Experimental Studies On Control Of Electrons And Phonons In Two-dimensional Materials Based Nanostructures

Since the discovery of atomically-thin graphene in Manchester University in 2004,graphene and graphene-like two-dimensional(2D)materials attracted significant research interests.Outstanding electronic and mechanical properties also make them hot candi-dates for quantum information studies.This paper arranges my studies mainly about experiments on gate-defined quantum dots and nanomechanical resonators based on these materials.The major results are outlined as follows:1.Brief introduction to the properties of two-dimensional materials,and basic con-cepts of gate-defined quantum dots and nanoelectromechanical resonators.2.Introductions to the micro-/nano-fabrication techniques employed in the prepara-tions of molybdenum disulfide(MoS2)based gate-defined double quantum dots and graphene based nanomechanical resonators.Specifically,detailed introduc-tions to dry/wet transfer techniques of 2D materials are provided.3.Experimental studies on gate-defined MoS2 double quantum dot,including sam-ple preparations and characterizations.Wide-range tunability is demonstrated.At low density regime,Coulomb blockade weak antilocalization is observed.4.Experimental studies on graphene based multi-nanomechnical resonators in a chain,including sample preparations and characterizations.Wide-range tunabil-ity is demonstrated.Strong coupling between neighbouring phonon modes is observed.Via tuning the resonant frequency of center phonon cavity,tunable coupling between distant phonon modes is demonstrated.At different coupling strengths,we demonstrate coherent manipulations in the phonon two-level sys-tem formed by distantly coupled two phonon modes.The main innovations of this thesis are:1.First experimental realization of gate-defined double quantum dot based on 2D materials.First observations of Coulomb blockade weak antilocalization in these materials.2.First experimental realization of coupling strength approaching ultra-strong cou-pling regime in neighbouring phonon modes.3.First experimental demonstration of coherent manipulation of phonon two-level system formed by distantly coupled phonon modes,exploring the possibility of phonon databus based on graphene nanomechanical resonator.