In the former case, a high-temperature annealing process in vacuum is necessary to induce the formation/activation of luminescent centres with good emission properties, while in the latter case the annealing process has marginal beneficial effects on the number and performances of native centres in commercially available samples. Although displaying significant variability in several photo physical properties (emission wavelength, emission rate instabilities, saturation behaviours), these centres generally display appealing photophysical properties for applications as single photon sources: short lifetimes, high emission rates and strongly polarized light. The native centres are tentatively attributed to impurities incorporated in the diamond crystal during the CVD growth of high-quality type IIa samples, and offer promising perspectives in diamond-based photonics.Comment: 27 pages, 10 figures. Submitted to "New Journal of Phsyics", NJP-100003.R