We investigated the entanglement between two quantum dots (QDs) with dipole–dipole interaction (DDI) in the waveguide-QD-cavity composite system. It is well-known that if the separation between two QDs is comparable to the resonance wavelength, the DDI between two QDs cannot be ignored and becomes significantly important.
The composite quantum system, as shown in Figure, is composed of a plasmonic waveguide and two QDs that couple to a common cavity.
The total Hamiltonian of the composite system can be decomposed into 6 parts.
The influence of DDI between two QDs on their entanglement was analyzed and the ways to realize the entanglement switching by controlling the frequency of incident surface plasmon (SP) were proposed. Furthermore, the possibilities to achieve highly entangled state of two QDs were also demonstrated in wide range of the SP frequency or the QD-cavity coupling strength by properly adjusting other physical parameters including the resonant frequency of the cavity and the coupling strength of each QD to the waveguide. In particular, we found nearly maximally entangled state independent of the phase difference between two QDs with appropriate values of incident frequency, QD-waveguide coupling strength and so on. In our proposed composite system, the coupling between the QDs and the cavity plays an important part in achieving high entanglement of two QDs which can be used in quantum computing and quantum information processing.
Our paper was published in the "Quantum Information Processing" under the title of "Entanglement of two quantum dots with dipole-dipole interaction coupled to a cavity in plasmonic waveguide system"(https://doi.org/10.1007/s11128-023-04019-9).
