Topological states on the breathing kagome lattice

We theoretically study the topological properties of the tight-binding model on the breathing kagome lattice with antisymmetric spin-orbit coupling (SOC) between nearest neighbors. We show that the system hosts nontrivial topological phases even without second-nearest-neighbor hopping, and that the weakly dispersing band of the kagome lattice can become topological. The main results are presented in the form of phase diagrams, where the $\mathbb{Z}_2$ topological index is shown as a function of SOC (intrinsically allowed and Rashba) and lattice trimerization. In addition, exact diagonalization is compared with effective low-energy theories around the high-symmetry points. We find that the weakly dispersing band has a very robust topological property associated with it. Moreover, the Rashba SOC can produce a topological phase rather than hinder it, in contrast to the honeycomb lattice. Finally, we consider the case of a fully spin polarized (ferromagnetic) system, breaking time-reversal symmetry. We find a phase diagram that includes systems with finite Chern numbers. In this case too, the weakly dispersing band is topologically robust to trimerization.Comment: 8 pages, 6 figures; published versio

Reinforcement Learning for Digital Quantum Simulation

Digital quantum simulation is a promising application for quantum computers. Their free programmability provides the potential to simulate the unitary evolution of any many-body Hamiltonian with bounded spectrum by discretizing the time evolution operator through a sequence of elementary quantum gates, typically achieved using Trotterization. A fundamental challenge in this context originates from experimental imperfections for the involved quantum gates, which critically limits the number of attainable gates within a reasonable accuracy and therefore the achievable system sizes and simulation times. In this work, we introduce a reinforcement learning algorithm to systematically build optimized quantum circuits for digital quantum simulation upon imposing a strong constraint on the number of allowed quantum gates. With this we consistently obtain quantum circuits that reproduce physical observables with as little as three entangling gates for long times and large system sizes. As concrete examples we apply our formalism to a long range Ising chain and the lattice Schwinger model. Our method makes larger scale digital quantum simulation possible within the scope of current experimental technology.Comment: 5 pages, 3 figure

Le garum en al-Andalus un feu trouvé au fond des mers

Sin resume

Le déplacement de l’intentionnalité chez Darwin

En appliquant la théorie évolutionniste à l’étude de l’expression des émotions, Darwin modifie le champ de l’observation pour y inclure l’expression chez les animaux. Il change alors le sens des mots volonté, conscience, intention sur lesquels se fondaient les créationnistes pour faire des expressions le reflet de l’âme. En insistant au contraire sur le caractère habituel, involontaire et inconscient des expressions, Darwin découvre les zones obscures de la psyché humaine plus tard explorées par Freud.The Darwinian Shift in Intentionality. — By applying the theory of evolution to the study of how emotions are expressed, Darwin modified the field of observation so as to include animals. He thus changed the meanings of will, conscience and intention, notions that creationists used to present emotions as the soul’s reflection. By emphasizing the habitual, involuntary and unconscious nature of feelings, Darwin discovered the obscure zones in the human mind that Freud would later explore

La vergogne dans la légende de Lucrèce de l’Antiquité à la Renaissance

La vergogne désigne une catégorie d’émotions qui inhibent des impulsions dommageables pour les liens sociaux. Les formes spécifiques de ces inhibiteurs d’impulsions relèvent des codes sociaux et des systèmes de valeurs en vigueur dans le groupe auquel appartient la personne. La personne est censée avoir intériorisé ces codes et ces valeurs, et exprime leur force par l’inhibition d’impulsions que le système social cherche à canaliser. La légende de Lucrèce, reprise de l’Antiquité jusqu’à la Renaissance, permet d’observer les modulations de cette problématique en fonction du système conceptuel actif dans chacune des œuvres qui sont abordées, soit les différentes versions de la légende de Lucrèce par Tite-Live, Ovide, saint Augustin, John Gower, Geoffrey Chaucer et William Shakespeare.Vergogne refers to a category of emotions that inhibit impulses which are detrimental to social relationships. The specific forms of these impulse inhibitors pertain to the social codes and value systems active in a social group. Such codes and values are expected to be internalized by social members and to express their force by effectively channelling the impulses to be controlled. The Legend of Lucrece, reinterpreted from the Antiquity to the Renaissance, evinces such a problematic through the modulations of the different conceptual systems used within the various versions of the Legend under study, written by Livy, Ovid, Saint Augustine, John Gower, Geoffrey Chaucer and William Shakespeare