Unraveling nonclassicality in the optomechanical instability

Conditional dynamics due to continuous optical measurements has successfully been applied for state reconstruction and feedback cooling in optomechanical systems. In this article, we show that the same measurement techniques can be used to unravel nonclassicality in optomechanical limit cycles. In contrast to unconditional dynamics, our approach gives rise to nonclassical limit cycles even in the sideband-unresolved regime, where the cavity decay rate exceeds the mechanical frequency. We predict a significant reduction of the mechanical amplitude fluctuations for realistic experimental parameters.Comment: 8 pages, 5 figures, equivalent to published versio

Measuring individual differences in generic beliefs in conspiracy theories across cultures: the Conspiracy Mentality Questionnaire (CMQ)

Conspiracy theories are ubiquitous when it comes to explaining political events and societal phenomena. Individuals differ not only in the degree to which they believe in specific conspiracy theories, but also in their general susceptibility to explanations based on such theories, that is, their conspiracy mentality. We present the Conspiracy Mentality Questionnaire (CMQ), an instrument designed to efficiently assess differences in the generic tendency to engage in conspiracist ideation within and across cultures. The CMQ is available in English, German, and Turkish. In four studies, we examined the CMQ’s factorial structure, reliability, measurement equivalence across cultures, and its convergent, discriminant, and predictive validity. Analyses based on a cross-cultural sample (Study 1a; N = 7,766) supported the conceptualization of conspiracy mentality as a one-dimensional construct across the three language versions of the CMQ that is stable across time (Study 1b; N = 141). Multi-group confirmatory factor analysis demonstrated cross-cultural measurement equivalence of the CMQ items. The instrument could therefore be used to examine differences in conspiracy mentality between European, North American, and Middle Eastern cultures. In Studies 2–4 (total N = 476), we report (re-)analyses of three datasets demonstrating the validity of the CMQ in student and working population samples in the UK and Germany. First, attesting to its convergent validity, the CMQ was highly correlated with another measure of generic conspiracy belief. Second, the CMQ showed patterns of meaningful associations with personality measures (e.g., Big Five dimensions, schizotypy), other generalized political attitudes (e.g., social dominance orientation and right-wing authoritarianism), and further individual differences (e.g., paranormal belief, lack of socio-political control). Finally, the CMQ predicted beliefs in specific conspiracy theories over and above other individual difference measures

Collective nostalgia: a group-level emotion that confers unique benefits on the group

This research established collective nostalgia as a group-level emotion and ascertained the benefits it confers on the group. In Study 1, participants who reflected on a nostalgic event they had experienced together with ingroup members (collective nostalgia) evaluated the ingroup more positively and reported stronger intentions to approach (and not avoid) ingroup members than those who recalled a nostalgic event they had experienced individually (personal nostalgia), those who reflected on a lucky event they had experienced together with ingroup members (collective positive), and those who did not recall an event (no recall). In Study 2, collective (vs. personal) nostalgia strengthened behavioral intentions to support the ingroup more so than did recalling an ordinary collective (vs. personal) event. Increased collective self-esteem mediated this effect. In Study 3, collective nostalgia (compared with recall of an ordinary collective event) led participants to sacrifice money in order to punish a transgression perpetrated against an ingroup member. This effect of collective nostalgia was more pronounced when social identification was high (compared with low). Finally, in Study 4, collective nostalgia converged toward the group average (i.e., was socially shared) when participants thought of themselves in terms of their group membership. The findings underscore the viability of studying nostalgia at multiple levels of analysis and highlight the significance of collective nostalgia for understanding group-level attitudes, global action tendencies, specific behavioral intentions, and behavior

Quantum Synchronization on the IBM Q System

We report the first experimental demonstration of quantum synchronization. This is achieved by performing a digital simulation of a single spin-$1$ limit-cycle oscillator on the quantum computers of the IBM Q System. Applying an external signal to the oscillator, we verify typical features of quantum synchronization and demonstrate an interference-based quantum synchronization blockade. Our results show that state-of-the-art noisy intermediate-scale quantum computers are powerful enough to implement realistic dissipative quantum systems. Finally, we discuss limitations of current quantum hardware and define requirements necessary to investigate more complex problems.Comment: equivalent to published version, 8 pages, 5 figure

Geometric Phase in Quantum Synchronization

We consider a quantum limit-cycle oscillator implemented in a spin system whose quantization axis is slowly rotated. Using a kinematic approach to define geometric phases in nonunitary evolution, we show that the quantum limit-cycle oscillator attains a geometric phase when the rotation is sufficiently slow. In the presence of an external signal, the geometric phase as a function of the signal strength and the detuning between the signal and the natural frequency of oscillation shows a structure that is strikingly similar to the Arnold tongue of synchronization. Surprisingly, this structure vanishes together with the Arnold tongue when the system is in a parameter regime of synchronization blockade. We derive an analytic expression for the geometric phase of this system, valid in the limit of slow rotation of the quantization axis and weak external signal strength, and we provide an intuitive interpretation for this surprising effect

Feminist Development Policy: What does the Population think?

The continued lack of gender equality is an urgent global challenge. Against this backdrop, the German Federal Government announced in 2021 that it would include a feminist foreign policy in its coalition agreement. The aim of this policy is to strengthen the rights, representation and resources of women and marginalised groups and to promote the recognition of diversity. However, a feminist orientation in foreign and development policy meets with diverging views in political debate and provides cause for discussion in the (social) media. But what is the attitude of the general public? Aiming to answer this question, DEval examined public opinion on feminist development policy as part of its Opinion Monitor for Development Policy 2022. This Policy Brief summarises the results of the representative survey

The Public's Expectations of Development Policy: Findings of the DEval Opinion Monitor for Development Policy 2021

This policy brief summarises the findings of the DEval Opinion Monitor for Development Policy 2021. It investigated which partner countries the general public perceives as particularly worthy of support and what socioeconomic and political characteristics of the countries are associated with this perception

Human Rights-Based Evaluation in German and International Development Cooperation: Literature Review

This literature review aims to summarise current knowledge on a human rights-based approach (HRBA) to evaluation and improve the basis for further conceptual discussions on this approach. To this end, we reviewed strategies and (publicly available) guidelines of multilateral and bilateral development actors, relevant tools for human rights in monitoring and evaluation, research articles, and evaluation reports published between 2014 and 2021

Quantum effects in amplitude death of coupled anharmonic self-oscillators

Coupling two or more self-oscillating systems may stabilize their zero-amplitude rest-state, therefore quenching their oscillation. This phenomenon is termed "amplitude death". Well-known and studied in classical self-oscillators, amplitude death was only recently investigated in quantum self-oscillators [Ishibashi et al., Phys. Rev. E 96, 052210]. Quantitative differences between the classical and quantum descriptions were found. Here, we demonstrate that for quantum self-oscillators with anharmonicity in their energy spectrum, multiple resonances in the mean phonon number can be observed. This is a result of the discrete energy spectrum of these oscillators, and is not present in the corresponding classical model. Experiments can be realized with current technology and would demonstrate these genuine quantum effects in the amplitude death phenomenon

Sustainable Consumption in the face of Global Challenges: Opportunities and Obstacles; Findings of the DEval Opinion Monitor for Development Policy 2022

Sustainable consumption contributes to sustainable global development. Due to the interdependencies between consumption behaviour in industrialised countries and people's living conditions in countries of the Global South, the issue is also highly relevant to development policy. Up to now, however, there is hardly any evidence with regard to the extent that citizens perceive their own consumption as having a global impact. The DEval Opinion Monitor for Development Policy 2022 looked into this question. This Policy Brief summarises the findings of the study