Release of virtual photon and phonon pairs from qubit-plasmon-phonon ultrastrong coupling system

The most important difference between ultrastrong and non-ultrastrong coupling regimes is that the ground state contains excitations. We consider a qubit-plasmon-phonon ultrastrong coupling (USC) system with a three-level atom coupled to the photon and phonon via its upper two energy levels and show that spontaneous emission of the atom from its intermediate to its ground state produces photon and phonon pairs. It is shown that the current system can produce a strong photon/phonon stream and the atom-phonon coupling plays the active role, which ensures the experimental detection. The emission spectrum and various high-order correlation functions confirm the generation of the pairs of photons and phonons. Our study has important implications for future research on virtual photon and phonon pairs creation in the ground state of the USC regime.Comment: 9 pages, 7 figure

A combinatorial criterion for k-separability of multipartite Dicke states

We derive a combinatorial criterion for detecting k-separability of N-partite Dicke states. The criterion is efficiently computable and implementable without full state tomography. We give examples in which the criterion succeeds, where known criteria fail

Defending Behavior of Peer Victimization in School and Cyber Context During Childhood and Adolescence: A Meta-Analytic Review of Individual and Peer-Relational Characteristics

Adolescent defending of peer victimization in the school and cyber context has received increased attention in developmental science and is an important component of antibullying interventions. However, the overall prevalence, and individual characteristics that correlate with defending in adolescence, have not been systematically and statistically reviewed. Framed in Bronfenbrenner’s social-ecological theory, this meta-analytic review included 172 reports out of 155 studies of defending including 150,978 children and adolescent participants from 4 continents (i.e., North America, Europe, Asia, and Australia) to analyze two aspects: (1) the average proportion of defenders in the population and (2) associations between defending and individual and peer-relational correlates of defending in school and cyber contexts. Using mixed-effects modeling, our results confirmed prior findings of gender differences (favoring girls) and age differences (favoring younger children) in defending. We found positive correlations between defending and affective empathy, cognitive empathy, experiences of peer victimization, self-efficacy, popularity, and acceptance, and a negative correlation between defending and moral disengagement. We also found substantial heterogeneity in these effect sizes. The reporter of defending consistently moderated all mean effect sizes. Implications for prevention efforts and future research are discussed

Multiferroic and Ferroic Topological Order in Ligand-Functionalized Germanene and Arsenene

Two-dimensional (2D) materials that exhibit ferroelectric, ferromagnetic, or topological order have been a major focal topic of nanomaterials research in recent years. The latest efforts in this field explore 2D quantum materials that host multiferroic or concurrent ferroic and topological order. We present a computational discovery of multiferroic state with coexisting ferroelectric and ferromagnetic order in recently synthesized CH2OCH3-functionalized germanene. We show that an electric-field-induced rotation of the ligand CH2OCH3 molecule can serve as the driving mechanism to switch the electric polarization of the ligand molecule, while unpassivated Ge p(z) orbits generate ferromagnetism. Our study also reveals coexisting ferroelectric and topological order in ligand-functionalized arsenene, which possesses a switchable electric polarization and a Dirac transport channel. These findings offer insights into the fundamental physics underlying these coexisting quantum orders and open avenues for achieving states of matter with multiferroic or ferroic-topological order in 2D-layered materials for innovative memory or logic device implementations