In order to obtain an electrostatic control of the valley polarization of incoming electrons, we deposited local gates at the intersections between the pn junction and the graphene physical edge. For this aim, we used, in the quantum Hall regime, a graphene pn junction, formed thanks to gates deposited on top of a stack composed of a graphene sheet encapsulated in Boron nitride crystals. In a first part, this PhD work deals with the coherent manipulation of the valley, which is necessary to achieve a valley quantum bit in graphene. In 2005, the discovery of a novel material, graphene, opened new prospects with on one hand the prediction of a larger phase coherence, and on the other hand the existence, in addition to the spin, of a new degree of freedom, named the valley, giving access to new possibilities to encode information. This fragility makes it difficult to achieve entangled states and limits the development of complex quantum computations. Up to now, the experiments carried out in semi-conducting GaAs/AlGaAs heterostructures exhibited the possibility to encode information in the charge or the spin of an electron, but strong decoherence in these systems implies a great weakness of these quantum states, which survives only below temperatures of 100mK and electrical biases of 40μV. In this context, one of the main stakes is the achievement of quantum bits using electronic states, as well as the creation of entangled electronic states, which are the building blocks to achieve complex quantum computations. the realization of the electronic analogue of quantum optics experiments, represents a developing and recent research field, offering interesting perspectives for quantum computing. Finally, the generation technique could be applied to cold atomic gases, leading to the possibility of atomic levitons.Įlectron quantum optics, i.e. But they can also carry a fraction of charge if they are implemented in Luttinger liquids or in fractional quantum Hall edge channels this allows the study of Abelian and non-Abelian quasiparticles in the time domain. Levitons are not limited to carrying a single charge, and so in a broader context n-particle levitons could find application in the study of full electron counting statistics. Compared with electron sources based on quantum dots, the generation of levitons does not require delicate nanolithography, considerably simplifying the circuitry for scalability. The latter, obtained by colliding synchronized levitons on a beam splitter, exemplifies the potential use of levitons for quantum information: using linear electron quantum optics in ballistic conductors, it is possible to imagine flying-qubit operation in which the Fermi statistics are exploited to entangle synchronized electrons emitted by distinct sources. Further identification of levitons is provided in the energy domain with shot-noise spectroscopy, and in the time domain with electronic Hong-Ou-Mandel noise correlations. Minimal-excitation states are observed for Lorentzian pulses, whereas for other pulse shapes there are significant contributions from holes. Partitioning the excitations with an electronic beam splitter generates a current noise that we use to measure their number. Here we report that such quasiparticles (hereafter termed levitons) can be generated on demand in a conductor by applying voltage pulses to a contact. However, it was predicted nearly 20 years ago that a Lorentzian time-dependent potential with quantized flux generates a minimal excitation with only one particle and no hole. This is because any perturbation affects all states below the Fermi energy, resulting in a complex superposition of particle and hole excitations. In 2007, the Tear Film and Ocular Surface Society (TFOS) published the Report of the TFOS International Dry Eye Workshop, later known as TFOS DEWS.The on-demand generation of pure quantum excitations is important for the operation of quantum systems, but it is particularly difficult for a system of fermions. Global Programs and Resources for National Societies.Minority Ophthalmology Mentoring Campaign.Subspecialty/Specialized Interest Society Meetings.Subspecialty/Specialized Interest Society Directory.International Blindness Prevention Award.Provider Enrollment, Chain and Ownership System (PECOS).Ophthalmic Coding Specialist (OCS) Exam.What Practices Are Saying About the Registry.LEO Continuing Education Recognition Award.Pediatric Ophthalmology Education Center.Program Participant and Faculty Guidelines.Instruction Courses and Skills Transfer Labs.My Dashboard My Education Find an Ophthalmologist.
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