Platinum diselenide () is a promising two‐dimensional (2D) material for the terahertz (THz) range... more Platinum diselenide () is a promising two‐dimensional (2D) material for the terahertz (THz) range as, unlike other transition metal dichalcogenides (TMDs), its bandgap can be uniquely tuned from a semiconductor in the near‐infrared to a semimetal with the number of atomic layers. This gives the material unique THz photonic properties that can be layer‐engineered. Here, we demonstrate that a controlled THz nonlinearity—tuned from monolayer to bulk —can be realized in wafer size polycrystalline through the generation of ultrafast photocurrents and the engineering of the bandstructure valleys. This is combined with the layer interaction with the substrate for a broken material centrosymmetry, permitting a second order nonlinearity. Further, we show layer dependent circular dichroism, where the sign of the ultrafast currents and hence the phase of the emitted THz pulse can be controlled through the excitation of different bandstructure valleys. In particular, we show that a semimetal ha...
Strong polarization-dependent effects on the optical response in the low-symmetry orthorhombic cr... more Strong polarization-dependent effects on the optical response in the low-symmetry orthorhombic crystal structure of GeS and the emergence of mixed exciton states due to anisotropy-induced symmetry breaking.
We have studied theoretically the electronic structure of Si δ-doped layer inserted into an infin... more We have studied theoretically the electronic structure of Si δ-doped layer inserted into an infinite quantum well as dependent on the applied electric field. The semiconductor was GaAs and delta doping was assumed to be formed by Si atoms with a uniform distribution in the delta layer. We use an efficient self-consistent procedure to solve simultaneously the Schrödinger and Poisson
Developing photothermal solar driven membrane distillation (PSDMD) is of great importance in prov... more Developing photothermal solar driven membrane distillation (PSDMD) is of great importance in providing fresh water for remote off-grid regions. The production of freshwater through the PSDMD is driven by the temperature difference between feed and distillate sides created via the addition of efficient photothermal nanostructures. Here we proposed nickel sulfides and nickel tellurium nanoparticles (NPs) to be loaded into the polymeric membrane to enhance its performance. Ag and CuSe NPs are also considered for comparison as they are previously used for membrane distillation (MD). Our theoretical approach showed that all of the considered NPs increased the temperature of the PVDF membrane by around a few degrees. NiS and NiTe2 NPs are the most efficient solar light-to-heat converters compared to NiTe and NiS2 NPs due to their efficient absorption over the visible range. PVDF membrane loaded with 25% of NiCs NPs and a porosity of 32% produced a transmembrane vapor flux between 22 and 2...
arXiv: Mesoscale and Nanoscale Physics, Nov 23, 2021
A successful and promising device for the physical implementation of electron spin-valley based q... more A successful and promising device for the physical implementation of electron spin-valley based qubits is the Transition Metal Dichalcogenide monolayer (TMD-ML) semiconductor quantum dot. The electron spin in TMD-ML semiconductor quantum dots can be isolated and controlled with high accuracy, but it still suffers from decoherence due to the unavoidable coupling with the surrounding environment, such as nuclear spin environments. A common tool to investigate systems like the one considered in this work is the density matrix formalism by presenting an exact master equation for a central spin (spin-qubit) system in a time-dependent and coupled to a nuclear spin bath in terms of hyperfine interaction. The master equation provides a unified description of the dynamics of the central spin. Analyzing this in more detail, we calculate fidelity loss due to the Overhauser field from hyperfine interaction in a wide range number of nuclear spins $\mathcal{N}$.
Platinum diselenide () is a promising two‐dimensional (2D) material for the terahertz (THz) range... more Platinum diselenide () is a promising two‐dimensional (2D) material for the terahertz (THz) range as, unlike other transition metal dichalcogenides (TMDs), its bandgap can be uniquely tuned from a semiconductor in the near‐infrared to a semimetal with the number of atomic layers. This gives the material unique THz photonic properties that can be layer‐engineered. Here, we demonstrate that a controlled THz nonlinearity—tuned from monolayer to bulk —can be realized in wafer size polycrystalline through the generation of ultrafast photocurrents and the engineering of the bandstructure valleys. This is combined with the layer interaction with the substrate for a broken material centrosymmetry, permitting a second order nonlinearity. Further, we show layer dependent circular dichroism, where the sign of the ultrafast currents and hence the phase of the emitted THz pulse can be controlled through the excitation of different bandstructure valleys. In particular, we show that a semimetal ha...
Strong polarization-dependent effects on the optical response in the low-symmetry orthorhombic cr... more Strong polarization-dependent effects on the optical response in the low-symmetry orthorhombic crystal structure of GeS and the emergence of mixed exciton states due to anisotropy-induced symmetry breaking.
We have studied theoretically the electronic structure of Si δ-doped layer inserted into an infin... more We have studied theoretically the electronic structure of Si δ-doped layer inserted into an infinite quantum well as dependent on the applied electric field. The semiconductor was GaAs and delta doping was assumed to be formed by Si atoms with a uniform distribution in the delta layer. We use an efficient self-consistent procedure to solve simultaneously the Schrödinger and Poisson
Developing photothermal solar driven membrane distillation (PSDMD) is of great importance in prov... more Developing photothermal solar driven membrane distillation (PSDMD) is of great importance in providing fresh water for remote off-grid regions. The production of freshwater through the PSDMD is driven by the temperature difference between feed and distillate sides created via the addition of efficient photothermal nanostructures. Here we proposed nickel sulfides and nickel tellurium nanoparticles (NPs) to be loaded into the polymeric membrane to enhance its performance. Ag and CuSe NPs are also considered for comparison as they are previously used for membrane distillation (MD). Our theoretical approach showed that all of the considered NPs increased the temperature of the PVDF membrane by around a few degrees. NiS and NiTe2 NPs are the most efficient solar light-to-heat converters compared to NiTe and NiS2 NPs due to their efficient absorption over the visible range. PVDF membrane loaded with 25% of NiCs NPs and a porosity of 32% produced a transmembrane vapor flux between 22 and 2...
arXiv: Mesoscale and Nanoscale Physics, Nov 23, 2021
A successful and promising device for the physical implementation of electron spin-valley based q... more A successful and promising device for the physical implementation of electron spin-valley based qubits is the Transition Metal Dichalcogenide monolayer (TMD-ML) semiconductor quantum dot. The electron spin in TMD-ML semiconductor quantum dots can be isolated and controlled with high accuracy, but it still suffers from decoherence due to the unavoidable coupling with the surrounding environment, such as nuclear spin environments. A common tool to investigate systems like the one considered in this work is the density matrix formalism by presenting an exact master equation for a central spin (spin-qubit) system in a time-dependent and coupled to a nuclear spin bath in terms of hyperfine interaction. The master equation provides a unified description of the dynamics of the central spin. Analyzing this in more detail, we calculate fidelity loss due to the Overhauser field from hyperfine interaction in a wide range number of nuclear spins $\mathcal{N}$.
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Papers by sihem jaziri