Limits on non-local correlations from the structure of the local state space

The outcomes of measurements on entangled quantum systems can be nonlocally correlated. However, while it is easy to write down toy theories allowing arbitrary nonlocal correlations, those allowed in quantum mechanics are limited. Quantum correlations cannot, for example, violate a principle known as macroscopic locality, which implies that they cannot violate Tsirelson's bound. This work shows that there is a connection between the strength of nonlocal correlations in a physical theory, and the structure of the state spaces of individual systems. This is illustrated by a family of models in which local state spaces are regular polygons, where a natural analogue of a maximally entangled state of two systems exists. We characterize the nonlocal correlations obtainable from such states. The family allows us to study the transition between classical, quantum, and super-quantum correlations, by varying only the local state space. We show that the strength of nonlocal correlations - in particular whether the maximally entangled state violates Tsirelson's bound or not - depends crucially on a simple geometric property of the local state space, known as strong self-duality. This result is seen to be a special case of a general theorem, which states that a broad class of entangled states in probabilistic theories - including, by extension, all bipartite classical and quantum states - cannot violate macroscopic locality. Finally, our results show that there exist models which are locally almost indistinguishable from quantum mechanics, but can nevertheless generate maximally nonlocal correlations.Comment: 26 pages, 4 figures. v2: Document structure changed. Main theorem has been extended. It applies to all quantum states now. v3: new abstrac

A quantum delayed choice experiment

Quantum systems exhibit particle-like or wave-like behaviour depending on the experimental apparatus they are confronted by. This wave-particle duality is at the heart of quantum mechanics, and is fully captured in Wheeler's famous delayed choice gedanken experiment. In this variant of the double slit experiment, the observer chooses to test either the particle or wave nature of a photon after it has passed through the slits. Here we report on a quantum delayed choice experiment, based on a quantum controlled beam-splitter, in which both particle and wave behaviours can be investigated simultaneously. The genuinely quantum nature of the photon's behaviour is tested via a Bell inequality, which here replaces the delayed choice of the observer. We observe strong Bell inequality violations, thus showing that no model in which the photon knows in advance what type of experiment it will be confronted by, hence behaving either as a particle or as wave, can account for the experimental data

Evaluability assessment: an application in a complex community improvement setting

Evaluation is essential to understand whether and how policies and other interventions work, why they sometimes fail, and whether they represent a good use of resources. Evaluability assessment (EA) is a means of collaboratively planning and designing evaluations, seeking to ensure they generate relevant and robust evidence that supports decision-making and contributes to the wider evidence base. This article reports on the context, the process undertaken and evidence from participants in an EA facilitated with public service workers involved in implementing a complex, area-based community improvement initiative. This is a novel context in which to conduct an EA. We show how the process allows practitioners at all levels to identify activities for evaluation and co-produce the theory of change developed through the EA. This enables evaluation recommendations to be developed that are relevant to the implementation of the programme, and which take account of available data and resources for evaluation

Artificial Intelligence and Intellectual Property Law: From Diagnosis to Action

The use of “artificial intelligence” systems becomes ever more widespread and far-reaching. Technological and economic concepts for an AI-based future are about to be implemented. It is, hence, time for the intellectual property system to develop answers to the challenges brought about by AI. Against this background, Zurich University’s Center for Intellectual Property and Competition Law (CIPCO) has initiated a joint research project on AI/IP with the Swiss Intellectual Property Institute (IPI). A first stage of this project has evaluated the state of the legal and economic discourse. These insights form the basis for policy recommendations on how the intellectual property system ought to be adapted to AI-related developments. The present paper describes – as draft work in progress – the project setup and summarizes its results gained so far. In doing so, it addresses key AI/IP issues, including business models of AI innovation leaders, inventorship/creatorship of AI systems de lege lata and de lege ferenda, the DABUS litigation, the discussion on whether new types of IP rights are necessary to protect AI inventions, the allocation of entitlements and liability regarding such innovations, AI-related revisions in the guidelines of important patent and trademark offices, the use such offices make of AI tools, the need for new protection carve-outs (e.g. to foster text and data mining), as well as AI’s potential raising the bar-effect. Der Einsatz von Systemen der „künstlichen Intelligenz“ wird immer verbreiteter und weitreichender. Viele technische und ökonomische Zukunftsszenarien stehen an der Schwelle zur Realisierung. Damit wird es auch für das Immaterialgüterrecht dringender, dort Antworten zu entwickeln, wo es sich durch KI herausgefordert sieht. Das Center for Intellectual Property and Competition Law (CIPCO) der Universität Zürich hat daher ein KI/IP-Kooperationsprojekt mit dem Schweizerischen Institut für Geistiges Eigentum (IGE) aufgenommen. Eine erste Projektphase hat den Stand des ökonomischen und rechtlichen Diskurses ermittelt und bildet damit die Grundlage für Empfehlungen zur künftigen Ausgestaltung des Immaterialgüterrechts in diesem Bereich. Der vorliegende Beitrag – bei dem es sich noch um einen weiterzuentwickelnden Entwurf handelt – legt hierüber Rechenschaft ab. Er beleuchtet nicht nur die Projektausgestaltung, sondern auch die gegenwärtigen KI/IP-Zentralthemen, etwa die Geschäftsmodelle von KI-Innovationsführern, Erfinder- bzw. Urheberschaft von KI-Systemen de lege lata und de lege ferenda, die Rechtsprechung zu DABUS, die Diskussion um die Notwendigkeit neuer Schutzrechte für KI-Innovationen, die Allokation von Rechtspositionen und Haftungsverantwortung an solchen Innovationen jenseits der Erfinder /Urheberfrage, die KI-bezogenen Neuerungen in den Leitlinien wichtiger Patent- und Markenämter sowie den Einsatz von KI-Instrumenten durch diese Ämter, neue Schutzschranken zur Förderung von KI und KI als Schutzhürden erhöhender Faktor

Experimental certification of millions of genuinely entangled atoms in a solid

Quantum theory predicts that entanglement can also persist in macroscopic physical systems, albeit difficulties to demonstrate it experimentally remain. Recently, significant progress has been achieved and genuine entanglement between up to 2900 atoms was reported. Here we demonstrate 16 million genuinely entangled atoms in a solid-state quantum memory prepared by the heralded absorption of a single photon. We develop an entanglement witness for quantifying the number of genuinely entangled particles based on the collective effect of directed emission combined with the nonclassical nature of the emitted light. The method is applicable to a wide range of physical systems and is effective even in situations with significant losses. Our results clarify the role of multipartite entanglement in ensemble-based quantum memories as a necessary prerequisite to achieve a high single-photon process fidelity crucial for future quantum networks. On a more fundamental level, our results reveal the robustness of certain classes of multipartite entangled states, contrary to, e.g., Schr\"odinger-cat states, and that the depth of entanglement can be experimentally certified at unprecedented scales.Comment: 11 pages incl. Methods and Suppl. Info., 4 figures, 1 table. v2: close to published version. See also parallel submission by Zarkeshian et al (1703.04709

Damage evolution in wood – pattern recognition based on acoustic emission (AE) frequency spectra

Tensile tests of miniature spruce wood specimens have been performed to investigate the damage evolution in wood at the microscopic scale. For this purpose, the samples were stepwise tensile loaded in the longitudinal (L) and radial (R) directions and the damage evolution was monitored in real-time by acoustic emission (AE) and synchrotron radiation micro-computed tomography (SRμCT). This combination is of outstanding benefit as SRμCT monitoring provides an insight on the crack evolution and the final fracture at microscopic scale, whereas AE permits the detection of the associated accumulation and interaction of single damage events on all length scales with high time resolution. A significant drawback of the AE testing of wood has been overcome by means of calibrating the AE amplitudes with the underlying crack length development. Thus, a setup-dependent and wood species-dependent calibration value was estimated, which associates 1 μm