Article

Akimov, A. V. et al. Generation of single optical plasmons in metallic nanowires coupled to quantum dots. Nature 450, 402-406

Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA.
Nature (Impact Factor: 41.46). 12/2007; 450(7168):402-6. DOI: 10.1038/nature06230
Source: PubMed

ABSTRACT

Control over the interaction between single photons and individual optical emitters is an outstanding problem in quantum science and engineering. It is of interest for ultimate control over light quanta, as well as for potential applications such as efficient photon collection, single-photon switching and transistors, and long-range optical coupling of quantum bits. Recently, substantial advances have been made towards these goals, based on modifying photon fields around an emitter using high-finesse optical cavities. Here we demonstrate a cavity-free, broadband approach for engineering photon-emitter interactions via subwavelength confinement of optical fields near metallic nanostructures. When a single CdSe quantum dot is optically excited in close proximity to a silver nanowire, emission from the quantum dot couples directly to guided surface plasmons in the nanowire, causing the wire's ends to light up. Non-classical photon correlations between the emission from the quantum dot and the ends of the nanowire demonstrate that the latter stems from the generation of single, quantized plasmons. Results from a large number of devices show that efficient coupling is accompanied by more than 2.5-fold enhancement of the quantum dot spontaneous emission, in good agreement with theoretical predictions.

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Available from: Alexey Akimov, Aug 31, 2015
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    • "Waveguide configurations supporting the SPP propagation , i.e., plasmonic waveguides, exhibit (at least, in some cases) a unique feature of guiding SPP modes with extreme confinement, far beyond the diffraction limit [29]. This opens a way to realize a very efficient coupling of emitters to these SPP guided modes [30] [31] [32]. Channel plasmon polariton (CPP) modes supported by VGs cut into metal are especially suited for efficient coupling to emitters due to their strong confinement and relatively long propagation lengths [28] [33] [34]. "
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    ABSTRACT: Nitrogen-vacancy (NV) centers in diamonds are interesting due to their remarkable characteristics that are well suited to applications in quantum-information processing and magnetic field sensing, as well as representing stable fluorescent sources. Multiple NV centers in nanodiamonds (NDs) are especially useful as biological fluorophores due to their chemical neutrality, brightness and room-temperature photostability. Furthermore, NDs containing multiple NV centers also have potential in high-precision magnetic field and temperature sensing. Coupling NV centers to propagating surface plasmon polariton (SPP) modes gives a base for lab-on-a-chip sensing devices, allows enhanced fluorescence emission and collection which can further enhance the precision of NV-based sensors. Here, we investigate coupling of multiple NV centers in individual NDs to the SPP modes supported by silver surfaces protected by thin dielectric layers and by gold V-grooves (VGs) produced via the self-terminated silicon etching. In the first case, we concentrate on monitoring differences in fluorescence spectra obtained from a source ND, which is illuminated by a pump laser, and from a scattering ND illuminated only by the fluorescence-excited SPP radiation. In the second case, we observe changes in the average NV lifetime when the same ND is characterized outside and inside a VG. Fluorescence emission from the VG terminations is also observed, which confirms the NV coupling to the VG-supported SPP modes.
    Full-text · Article · Dec 2015 · Journal of optics
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    • "Nanoguides have been used to couple light to single quantum dots [17] [18] [19], atoms [20] [21], color centers [22], molecules [23] [24] and superconducting qubits [25] [26]. On the theoretical side, the interaction of light and quantum emitters in a nanoguide has been studied for obtaining Bragg cavities [27], coupling two atoms via a photonic channel [28] or realizing photon-photon interaction via an atom [27, 29]. "
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    ABSTRACT: Propagation of light through dielectrics lies at the heart of optics. However, this ubiquitous process is commonly described using phenomenological dielectric function $\varepsilon$ and magnetic permeability $\mu$, i.e. without addressing the quantum graininess of the dielectric matter. Here, we present a theoretical study where we consider a one-dimensional ensemble of atoms in a subwavelength waveguide (nanoguide) as fundamental building blocks of a model dielectric. By exploring the roles of the atom-waveguide coupling efficiency, density, disorder, and dephasing, we establish connections among various features of polaritonic light-matter states such as localization, super and subradiance, and strong coupling. In particular, we show that coherent multiple scattering of light among atoms that are coupled via a single propagating mode can gives rise to Rabi splitting. These results provide important insight into the underlying physics of strong coupling reported by recent room-temperature experiments with microcavities and surface plasmons.
    Full-text · Article · Oct 2015
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    • "The 1D strong-coupling regime, where the light-matter interaction dominates over loss and dephasing, provides an excellent setting in which to investigate interesting quantumoptical effects theoretically [3–5, 7–34], observe such effects experimentally, [35] [36] [37] [38] [39] [40] [41] [42] [43] [44] [45] [46] [47] [48] [49], construct building blocks of quantum information processing and quantum computing [4, 7, 14, 50– 57], and generate qubit-qubit entanglement [24, 58–63]. A variety of artificial systems have been proposed and realized to implement light-matter interaction in 1D, including superconducting qubits coupled to a microwave transmission line [35] [36] [37] [38] [39] [40] [41] [42] [43] [44] [45] [46] [47] [48] [49] and semiconductor quantum dots coupled to either a metallic nanostructure [64] [65] [66] or a photonic-crystal waveguide [67] [68] [69]. In addition to artificial atoms, waveguide QED can also be implemented using an ion trap [70], cold atoms trapped in [71] or near [72] an optical fiber, or single molecules doped in an organic crystal filled in a glass capillary [73]. "
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    ABSTRACT: We study two-level systems (2LS) coupled at different points to a one-dimensional waveguide in which one end is open and the other is either open (infinite waveguide) or closed by a mirror (semi-infinite). Upon injection of two photons (corresponding to weak coherent driving), the resonance fluorescence and photon correlations are shaped by the effective qubit transition frequencies and decay rates, which are substantially modified by interference effects. In contrast to the well-known result in an infinite waveguide, photons reflected by a single 2LS coupled to a semi-infinite waveguide are initially bunched, a result that can be simply explained by stimulated emission. As the number of 2LS increases (up to 10 are considered here), rapid oscillations build up in the correlations that persist for a very long time. For instance, when the incoming photons are slightly detuned, the transmitted photons in the infinite waveguide are highly antibunched. On the other hand, upon resonant driving, incoherently reflected photons are mostly distributed within the photonic band gap and several sharp side peaks. These features can be explained by considering the poles of the single particle Green function in the Markovian regime combined with the time delay. Our calculation is not restricted to the Markovian regime, and we obtain several fully non-Markovian results. We show that a single 2LS in a semi-infinite waveguide can not be decoupled by placing it at the node of the photonic field, in contrast to recent results in the Markovian regime. Our results illustrate the complexities that ensue when several qubits are strongly coupled to a bus (the waveguide) as might happen in quantum information processing.
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