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In this paper, we extend the Unruh-DeWitt (UDW) model to include a relativistic quantized center of mass (c.m.) for the detector, which traditionally has a classical c.m. and follows a classical trajectory. We develop a relativistic model of an inertial detector following two different approaches, starting from either a first- or second-quantized treatment, which enables us to compare the fundamental differences between the two schemes. In particular, we find that the notion of localization is different between the two models, and leads to distinct predictions, which we study by comparing the spontaneous emission rates for the UDW detector interacting with a massless scalar field. Furthermore, we consider the UDW system in both a vacuum and medium, and compare our results to existing models describing a classical or quantized c.m. at low energies. We find that the predictions of each model, including the two relativistic cases, can in principle be empirically distinguished, and our results can be further extended to find optimal detector states and processes to perform such experiments. This would clarify both the role of a quantized c.m. for interactions with an external field, and the differing localizations between the first- and second-quantized treatments., Comment: 18 pages, 5 figures (v2: extended discussion, additional references and other minor corrections)

Within any anticipated unifying theory of quantum gravity, it should be meaningful to combine the fundamental notions of quantum superposition and spacetime to obtain so-called "spacetime superpositions": that is, quantum superpositions of different spacetimes not related by a global coordinate transformation. Here we consider the quantum-gravitational effects produced by superpositions of periodically identified Minkowski spacetime (i.e.\ Minkowski spacetime with a periodic boundary condition) with different characteristic lengths. By coupling relativistic quantum matter to fields on such a spacetime background (which we model using the Unruh-deWitt particle detector model), we are able to show how one can in-principle "measure" the field-theoretic effects produced by such a spacetime. We show that the detector's response exhibits discontinuous resonances at rational ratios of the superposed periodic length scale., 7+4 pages, 3 figures

A simple but powerful particle detector model consists of a two-level system coupled to a field, where the detected particles are the field excitations. This is known as the Unruh-DeWitt detector. Research using this model has often focused on either a completely classical description of the external degrees of freedom of the detector, or a full field-theoretic treatment, where the detector itself is described as a field. Recently there has been much interest in quantum aspects of the detector's center of mass -- either described as moving in superposition along semiclassical trajectories, or dynamically evolving under a non-relativistic Hamiltonian. However, the processes of interest -- the absorption or emission of field particles -- necessarily change the detector's rest mass by the amount of energy of the absorbed or emitted field quanta. Neither of the above models can capture such effects. Here we incorporate the quantization of the detector's mass-energy into the Unruh-DeWitt model. We show that internal energy changes due to emission or absorption are relevant even in the lowest energy limit. Specifically, corrections to transition rates due to the detector's mass changing cannot be ignored unless the entire center of mass dynamics is also ignored. Our results imply that one cannot have a consistent model of the Unruh-DeWitt detector as a massive particle without including the mass-energy equivalence., 10 pages, includes 3 figures

In the absence of a fully-fledged theory of quantum gravity, we propose a "bottom-up" framework for exploring quantum-gravitational physics by pairing two of the most fundamental concepts of quantum theory and general relativity, namely quantum superposition and spacetime. We show how to describe such "spacetime superpositions" and explore effects they induce upon quantum matter. Our approach capitalizes on standard tools of quantum field theory in curved space, and allows us to calculate physical observables like transition probabilities for a particle detector residing in curvature-superposed de Sitter spacetime, or outside a mass-superposed black hole. Crucially, such scenarios represent genuine quantum superpositions of spacetimes, in contrast with superpositions of metrics which only differ by a coordinate transformation and thus are not different according to general relativity., Comment: 12 pages, Honourable Mention in the Gravity Research Foundation 2022 Awards for Essays on Gravitation

The paper presents the results of the academic museum Project called Anthropological reinterpretation of the Siberian collections from the Ethnographic Museum in Cracow that came from Polish 19th-century explorers of Siberia financed by the National Programme for the Development of Humanities (2016–2019). Four major topics of investigation among the collections’ source communities have been presented: Benedykt Dybowski’s collection from Kamchatka, Konstanty Podhorski’s collection from Chukotka, Nenets’ clothing donated by Izydor Sobański, and two cult figurines which reached the Cracow Museum from Jan Żurakowski. The presentation reveals the assumptions of the in-field museology: the method combining the anthropological perspective with museology elements. Furthermore, the digital repository www.etnomuzeum.eu/syberia is discussed; it is the one that makes the collections and research results available online. The paper may prove of interest to professionals curating collections, culture researchers, historians, cultural anthropologists, art historian, conservation services, museology theoreticians.

Gravitationally bound neutrons have become an important tool in the experimental searches for new physics, such as modifications to Newton's force or candidates for dark matter particles. Here we include the relativistic effects of mass-energy equivalence into the model of gravitationally bound neutrons. Specifically, we investigate a correction in a gravitationally bound neutron's Hamiltonian due to the presence of an external magnetic field. We show that the neutron's additional weight due to mass-energy equivalence will cause a small shift in the neutron's eigenenergies and eigenstates, and examine how this relativistic correction would affect experiments with trapped neutrons. We further consider the ultimate precision in estimating the relativistic correction to the precession frequency and find that, at short times, a joint measurement of both the spin and motional degrees of freedom provides a metrological enhancement as compared to a measurement of the spin alone.

The hyperbaric oxygen therapy (HBOT) involves the use of 100% pure oxygen in conditions of increased pressure, exceeding atmospheric pressure. This allows the supply of several times more oxygen to internal organs and blood serum than when using standard pressure. HBOT has proven to support the treatment of autoimmune skin diseases, complications of metabolic diseases and burns, as confirmed by clinical studies. In addition, this therapy can also be used to improve the physiological condition of the skin after cosmetology procedures. The aim of this work is to review information on the therapeutic effects of hyperbaric oxygen therapy in the treatment of skin diseases, especially atopic dermatitis, psoriasis, diabetic foot, second degree burns and complications after cosmetic procedures. The review was based on the works published in the last twenty years (1999-2019), available in the following databases: PubMed, GoogleSchoolar, PEDro. The use of HBOT is becoming more common in the treatment of skin complications of diabetes, as well as burn wounds. It is estimated that HBOT reduces the risk of foot ulcers and amputation in diabetic foot syndrome. In addition, HBOT promotes faster healing of burn wounds, also with the use of allogenic skin grafts. By increasing the level of reactive oxygen species (ROS), hyperbaric oxygen therapy significantly supports the treatment of psoriasis and atopic dermatitis. Despite this, the exact mechanisms of hyperbaric oxygen are still poorly understood, and the use of HBOT in the treatment of skin diseases has not yet been included in treatment protocols.

The term ‘locomotor adaptations’ (LMA) indicates the alteration in motor commands that is automatically or volitionally generated in response to a perturbation continuously altering the task demands of locomotion. LMAs have been widely studied, using a variety of experimental paradigms and analysis techniques. The perturbation can be expected or unexpected and constituted by a change in the movement environment, by forces actively pushing the person’s body segments, by a modification in the sensory feedback associated with the task or by explicit task instructions. The study of LMAs has been key in widening our understanding of the principles regulating bipedal locomotion, from the overall strategies driving the short-term adjustments of motor commands, down to the different neural circuits involved in the different aspects of locomotion. In this paper we will provide an in-depth review of the research field of LMAs. We will start with an analysis of the principles driving the evolution of bipedal locomotion in humans. Then we will review the different experimental paradigms that have been used to trigger LMAs. We will analyze the evidence on the neurophysiological correlates of adaptation and the behavioral reasons behind it. We will then discuss the characteristics of LMA such as transfer, generalization, and savings. This will be followed by a critical analysis of how different studies point to different task-goal related drivers of adaptation. Finally, we will conclude with a perspective on the research field of LMAs and on its ramifications in neuroscience and rehabilitation.

Introduction. Professional image of the nurse in the opinion of the patient community is conditioned by many variables, including professional attire. A worthy representation of the nurse profession is the responsibility of all those who care for the patient. Aim. Determining the impact of dress code on shaping the professional image of nurses in the opinion of patients. Material and methods. Non-systematic review method of the literature available. The data was obtained by searching online databases, such as: Google Scholar, PubMed, CINAHL Complete as well as electronic resources of nursing magazines. Results. In the perception of hospitalized patients, the nursing dress code affects the level of trust in those who care for patients, it also constitutes an important element in assessing their professionalism, knowledge or confidence when performing specific medical interventions. Adapted to the needs, a suitably selected style of professional attire of a nurse employed in a given health care facility enables her proper identification of them against the background of other members of the therapeutic team or administrative employees. In addition, the comfort of nurses is a significant factor for patients in dress code strategy planning; it often determines professionalism and quality of services provided. Conclusions. There is a relationship between the external appearance of nurses and their professional image and the patients’ perception of their professional skills as well as the level of their professionalism. Dress code in a health care facility may constitute a significant element of image policy for both a health care facility itself and a group of nurses.

We consider an entanglement harvesting protocol between two Unruh-deWitt detectors in quantum superpositions of static trajectories in the static de Sitter and thermal Minkowski spacetimes. We demonstrate for the first time that the spatial superposition of each detector's path allows entanglement to be harvested from the quantum field in regimes where it would be otherwise impossible for detectors on classical trajectories. Surprisingly, for detectors on sufficiently delocalised trajectories in a thermal bath, the amount of harvested entanglement grows with the temperature of the field, violating a no-go theorem derived by Simidzija et. al. (Phys. Rev. D 98, 085007). We also discover interesting effects for mutual information harvesting, which depends sensitively on the nonlocal correlations between the superposed trajectories between the paths of the respective detectors., 17 pages, 23 figures. Accepted in PRD

We present new theoretical models for quantum optical mode-selective filters and mirrors using continuous-variable teleportation. We call these devices telefilters and telemirrors respectively. Both devices act as the identity channel on a mode of interest from an input multi-mode field while filtering or reflecting all the orthogonal modes. We utilise these models to analyse a causality problem in relativistic quantum optics, specifically the apparently acausal transmission and propagation of temporally delocalised wavepackets through mode-selective mirrors. Firstly, we show how telemirrors - and thus mode-selective operations generally - enact a fundamental time-delay on such wavepackets, which is necessary in order to prevent violations of causality. In an attempt to circumvent this delay, we next consider teleporting the independent temporal components of the input field separately and continuously, that is, performing operations on-the-run. In this scenario, the telemirror transmits the mode of interest as well as orthogonal modes which carry with them uncorrelated noise. In this scenario, the device may be considered mode-discriminating but not mode-selective., Comment: 14+12 pages, 11 figures

Tekst poświęcony jest przedstawieniu web scrapingu oraz możliwości współpracy z pracownią web scrapingu w Instytucie Studiów Informacyjnych Uniwersytetu Jagiellońskiego w ramach projektów badawczych, wdrożeniowych i użytkowych. Web scraping to technika pozyskiwania danych z Internetu. Omówiono narzędzia, etapy oraz korzyści i możliwe obszary zastosowania web scrapingu w analityce danych i badaniach mixedmethod research. Porównano web scraping z pozyskiwaniem danych za pomocą API oraz wskazano uwarunkowania prawne i etyczne web scrapingu. Na końcu przedstawiono projekt z zakresu web scrapingu, który realizowany jest jako minigrant w POB DigiWorld, w tym cele projektu, sposób nawiązywania współpracy z pracownią oraz stosowaną procedurę web scrapingu z wykorzystaniem środowiska Google Colab oraz Pythona i jego wybranych bibliotek. The article concerns web scraping and a possibility of cooperation with a web scraping lab at the Institute of Information Studies of the Jagiellonian University as a part of research, development and implementation projects. Web scraping is a technique for extracting data from the Internet. Steps, tools, advantages and research fields regarding the usage of web scraping were listed. In addition, web scraping was compared to an API extraction. Legal and ethical issues of web scraping were pointed out, too. Finally, a web scraping project founded as a DigiWorld research mini-grant was described, including its aims, a way of cooperation with the lab and the developed procedure of web scraping using Google Colab, Python and selected Python libraries.

We present a new operational framework for studying ``superpositions of spacetimes'', which are of fundamental interest in the development of a theory of quantum gravity. Our approach capitalizes on nonlocal correlations in curved spacetime quantum field theory, allowing us to formulate a metric for spacetime superpositions as well as characterizing the coupling of particle detectors to a quantum field. We apply our approach to analyze the dynamics of a detector (using the Unruh-deWitt model) in a spacetime generated by a BTZ black hole in a superposition of masses. We find that the detector exhibits signatures of quantum-gravitational effects corroborating and extending Bekenstein's seminal conjecture concerning the quantized mass spectrum of black holes in quantum gravity. Crucially, this result follows directly from the approach, without any additional assumptions about the black hole mass properties., Comment: Close to published version. Supplemental materials found on publisher's website

Przedmiotem tekstu jest zarządzanie informacją w procesie adopcji psów. Przyjęto podejście kognitywne, zakładając, że opis psa sporządzony przez organizację pośredniczącą w adopcji prowadzi do wytworzenia w umyśle odbiorcy - potencjalnego adoptującego - określonego obrazu zwierzęcia. Trafność tego mentalnego obrazu (reprezentacji) zależy od trafności samego opisu oraz kompetencji odbiorcy i wpływa na skuteczną adopcję. Przedstawiono studium przypadku bezdomnego psa o imieniu Biszkopt, który przebywał pod opieką dwóch organizacji: Org1 i Org2. Każda z nich przygotowała własny opis Biszkopta. Pies znalazł nowy dom niedługo po przeniesieniu do Org 2 (w kwietniu 2020 roku), ale uciekł i zginął nazajutrz po adopcji. Podstawowym celem badania było wskazanie różnic i podobieństw w opisach Biszkopta zredagowanych przez Org1 i Org2. Dodatkowym celem była analiza reakcji i komentarzy zamieszczanych w mediach społecznościowych pod wpisami Org1 i Org2, w których informowano o śmierci Biszkopta. Materiał empiryczny do studium przypadku składa się z tekstów i przekazów wizualnych, pobranych ręcznie ze stron internetowych oraz publicznych profili Org1 i Org2 na Facebooku. Analizie porównawczej poddano osiem tekstów. Przeanalizowano także 899 reakcji oraz 241 komentarzy. W badaniu uwzględniono wyłącznie warstwę pisemną opisów, z pominięciem zdjęć i multimediów. Analiza opisów wykazała znaczące różnice w sposobach reprezentacji Biszkopta. Org1 przedstawiała go jako lękliwego, tymczasem zdaniem Org2 był to pies spokojny i pogodny, który cierpiał jedynie na lęk separacyjny, ale potrafił spacerować na smyczy i reagował na przywoływanie. Artykuł jest przyczynkiem do dalszych badań nad związkiem między sposobami zarządzania informacją w publicznych opisach przedadopcyjnych zwierząt a powodzeniem adopcji. The research concerns information management in a dog adoption process. A cognitive approach was used, in which a dog's description, prepared by a pet adoption organization, leads to a formation of a dog's image in the mind of a reader - a prospective caretaker. The accuracy of this mental image (representation) depends on the accuracy of the description, as well as on knowledge and skills of the reader. All this impacts a successful adoption. The research is based on the case of a rescue dog named Biszkopt, which was taken care of by two animal organizations - Org1 and Org2. Separate descriptions of Biszkopt were published online by both Org1 and Org2. Following a transfer to the Org2, Biszkopt got adopted almost immediately, in April 2020. The next day after the adoption Biszkopt run away and died in a car accident. The aim was to identify the differences and the similarities between descriptions of Biszkopt edited by Org1 and Org2. The additional aim was to analyze social media reactions and comments to information on Biszkopt's death. In the framework of this case study, empirical evidence (texts and emoticons, excluding photos and multimedia) was manually extracted from websites and Facebook public profiles run by Org1 and Org2. A comparative analysis, applied to eight texts, 899 Facebook reactions and 241 comments, showed that Biszkopt's images shaped respectively by both organizations were different. According to Org1, the dog was fearful, meanwhile Org2 depicted him as a calm and positive, suffering of separation anxiety, but trained in a leash walking and coming back on call. The paper contributes to further research on the link between information management in publicly available pre-adoption dogs' descriptions and adoption success.

Quantum gravity is expected to contain descriptions of semiclassical spacetime geometries in quantum superpositions. To date, no framework for modelling such superpositions has been devised. Here, we provide a new phenomenological description for the response of quantum probes (i.e. Unruh-deWitt detectors) on a spacetime manifold in quantum superposition. By introducing an additional control degree of freedom, one can assign a Hilbert space to the spacetime, allowing it to exist in a superposition of spatial or curvature states. Applying this approach to static de Sitter space, we discover scenarios in which the effects produced by the quantum spacetime are operationally indistinguishable from those induced by superpositions of Rindler trajectories in Minkowski spacetime. The distinguishability of such quantum spacetimes from superpositions of trajectories in flat space reduces to the equivalence or non-equivalence of the field correlations between the superposed amplitudes., Comment: 15+3 pages, 10 figures. Accepted in CQG

Particle detector models such as the Unruh-deWitt detector are widely used in relativistic quantum information and field theory to probe the global features of spacetime and quantum fields. These detectors are typically modelled as coupling locally to the field along a classical worldline. In this paper, we utilize a recent framework which enables us to prepare the detector in a quantum-controlled superposition of trajectories, and study its response to the field in finite-temperature Minkowski spacetime and an expanding de Sitter universe. Unlike a detector on a classical path which cannot distinguish these spacetimes, the superposed detector can do so by acquiring nonlocal information about the geometric and causal structure of its environment, demonstrating its capability as a probe of these global properties., 8 pages, 6 figures

Observers following special classes of finite-lifetime trajectories have been shown to experience an effective temperature, a generalisation of the Unruh temperature for uniformly accelerated observers. We consider a mirror following such a trajectory - and is hence localised to a strictly bounded causal diamond - that perfectly reflects incoming field modes. We find that inertial observers in the Minkowski vacuum detect particles along the half null-rays at the beginning and end of the mirror's lifetime. These particle distributions exhibit multi-partite entanglement, which reveals novel structure within the vacuum correlations. The interaction is modelled using a non-perturbative circuit model and does not suffer from energy divergences., 8 pages, 6 figures, 2 pages of appendices. Additional comments regarding interaction model and entanglement generation

Unruh-deWitt detectors have been utilised widely as probes for quantum particles, entanglement and spacetime curvature. Here, we extend the standard treatment of an Unruh-deWitt detector interacting with a massless, scalar field to include the detector travelling in a quantum superposition of classical trajectories. We derive perturbative expressions for the final state of the detector, and show that it depends on field correlation functions evaluated locally along the individual trajectories, as well as non-locally between the superposed trajectories. By applying our general approach to a detector travelling in a superposition of two uniformly accelerated trajectories, including those with equal and differing proper accelerations, we discover novel interference effects in the emission and absorption spectra. These effects can be traced to causal relations between the superposed trajectories. Finally, we show that in general, such a detector does not thermalise even if the superposed paths would individually yield the same thermal state., Latest version has updated figures and notation

Quantum interference of "clocks", namely of particles with time-evolving internal degrees of freedom (DOFs), is a promising avenue to test genuine general relativistic effects in quantum systems. The clock acquires which path information while experiencing different proper times on traversing the arms of the interferometer, leading to a drop in its path visibility. We consider scenarios where the clock is subject to environmental noise as it transits through the interferometer. In particular, we develop a generalized formulation of interferometric visibility affected by noise on the clock. We find that, for small noise and small proper time difference between the arms, the noise further reduces the visibility, while in more general situations it can either increase or reduce the visibility. As an example, we investigate the effect of a thermal environment constituted by a single field mode and show that the visibility drops further as the temperature is increased. Additionally, by considering noise models based on standard quantum channels, we show that interferometric visibility can increase or decrease depending on the type of noise and also the time scale and transition probabilities. The quantification of the effect of noise on the visibility -- particularly in the case of a thermal environment paves the way for a better estimate on the expected outcome in an actual experiment., 21 pages, 11 figures, Accepted in Quantum

Quantum field theory is completely characterized by the field correlations between spacetime points. In turn, some of these can be accessed by locally coupling to the field simple quantum systems, also known as particle detectors. In this letter we consider what happens when a quantum-controlled superposition of detectors at different space-time points is used to probe the correlations of the field. We show that, due to quantum interference effects, two detectors can gain information on field correlations that would not be accessible, otherwise. This has relevant consequences for information theoretic quantities, like entanglement and mutual information harvested from the field. In particular, the quantum control allows for extraction of entanglement in scenarios where this is, otherwise, provably impossible.

The research aim is to investigate the relationship between skills required for a business analyst’s (BA) job and learning outcomes from selected Library and Information Science (LIS) degrees in Poland. Two hypotheses are stated: 1. Employers in Poland look for their future BAs among graduates with different degrees; 2. LIS-related degrees provide the core competences required for a BA job in Poland. An analysis of job offers for BAs in Poland was made, along with a comparative analysis of BA skills from the Standard Classification of Occupations, version 3 of the Guide to Business Analysis Body of Knowledge (BABOK 3), job offers and learning outcomes from Polish LIS-related degree courses. The most common requirements posted in job offers are language skills, knowledge of IT tools, communication, presentation and mediation skills, personality traits and analytical skills. Distinctive BA features such as understanding the nature of business analysis, requirements engineering, using notations and process frameworks, systems modelling and programming were found only in job offers and BABOK 3. Recommendations are made for LIS-related degree courses on how to deal with the mismatch between the skills required in the job market and those received through formal education.

The adaptation to visuomotor rotations is one of the most studied paradigms of motor learning. Previous literature has presented evidence of a dependency between the process of adaptation to visuomotor rotations and the constrains dictated by the workspace of the biological actuators, the muscles, and their co-activation strategies, modeled using muscle synergies analysis. To better understand this relationship, we asked a sample of healthy individuals (N = 7) to perform two experiments aiming at characterizing the adaptation to visuomotor rotations in terms of rotations of the activation space of the muscle synergies during isometric reaching tasks. In both experiments, subjects were asked to adapt to visual rotations altering the position mapping between the force exerted on a fixed manipulandum and the movement of a cursor on a screen. In the first experiment subjects adapted to three different visuomotor rotation angles (30°, 40°, and 50° clockwise) applied to the whole experimental workspace. In the second experiment subjects adapted to a single visuomotor rotation angle (45° clockwise) applied to eight different sub-spaces of the whole workspace, while also performing movements in the rest of the unperturbed workspace. The results from the first experiment confirmed the hypothesis that visuomotor rotations induce rotations in the synergies activation workspace that are proportional to the visuomotor rotation angle. The results from the second experiment showed that rotations affecting limited sub-spaces of the whole workspace are adapted for by rotating only the synergies involved in the movement, with an angle proportional to the distance between the preferred angle of the synergy and the sub-space covered by the rotation. Moreover, we show that the activation of a synergy is only rotated when the sub-space covered by the visual perturbation is applied at the boundaries of the workspace of the synergy. We found these results to be consistent across subjects, synergies and sub-spaces. Moreover, we found a correlation between synergies and muscle rotations further confirming that the adaptation process can be well described, at the neuromuscular level, using the muscle synergies model. These results provide information on how visuomotor rotations can be used to induce a desired neuromuscular response. Science Foundation Ireland University College Dublin Insight Research Centre

The validity of just a few physical conditions comprising the Einstein equivalence principle (EEP) suffices to ensure that gravity can be understood as spacetime geometry. The EEP is therefore subject to ongoing experimental verification, with present-day tests reaching the regime in which quantum mechanics becomes relevant. Here we show that the classical expression of the EEP does not apply in such a regime. The EEP requires equivalence between the rest mass-energy of a system, the mass-energy that constitutes its inertia, and the mass-energy that constitutes its weight. In quantum mechanics, the energy contributing to the mass is given by a Hamiltonian operator of the internal degrees of freedom. Therefore, we introduce a quantum expression of the EEP—equivalence between the rest, inertial and gravitational internal energy operators. Validity of the classical EEP does not imply the validity of its quantum formulation, which thus requires independent experimental verification. We propose new tests as well as re-analysing existing experiments, and we discuss to what extent they allow quantum aspects of the EEP to be tested.

Introduction. On 20-26 October 2017, nursing students representing the Medical University of Lublin had a chance to take part in the fifth European Meeting and Conference of Nursing Students in Magdeburg. Aim. This manuscript is aimed at analyzing the nurses' education system in Germany and presenting the activities of the German Nurses Association (DBfK). Summary. There are several paths of education for nurses in Germany, academic education is one of the options. Nurses associated in the German Nursing Association (DBfK) strive to increase the interest of nurses in tertiary education, as well as make efforts to create a nursing self-government.

Time has a fundamentally different character in quantum mechanics and in general relativity. In quantum theory events unfold in a fixed time order while in general relativity temporal order is influenced by the distribution of matter. When the distribution of matter requires a quantum description, temporal order is expected to become non-classical -- a scenario beyond the scope of current theories. Here we provide a direct description of such a scenario. We consider a massive body in a spatial superposition and show how it leads to "entanglement" of temporal orders between time-like events in the resulting space-time. This entanglement enables accomplishing a task, violation of a Bell inequality, that is impossible under classical temporal order. Violation of the inequality means that temporal order becomes non-classical -- it cannot be described by locally defined classical variables. Our approach provides a quantitative method for investigating quantum aspects of space-time and gravity., Comment: close to published version

Entanglement is a prediction of quantum mechanics that suggests that our physical laws cannot be described by a local causal model. This has led to much debate, including Einstein's famous suggestion that quantum mechanics is an incomplete theory, and we may one day discover a deeper theory that can be described by a locally causal model. However, loophole free violations of Bell inequalities demonstrate that this is not the case. Bell's theorem is independent of quantum mechanics, and it shows that any theory attempting to supplant quantum mechanics must be somehow nonlocal. Since then, there have been many experimental violations of Bell inequalities using different physical systems, culminating in three loophole-free experiments [1–3].