Abstract We investigate the enhanced electric dipole–dipole interaction of surface plasmon polaritons (SPPs) supported by a planar metal film waveguide. By taking two nitrogen-vacancy (NV) center electric dipoles in diamond as an example, both the coupling strength and collective relaxation of two dipoles are studied with the numerical Green Function method. Compared to two-dipole coupling on a planar surface, metal film provides stronger and tunable coupling coefficients. Enhancement of the interaction between coupled NV center dipoles could have applications in both quantum information and energy transfer investigation. Our investigation provides systematic results for experimental applications based on a dipole–dipole interaction mediated with SPPs on a planar metal film.
Abstract We investigate the enhanced electric dipole–dipole interaction of surface plasmon polaritons (SPPs) supported by a planar metal film waveguide. By taking two nitrogen-vacancy (NV) center electric dipoles in diamond as an example, both the coupling strength and collective relaxation of two dipoles are studied with the numerical Green Function method. Compared to two-dipole coupling on a planar surface, metal film provides stronger and tunable coupling coefficients. Enhancement of the interaction between coupled NV center dipoles could have applications in both quantum information and energy transfer investigation. Our investigation provides systematic results for experimental applications based on a dipole–dipole interaction mediated with SPPs on a planar metal film.
Precise detection of surface plasmons is crucial for the research of nanophotonics and quantum optics. In this Letter, we used a single nitrogen vacancy center in diamond as a probe to detect the surface plasmon that was tuned by the thickness of a metallic film. The fluorescence intensity and lifetime of the nitrogen vacancy (NV) center were measured to obtain the information of local light-matter interaction. A nonlinear thickness dependent change of the surface plasmon was observed, with the maximum at the thickness of approximately 30 nm. With optimized thickness of silver film, the fluorescence intensity of a single NV center was enhanced 2.6 times, and the lifetime was reduced by a factor of 3, without affecting the coherence time of the NV spin state. The results proved that this system can quantitatively detect the light-matter interaction at nanoscale, and it provides an approach to enhance the fluorescence intensity of a quantum emitter.
The nitrogen-vacancy (NV) center in diamond is very sensitive to magnetic and electric fields, strain, and temperature. In addition, it is possible to optically interrogate individual defects, making it an ideal quantum-limited sensor with nanoscale resolution. A key limitation for the application of NV sensing is the optical brightness and collection efficiency of these defects. Plasmonic resonances of metal nanoparticles have been used in a variety of applications to increase the brightness and efficiency of quantum emitters, and therefore are a promising tool to improve NV sensing. However, the interaction between NV centers and plasmonic structures is largely unexplored. In particular, the back-action between NV and plasmonic nanoparticles is nonlinear and depends on optical wavelength, nanoparticle position, and metal type. Here we present the general theory of NV-plasmonic nanoparticle interactions. We detail how the interplay between NV response, including optical and vibrational signatures, and the plasmonic response of the metal nanoparticle results in modifications to the emission spectra. Our model is able to explain quantitatively the existing experimental measurements of NV centers near metal nanoparticles. In addition, it provides a pathway to developing new plasmonic structures to improve readout efficiencies in a range of applications for the NV center. This will enable higher precision sensors, with greater bandwidth as well as new readout modalities for quantum computing and communication.
) exhibit sharp 4f-4f transitions that are highly sensitive to dipole-dipole interactions (DDIs), yet the intrinsic short-range of DDIs restricts their application in long-distance quantum coupling. Here, we demonstrate a plasmonic nanocavity pair that simultaneously couples to upconversion nanoparticles (UCNPs) and quantum dots (QDs), enabling enhanced emission and inter-emitter interaction. The combined effects of Purcell enhancement and surface plasmon polariton (SPP) propagation extend the DDI-mediated energy transfer over a record distance exceeding 7.5 μm, 2 orders of magnitude longer than conventional Förster resonance systems. Moreover, the polarization-controlled SPP propagation directs the in-plane energy redistribution, achieving anisotropic and tunable coupling. This work establishes a viable route toward controllable, long-range DDIs among rare-earth emitters, advancing integrated quantum photonic architectures.
Abstract We present a comprehensive theoretical study on the controlling of surface plasmon polaritons (SPPs) excitation at the metal–dielectric (silver-Rb atoms) interface using electromagnetically induced transparency (EIT). The results demonstrate that the excitation of SPPs can efficiently be controlled by utilizing the system parameters, e . g . atomic density, pump Rabi frequency and metal thickness. A significant probe field enhancement is achieved by adjusting the pump Rabi frequency and atomic number density, and it can be further optimized by precise tuning of the metal thickness. The resonance angle as well as reflection and transmission of the probe field are found to be highly sensitive to the probe frequency detuning. A notable displacement of the probe transmission peak position is also observed with the increasing pump Rabi frequency. These findings provide tunable control of SPPs using an EIT medium, which may find potential applications in the domains of quantum plasmonic sensor-based devices and quantum communication.
Spontaneous emission (SE) of nitrogen-vacancy centers (NV-centers), which are contained in a single nanodiamond (ND), placed near a silver nanocube, is investigated both experimentally and theoretically. The ND-cube system is assembled with an atomic force microscope, allowing us to directly compare its SE properties to that of the isolated ND. It is demonstrated that the cube coupled NV-centers exhibit strongly polarized SE. For optimal pump laser polarization, the rate of photons is enhanced by a factor of 4.1, with the excited state lifetime being reduced by a factor of 4.1. The enhancement of photon rate is a consequence of local field enhancement of the pump laser, while the SE polarization and lifetime reduction results from coupling of NV-centers to the localized surface plasmon mode of the nanocube. The experimental observations are in qualitative agreement with the model of SE from randomly oriented electric dipoles, allowing us to reveal the underlying physics of the investigated configuration.
Allowing the generation of effective interactions between distant quantum emitters (QEs) via flying photons, quantum interconnect (QI) is essentially a light-matter interface and acts as a building block in quantum technologies. A surface plasmon polariton (SPP) supported by a metallic waveguide provides an ideal interface to explore strong light-matter couplings and to realize QI. However, the loss of SPP in metal makes the mediated entanglement of the QEs damp with the increase of the distance and time, which hinders its applications. We propose a scheme of non-Markovian QI formed by the SPP of a metallic nanowire. A mechanism to make the generated entanglement of the QEs persistent is discovered. We find that, as long as bound states are formed in the energy spectrum of total QE-SPP system, the damping of the SPP-mediated entanglement is overcome even in the presence of the metal absorption to the SPP. Our finding enriches our understanding of light-matter couplings in absorptive medium and paves the way for using the SPP in designing QI.