We investigate relaxation dynamics in the system of two identical quantum dipole emitters (QDEs) located near a metal nanoparticle (MNP) exhibiting a dipolar localized surface plasmon (LSP) resonance at the frequency of the QDE radiative transition. Considering one QDE to be brought into an optically active excited state and weakly coupled to the resonant LSP, we show that a stable superposition state of two QDEs is formed during the transition time, which is much shorter than the QDE spontaneous decay time and determined by the efficiency of resonant interaction between the QDEs and induced LSP. It is elucidated that the superposition state is established as a result of redistribution of the energy of the initially excited QDE so that the corresponding steady-state QDE fields induced at the MNP site cancel each other. The degree of steady-state entanglement characterized by the concurrence is found dependent only on the ratio of distances between the QDEs and the MNP, reaching its maximum value of $\ensuremath{\sim}0.65$, when the separation between the MNP and the initially excited QDE is larger by $\ensuremath{\sim}20%$ than the distance from the other QDE to the MNP.
We develop a general dynamical theory for studying a single-photon transport in a one-dimensional (1D) waveguide coupled to multiple emitters which can be either identical or nonidentical. In this theory, both the effects of the waveguide and non-waveguide vacuum modes are included. This theory enables us to investigate the propagation of an emitter excitation or an arbitrary single-photon pulse along an array of emitters coupled to a 1D waveguide. The dipole-dipole interaction induced by the non-waveguide modes, which is usually neglected in the literature, can significantly modify the dynamics of the emitter system as well as the characteristics of the output field if the emitter separation is much smaller than the resonance wavelength. Nonidentical emitters can also strongly couple to each other if their energy difference is less than or of the order of the dipole-dipole energy shift. Interestingly, if their energy difference is close but nonzero, a very narrow transparency window around the resonance frequency can appear which does not occur for identical emitters. This phenomenon may find important applications in quantum waveguide devices such as optical switches and ultranarrow single-photon frequency comb generator.
We investigate the collective emission spectra and photon correlations of two identical dipole-dipole-coupled emitters under continuous-wave (CW) and periodic pulsed driving. Our results show that a periodic train of instantaneous
πx pulses can generate emission spectra whose dominant features closely resemble those obtained under CW excitation. We find that the structure of the collective emission spectra reflects the interplay among the resonance conditions, dipole-dipole coupling, and the inter-pulse delay
τD. We further demonstrate that finite-duration
πx pulses with sufficiently high Rabi frequencies can closely reproduce the ideal instantaneous-pulse limit. In contrast to the emission spectra, the photon correlations
g(2)(t,τ) are governed primarily by
τD and, unlike under CW driving, become increasingly insensitive to the resonance conditions in the short-pulse limit. These results establish periodic pulsed driving as a versatile means of tailoring both the emission spectra and the photon statistics of coupled two-emitter systems.