Shared Reference Frame Research Articles

How to use polarity thinkingTM to manage tensions between accountability and learner agency when using a multipurpose portfolio?

ABSTRACT Portfolios are often implemented to target multiple purposes, e.g. assessment, accountability and/or self-regulated learning. However, in educational practice, it appears to be difficult to combine different purposes in one portfolio, as interdependencies between the purposes can cause tensions. This paper explored directions to manage tensions that are inextricably linked to multipurpose portfolio use. We used a systems thinking methodology, that was based on the polarity thinkingTM framework. This framework provides a step-by-step approach to chart a polarity map® that can help to balance the tensions present in specific settings. We followed the steps of the framework to chart a polarity map for multipurpose portfolio use. Based on literature and our prior research, we selected one overarching polarity: accountability and learner agency. This polarity seems responsible for multiple tensions related to multipurpose portfolio use. We formulated values (potential benefits) and fears (tensions that can arise) of the two poles of this polarity. Then, we organised a session with stakeholders who work with the portfolio of the Dutch General Practice speciality programme. Together we formulated action steps and early warnings that can help to balance accountability and learner agency during multipurpose portfolio use. In addition to previous recommendations concerning portfolio use, we advocate that it is important to create a shared frame of reference between all involved with the multipurpose portfolio. During this process, the acknowledgement and discussion of tensions related to multipurpose portfolio use are vital.

Entropy, Deterministic Chaos, and New Forms of Intelligibility: A Shared Frame of Reference for Physics and Psychology

Prigogine’s theory of dissipative structures provides a general account of entropy-driven self-organized transitions through hierarchies of structures separated by discontinuities. The theory encompasses a wide range of evolving systems throughout nature and culture. Possibilities for operationalizing a new collective rationality spanning physics and psychology emerge from Prigogine’s emphases on two distinct senses of probability, on the concept of the sufficient statistic, and on the role and limitations of the Poisson distribution in formulating a “nonlinear master equation.” Unnoted by Prigogine are correspondences of all three of these issues in the mathematical foundations of statistics and measurement established in the works of Ronald Fisher and his student, Georg Rasch. The three areas of correspondence inform models enabling specifically metrological approaches to quality-assured quantification across the sciences. Prigogine’s sense of “deterministic chaos” is re-expressed in measurement terms as stochastic invariance and the need for “a supplementary parameter” augmenting the Poisson distribution is related to a rating scale model of measurement. In light of these connections, this paper proposes that what Prigogine anticipates as a “new intelligibility” and a new science of “collective rationality” could be pragmatically operationalized in a new metrological infrastructure made coherent by the generality of entropy-driven nonequilibrium processes.

Average correlation as an indicator for inseparability

Inseparability of quantum states is one of the most crucial aspects of quantum physics, as it often provides the key ingredient for obtaining a quantum advantage. Quantifying inseparability is thus an important objective to better understand quantum physics and to improve quantum applications. So far, many measures for inseparability exist, however, most of them are based on abstract mathematical procedures and are not defined operationally which can easily be realized in an experiment. Recently we introduced average correlation [Tschaffon , ] as a reference frame independent indicator for nonclassicality in the Bell sense based on randomized measurements. It is defined as the average absolute value of the two-qubit correlation function and allows one to formulate a necessary and sufficient condition for the ability to violate the CHSH inequality. Experimentally it can be realized by randomized measurements which can approximate its value arbitrarily closely. This makes it independent of a shared reference frame between the two measuring parties, which can be useful in scenarios where it is impossible to find one. In this second article, we show that average correlation also serves as an indicator for inseparability by deriving a necessary and sufficient condition. From there, we prove the remaining open conjectures of the first article. Due to the operational definition of average correlation, it offers a first step toward finding a new operationally defined inseparability measure. Published by the American Physical Society 2024

Agent-Object Relationships in Level-2 Visual Perspective Taking: An Eye-Tracking Study.

Visual perspective taking (VPT) generates a shared frame of reference for understanding how the world appears to others. Whilst greater cognitive and neurophysiological demands are associated with increasing angular distance between the self and other is well documented, accompanying attentional characteristics are not currently understood. Furthermore, although age and group status have been shown to impact task performance, other important cues, such as the relationship between agents and objects, have not been manipulated. Therefore, 35 university students participated in an eye-tracking experiment where they completed a VPT task with agents positioned at a low or high angular disparity (45° or 135° respectively). The congruence between the age of the agent (child vs adult) and the object they are attending to (e.g., teddy-bear vs kettle) was also manipulated. Participants were required to respond to the direction of the object from the agent's position. The findings reveal more fixations and increased dwell-times on agents compared to objects, but this was moderated by the age of the task agent. Results also showed more attentional transitions between agents and objects at higher angular disparities. These results converge with behavioural and neurophysiological descriptions of task performance in previous studies. Furthermore, the congruency of the relationship between agents and objects also impacted attention shifting and response times, highlighting the importance of understanding how social cues and contexts can modulate VPT processes in everyday contexts and social interaction.

Complete Characterization of Quantum Correlations by Randomized Measurements.

The fact that quantum mechanics predicts stronger correlations than classical physics is an essential cornerstone of quantum information processing. Indeed, these quantum correlations are a valuable resource for various tasks, such as quantum key distribution or quantum teleportation, but characterizing these correlations in an experimental setting is a formidable task, especially in scenarios where no shared reference frames are available. By definition, quantum correlations are reference-frame independent, i.e., invariant under local transformations; this physically motivated invariance implies, however, a dedicated mathematical structure and, therefore, constitutes a roadblock for an efficient analysis of these correlations in experiments. Here we provide a method to directly measure any locally invariant property of quantum states using locally randomized measurements, and we present a detailed toolbox to analyze these correlations for two quantum bits. We implement these methods experimentally using pairs of entangled photons, characterizing their usefulness for quantum teleportation and their potential to display quantum nonlocality in its simplest form. Our results can be applied to various quantum computing platforms, allowing simple analysis of correlations between arbitrary distant qubits in the architecture.

Rushing for security: a document analysis on the sources and effects of time pressure on organizational cybersecurity

PurposeA growing body of research has identified time pressure as a key driver of cybersecurity (CS) risks and vulnerabilities. To strengthen CS, organizations use CS documents (e.g. best practices, guidelines and policies) intended to strengthen CS. The purpose of this paper is to provide an overview of how specifically time pressure is addressed by CS documents.Design/methodology/approachThe authors conducted a systematic search for CS documents followed by a content analysis of the identified documents. First, the authors carried out a systematic Web search and identified 92 formal and informal CS documents (e.g. security policies, procedures, guidelines, manuals and best practices). Second, they systematically analyzed the resulting documents (n = 92), using a structured approach of data familiarization and low-/high-level coding for the identification and interpretation of themes. Based on this analysis, the authors formulated a conceptual framework that captures the sources and effects of time pressure along the themes of industry, operations and users.FindingsThe authors developed a conceptual framework that outlines the role of time pressure for the CS industry, threats and operations. This provides a shared frame of reference for researchers and practitioners to understand the antecedents and consequences of time pressure in the organizational CS context.Research limitations/implicationsWhile the analyzed documents acknowledge time pressure as an important factor for CS, the documents provide limited information on how to respond to these concerns. Future research could, hence, consult with CS experts and policymakers to inform the development of effective guidelines and policies on how to address time pressure in the identified areas. A dedicated analysis within each area will allow to investigate the corresponding aspects of time pressure in-depth along with a consideration for targeted guidelines and policies. Last, note that a differentiation between CS document types (e.g. formal vs informal and global vs regional) was beyond the scope of this paper and may be investigated by future work.Originality/valueThis study makes three main contributions to the CS literature. First, this study broadens the understanding of the role of time pressure in CS to consider the organizational perspective along the themes of industry, threats and operations. Second, this study provides the first comprehensive assessment of how organizations address time pressure through CS documents, and how this compares to existing research in academic literature. Third, by developing a conceptual framework, this study provides a shared frame of reference for researchers and practitioners to further develop CS documents that consider time pressure’s role in secure behavior.

Measurement-Device-Independent Quantum Key Distribution Based on Decoherence-Free Subspaces with Logical Bell State Analyzer.

Measurement-device-independent quantum key distribution (MDI-QKD) enables two legitimate users to generate shared information-theoretic secure keys with immunity to all detector side attacks. However, the original proposal using polarization encoding is sensitive to polarization rotations stemming from birefringence in fibers or misalignment. To overcome this problem, here we propose a robust QKD protocol without detector vulnerabilities based on decoherence-free subspaces using polarization-entangled photon pairs. A logical Bell state analyzer is designed specifically for such encoding. The protocol exploits common parametric down-conversion sources, for which we develop a MDI-decoy-state method, and requires neither complex measurements nor a shared reference frame. We have analyzed the practical security in detail and presented a numerical simulation under various parameter regimes, showing the feasibility of the logical Bell state analyzer along with the potential that double communication distance can be achieved without a shared reference frame.

Study of practical state-preparation error tolerant reference-frame-independent quantum key distribution protocol

Quantum key distribution (QKD) enables the establishment of shared keys between two distant users, Alice and Bob, based on the fundamental principles of quantum mechanics, and it has proven to possess information-theoretic security. In most of QKD systems, Alice and Bob require a shared reference frame, and real-time calibration of the reference frame increases system costs and reduces its performance. Fortunately, the reference-frame-independent QKD protocol has been proposed, overcoming reference-frame drift issues and receiving widespread attention. However, in practical QKD systems, the non-ideal characteristics of realistic devices introduce certain inconsistency between the theory and the practice. In real-world quantum key distribution systems, device imperfections can lead to security vulnerabilities, thereby reducing system security. For example, imperfections in the encoding apparatus at the source end may result in errors in the quantum states. The inherent defects in the detection part may cause after-pulse effects and dead-time effects, thus reducing the key rate. Therefore, in this work, we propose a practical state-preparation error tolerant reference-frame-independent quantum key distribution protocol by taking imperfections in both the source and the detectors into account. Moreover, a three-intensity decoy-state scheme for modeling analysis and numerical simulations is employed. In this protocol, we reduce the influence of state-preparation errors on the key rate by utilizing virtual state methods to precisely estimate the phase-error rate. Furthermore, by characterizing the effects of after-pulses and dead-time on the key rate, our protocol exhibits higher robustness and can effectively address issues related to detector imperfections. This approach can also be extended to other quantum key distribution protocols with higher security levels, such as measurement-device-independent quantum key distribution protocol and twin-field quantum key distribution, further mitigating the influence of device imperfections on practical implementation of QKD system. Therefore, our present work provide important reference value for putting the quantum key distributions into practical application.

Geopolitics, Northern Europe, and Nordic Noir: What Television Series Tell Us about World Politics

Geopolitics, Northern Europe, and Nordic Noir: What Television Series Tell Us about World Politics

Exploring typologies of consultation performance using authentic clinical experiences to support learning and assessment in postgraduate medical training

Objective: To validate and refine typologies of consultation performance from previous research to identify learning needs associated with each typology. Methods: We performed a qualitative study in a General Practice Specialty Training programme, using a two-stage design. First, we selected four exemplars from 80 videotaped consultations of 7 first-year and 6 third-year trainees that reflected the four typologies. We subsequently held individual interviews with clinical supervisors (N = 20) who observed these consultations to identify recurrent trainee behaviours. Results: The ‘doctor-patient interaction’ dimension from previous research was specified to encompass relationship-building, exploring, structuring, and shared decision-making competencies. Medical expertise was a moderating factor. The attitude and consultation behaviours included in the typologies were validated and we formulated directions for learning based on learning needs identified per typology. Conclusion: Supervisors have a shared frame of reference for the behaviours reflecting proficient consultation performance. Serving as a developmental road map, all learning needs emphasised contextual adaptation, calling for an improved balance between patient-centred relationship building and application of medical expertise. Practice implications: By providing rich and tailored feedback on consultation performance, the refined typologies – albeit subject to additional refinement in future research – may promote the monitoring of individual competence development over time.

Public Welfare Resource Mobilisation: Strategies Adopted by Christian Churches in China

Extensive studies have shown that social services of Christian churches in mainland China today are still charity-focused, and feature temporary, sporadic and unsystematic efforts. Social services of a local Christian church in city S have risen above the conventional charities through various endeavours, a success attributed mainly to a set of self-developed and effective strategies, namely centralised control to boost organisational efficacy, collective identity cultivation to build a shared frame of reference and capitalising on favourable political circumstances to tap external resources. Specifically, improved organisational efficacy offers stable institutional support; a shared frame of reference ignites internal driving power; and external support catalyses greater public engagement. A closer examination of these strategies reveals the modes of church–government interactions that vary from one context to another. On the one hand, China's religious affairs authorities remain sceptical towards churches, while local governments, on the other hand, have taken initiatives to explore collaborations with churches to address their needs for effective governance. Manoeuvring between religious affairs authorities and local governments, local Christian churches have managed to blaze a trail of social engagement to demonstrate their social and public orientations without going against the national discourse.

Encoding the information in relative parameters

We investigate the problem of communicating three parameters in the absence of shared reference frame. We explore two methods in which the relative angles of spins are used to encode the parameters. In the first method we use three spins that carry the information in their relative angles while in the second method we use three disjoint spin-pairs and the information is sent through the relative angles of each individual pair. We show that in the first method, the information conveyed by each qubit is more than the second one, and that is while it requires fewer particles.

A Moment for Random Measurements

Quantum entanglement is one of the core features of quantum theory. While it is typically revealed by measurements along carefully chosen directions, here we review different methods based on so-called random or randomized measurements. Although this approach might seem inefficient at first, sampling correlations in various random directions is a powerful tool to study properties which are invariant under local-unitary transformations. Based on random measurements, entanglement can be detected and characterized without a shared reference frame between the observers or even if local reference frames cannot be defined. This overview article discusses different methods using random measurements to detect genuine multipartite entanglement and to distinguish SLOCC classes. Furthermore, it reviews how measurement directions can efficiently be obtained based on spherical designs.

Experimental Demonstration of Robust Quantum Steering

We analyze and experimentally demonstrate quantum steering using criteria based on generalized entropies and criteria with minimal assumptions based on the so-called dimension-bounded steering. Further, we investigate and compare their robustness against experimental imperfections such as misalignment in the shared measurement reference frame. While entropy based criteria are robust against imperfections in state preparation, we demonstrate an advantage in dimension-bounded steering in the presence of measurement imprecision. As steering with such minimal assumptions is easier to reach than fully nonlocal correlations, and as our setting requires very little trust in the measurement devices, the results provide a candidate for the costly Bell tests while remaining highly device independent.

Quantum key distribution with no shared reference frame

Any quantum communication task requires a common reference frame (i.e. phase, coordinate system). In particular, Quantum Key Distribution requires different bases for preparation and measurements of states which are obviously based on the existence of a common frame of reference. Here we show how QKD can be achieved in the absence of any common frame of reference. We study the coordinate reference frame, where the two parties do not even share a single direction, but the method can be generalized to other general frames of reference, pertaining to other groups of transformations.

Facilitators and barriers to effective information sharing during international disaster response.

Effective information sharing is essential for the successful management of disasters. But as 30 years' worth of UK public inquiries repeatedly highlight, differences in terminology and goals across agencies can make this difficult to achieve. The growing scale and intensity of disasters raises additional challenges, with emergency responders being required to work across regions and even countries. The following study focuses on identifying facilitators and barriers to information sharing in dynamic contexts, where interdisciplinary teams from across geographic regions form ad hoc to rapidly address challenges. This case study draws on 257 naturalistic observations made by subject-matter experts during the largest disaster management exercise to take place in Europe to date. The 4-day exercise, funded by the European Commission, involved over 5,000 emergency responders from the UK, Cyprus, Hungary, and Italy, providing a unique opportunity to examine information sharing practices across international boundaries. Results of a mixed-method analysis highlight that barriers within and between countries are particularly prevalent during periods of greater uncertainty. These barriers include language and technological difficulties, differences in roles and responsibilities, and failure to co-locate and coordinate activities. Developing shared frames of reference, including adopting common structures for presenting information and understanding roles and responsibilities, facilitates information sharing, potentially reducing cognitive load. Implications for developing evidence-based approaches to disaster response are discussed.

Experimental realization of a reference-frame-independent decoy BB84 quantum key distribution based on Sagnac interferometer.

Quantum key distribution (QKD) can generate secure key bits between remote users employing the features of quantum physics. However, a shared reference frame is necessary for QKD systems in most scenarios. A reference-frame-independent (RFI) scheme can tolerate the reference frame drifting between legitimate remote users, which is significant in the operation of relative moving terminals such as satellites and aircraft. We design and experimentally demonstrate an RFI-BB84-QKD system by joint encoding with the polarization and orbital angular momentum states of the photons. We use self-compensating fiber Sagnac interferometers to perform high-speed polarization modulation, and q-plates to passively manipulate the rotation-invariant photon states, which makes the system feasible for high-speed operation using off-the-shelf components.

Power of a shared singlet state in comparison to a shared reference frame

We show that a Shared Singlet State (SSS) can supersede a Shared Reference Frame (SRF) in certain quantum communication tasks, i.e. tasks in which two remote players are required to estimate certain parameters of a two particle state sent to them. This shows that task specific value of resources maybe some what different from their common values based on their exchange possibilities.

Communicating without shared reference frames

We generalize a quantum communication protocol introduced by Bartlett et al. [New J. Phys. 11, 063013 (2009)], in which two parties communicating do not share a classical reference frame, to the case where changes of their reference frames form a one-dimensional noncompact Lie group. Alice sends to Bob the state ${\ensuremath{\rho}}_{R}\ensuremath{\bigotimes}{\ensuremath{\rho}}_{S}$, where ${\ensuremath{\rho}}_{S}$ is the state of the system Alice wishes to communicate and ${\ensuremath{\rho}}_{R}$ is the state of an ancillary system serving as a token of her reference frame. Because Bob is ignorant of the relationship between his reference frame and Alice's, he will describe the state ${\ensuremath{\rho}}_{R}\ensuremath{\bigotimes}{\ensuremath{\rho}}_{S}$ as an average over all possible reference frames. Bob measures the reference token and applies a correction to the system Alice wished to communicate conditioned on the outcome of the measurement. The recovered state ${\ensuremath{\rho}}_{S}^{\ensuremath{'}}$ is decohered with respect to ${\ensuremath{\rho}}_{S}$, the amount of decoherence depending on the properties of the reference token ${\ensuremath{\rho}}_{R}$. We present an example of this protocol when Alice and Bob do not share a reference frame associated with the one-dimensional translation group and use the fidelity between ${\ensuremath{\rho}}_{S}$ and ${\ensuremath{\rho}}_{S}^{\ensuremath{'}}$ to quantify the success of the recovery operation.

Entanglement-assisted communication in the absence of shared reference frame

Alice wants to convey the value of a parameter to Bob with whom she does not share a reference frame. What physical object can she use for this task? Shall she encode this value into the angle between two physical vectors such as the angle between two spins? Can she benefit from using entanglement? We approach these questions here and show that an entangled state of two qubits has three parameters that are invariant under changes of the reference frame. We also calculate the average information gain, when each one of these parameters is used for communication. We compare our result with the special case of separable states and find that entanglement enhances the information gain.