Plasmon-induced Quantum Correlation And Energy Transfer Between Molesules

In recent years,the interactions between surface plasmons of metallic nanostructures and quantum emitters like atoms,molecules and quantum dots have been the research hotspots of quantum optics.Metallic nanoparticle possesses many unique properties;for instance,the electromagnetic fields can be confined in the surface of the nanoparticle due to the excitation of plasmons.The interactions between quantum emitters and different electromagnetic excitation modes of nanoparticle can arise novel phenomena.More interestingly,in the closely spaced metal nanoparticle systems,coupling resonance modes could be excited.These coupling resonance modes can cause rich correlation effects between quantum emitters.This thesis explores the quantum correlation and energy transfer induced by interactions between multiple quantum emitters and nanoparticle cluster.Firstly,we give the full quantum theory of interaction between multiple two-level systems and surface plasmons of single nanoparticle,construct superradiance and subradiance between multiple atoms,and realize multi-qubit quantum phase gates.Due to large dissipation in metal,the fidelities of these phase gates are small.We find that by coating the metal particle with a layer of gain,the fidelities can be improved.In addition,we use a graphene wrapped dielectric particle to realize tunable quantum phase gates.These phase gates have the advantage of sensitive adjustability by changing the Fermi level or the electrostatic gating in graphene.At the same time they possess very high fidelities due to the small dissipation in the graphene monolayer.Next,by using electromagnetic Green's tensor technique,we have developed a theoretical method to study the strong coupling between an ensemble of quantum emitters and surface plasmons excited by the nanoparticle cluster,and investigated the multi-qubit entanglement.Our research shows: multi-qubit entanglement has many advantages compared to other systems.For example,the multi-qubit entanglement for two-level emitters can be produced at different frequencies simultaneously when they are located in the hotspots of metallic nanoparticle clusters.The duration of quantum beats for such an entanglement can reach two orders longer than that for the entanglement in the photonic cavity.The phenomena originate from collective excitations of coupling resonances in the cluster.And then,the F?rster resonance energy transfer(FRET)rate and efficiency of an excited donor and a ground-state acceptor located in the gaps of a nanoparticle cluster have been studied by using a rigorous multiscattering electromagnetic static Green's tensor technique.A nonlocal effect has been considered by using the hydrodynamic model.It has been found that the FRET rate and efficiency can be enhanced simultaneously by more than 9 and 3 orders of magnitude at suitable parameters,respectively.The phenomenon originated in the coupling plasmonic resonances.This provides a way to realize the energy transfer process with simultaneously ultrafast and ultrahigh efficiency.Furthermore,various dependences of the FRET rate on the LDOS have been observed in the same system under different conditions.At the coupling resonances,the dependence changes from linear to exponential.At the single scattering resonance,the energy transfer rate is almost independent of the LDOS.At last,we have theoretically investigated the coherent energy transfer of a pair of donor and acceptor molecules located in the gaps of three nanoparticles.We find that,in coupling resonance region,both coherent and incoherent coupling could be very strong induced by plasmons when the gap is small,and coherent coupling can increase energy transfer efficiency and reduce energy transfer time.Thus we can realize ultrafast energy transfer with high efficiency.