M. Karam Ouharou

Coherent Simulation of Correlated Electron Systems using Hole Spins in Germanium Quantum Dots   Abstract: Simulating condensed matter systems beyond the capabilities of classical computers is a promising avenue for advancing our understanding of quantum phenomena. Quantum dots and donors in semiconductor technology offer a natural platform for implementing quantum simulation. While various material platforms have been explored for studying interacting charge and spin states, the challenge of decoherence has limited the realization of coherent quantum dynamics. In this study, we introduce quantum simulation using hole spins in germanium quantum dots, showcasing extensive and coherent control over multi-spin states in isolated, paired, and fully coupled quantum dots. Specifically, we focus on simulating resonating valence bonds (RVBs) and measure the evolution between singlet product states, which remains coherent over many periods. Additionally, we demonstrate the realization of fou...

 Excitonic Topological Order in Imbalanced Electron-Hole Bilayers Abstract:   Excitonic topological order, arising from the interplay of strong Coulomb interactions and the quantum confinement of charge carriers, has recently emerged as a fascinating avenue for exploring novel quantum phenomena. In this article, we delve into the concept of excitonic topological order in imbalanced electron-hole bilayers. We discuss the underlying principles, experimental observations, and potential applications of this intriguing quantum state.

Fig 1.1 : fentes de Young   La célèbre expérience des doubles fentes, qui a démontré que la lumière est à la fois une onde et une particule, a été réalisée en utilisant des "fentes temporelles". Les méthodes utilisées constituent une nouvelle façon de manipuler la lumière qui pourrait être utilisée pour créer des matériaux étranges appelés "cristaux de temps". L'expérience des doubles fentes, réalisée pour la première fois par Thomas Young en 1801, consiste à envoyer un faisceau de lumière sur une plaque ou une carte dans laquelle deux petites fentes ont été découpées pour laisser passer la lumière. Lorsque les ondes lumineuses passent à travers les fentes, elles interfèrent l'une avec l'autre, provoquant un motif de bandes claires et sombres sur un écran. Ce phénomène ne serait pas possible si la lumière était simplement constituée de particules. Cette expérience a donc été l'une des premières preuves que la lumière est également une onde. Alors que...

Laser Cooling Starting in about 1985 with the work of Steven Chu and others, the use of lasers to achieve extremely low temperatures has advanced to the point that temperatures of 10-9 K have been reached. If an atom is traveling toward a laser beam and absorbs a photon from the laser, it will be slowed by the fact that the photon has momentum p = E/c = h/λ. If we take a sodium atom as an example, and assume that a number of sodium atoms are freely moving in a vacuum chamber at 300K, the rms velocity of a sodium atom from the Maxwell speed distribution would be about 570 m/s. Then if a laser is tuned just below one of the sodium d-lines (589.0 and 589.6 nm, about 2.1 eV), a sodium atom traveling toward the laser and absorbing a laser photon would have its momentum reduced by the amount of the momentum of the photon. It would take a large number of such absorptions to cool the sodium atoms to near 0K since one absorption would slow a sodium atom by only about 3 cm/s out of a speed of 5...