Sökning: "dark photon"

Visar resultat 11 - 15 av 21 avhandlingar innehållade orden dark photon.

1. 11. Microscopic Mechanisms of the Formation, Relaxation and Recombination of Excitons in Two-Dimensional Semiconductors

   Författare :Samuel Brem; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; relaxation dynamics; 2D materials; density matrix formalism; excitons; exciton-phonon interaction; Bloch equations;

   Sammanfattning : Monolayers of Transition Metal Dichalcogenides (TMDs) present a giant leap forward towards the realization of semiconductor devices with atomic scale thickness. As a natural consequence of their two-dimensional character TMDs exhibit a reduced dielectric screening, leading to the formation of unusually stable excitons, i.e. LÄS MER

3. 12. Axionlike particles, quantum loops, and supernovae : The role of quantum loop corrections for astrophysical ALPs

   Författare :Eike Christoph Müller; David Marsh; Frank Wilczek; Bo Sundborg; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Theoretical Physics; teoretisk fysik;

   Sammanfattning : In this thesis the quantum field theory and astrophysical phenomenology of axionlike particles (ALPs) are studied. The effective field theory of ALPs is reviewed with a special focus on quantum loops, the renormalization group equations, and the equivalent forms of the interaction between ALPs and fermions. LÄS MER

4. 13. Pulse Generation and Detection through Intra-Cavity Up-Conversion

   Författare :Max Widarsson; Fredrik Laurell; Valdas Pasiskevicius; Peter Tidemand-Lichtenberg; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Optik och fotonik; Optics and Photonics;

   Sammanfattning : The work presented in this thesis concerns two main categories: pulse detection and pulse generation, however both utilise intra-cavity up-conversion. The work regarding pulse detection deals with up-conversion LIDAR and was split into two smaller projects, the first one focused on the resolution in measurements along one line with multiple reflections, and the second focused on measurements further into the MIR, as well as performing 3D imaging. LÄS MER

5. 14. Type-II interband quantum dot photodetectors

   Författare :Oscar Gustafsson; Mattias Hammar; Wenquan Ma; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; photodetector; quantum dot; infrared; MOVPE; thermal imaging; type-II; photoluminescence; III V; InSb; InGaSb; InAs; SRA - ICT; SRA - Informations- och kommunikationsteknik;

   Sammanfattning : Photon detectors based on single-crystalline materials are of great interest for high performance imaging applications due to their low noise and fast response. The major detector materials for sensing in the long-wavelength infrared (LWIR) band (8-14 µm) are currently HgCdTe (MCT) and AlGaAs/GaAs quantum wells (QW) used in intraband-based quantum-well infrared photodetectors (QWIPs). LÄS MER

7. 15. Electron dynamics in graphene in the presence of an electrical field

   Författare :Roland Jago; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Bloch equations; density matrix formalism; graphene; relaxation dynamics; photoconduction effect; carrier multiplication;

   Sammanfattning : Graphene as atomically thin two-dimensional material exhibits remarkableoptical and electronic properties that suggest its technological applicationin novel optoelectronic devices, such as graphene-based lasers and photodetectors.The linear electronic bandstructure and the vanishing band gap atthe Dirac point open up new relaxation channels, such as Auger scattering. LÄS MER