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Spontaneous emission of luminescent material is strongly dependent on the surrounding electromagnetic environment. To enhance the emission rate of a single-photon emitter, we proposed a wire-groove resonant nanocavity around the single-photon emitter. An InGaAs quantum dot embedded in a GaAs nanowire was employed as a site-control single-photon emi...
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Control of quantum matter through resonant electromagnetic cavities is a promising route towards establishing control over material phases and functionalities. Quantum paraelectric insulators -- materials which are nearly ferroelectric -- are particularly promising candidate systems for this purpose since they have strongly fluctuating collective m...
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... QDNWs are studied as ideal candidates for single photon emitters to achieve nearunity light extraction efficiency (Friedler et al. 2009). There is considerable interest in these structures because of their potential application as single photon sources with large extraction efficiency, long coherent time, higher directionality, and photon indistinguishability (Wei et al. 2019;Tatebayashi et al. 2015;Otnes and Borgström 2017;Haffouz et al. 2018). For instance, Claudon et al. (2010) have adopted an approach, based on an InAs quantum dot embedded in a GaAs photonic nanowire with carefully tailored ends as a highly efficient single-photon source. ...
The quantum dots embedded in nanowires are of great interest for their applications in nanolasers and quantum emitters. In this regard, the electronic confined states and optical properties of an InAs conical quantum dot located on an InAs wetting layer and embedded in an infinite GaAs nanowire are investigated theoretically. This is accomplished by numerically solving the Schrodinger equation using the effective mass approximation. The results show the existence of an energy continuum for each cannel of angular momentum whose lower limit raises by the angular momentum. This causes discrete bound states of higher angular momentum to lie in the continuum of the lower ones. On the other hand, although the confined energy levels decrease smoothly by increasing the nanowire radius, their decline by dot radius and height represents some step-like features. This effect could be explained based on the relative concentration of the electron probability density in the dot and wetting layer. Finally the oscillation strength for intersubband transition between confined energy states of the system have been investigated.
... The Purcell effect enhancement is obtained by controlling the coupling of the cavity and the environment [13]. Moreover, the spontaneous emission rate can be enhanced through geometrical design of the cavity [14,15,16], or photon phase filters [17]. ...
We perform theoretical calculations to study steady-state electron transport in a double quantum dot, DQD, coupled to a quantized cavity photon field both in resonance and off-resonance regimes considering weak and strong coupling. In the resonant strong coupling regime, photon exchanges between the energy states of the DQD and the cavity are found reflecting multiple Rabi-resonances. The electron occupation of the states and the transport current can be smoothly increased by tuning the cavity-environment coupling strength. Making the system off-resonant, but still in the strong coupling regime, the photon exchange is diminished and the electron occupation of the system and the transport current through it are prominent for high cavity-environment coupling strength. In the weak coupling regime between the DQD and the cavity, the system has almost the same response in the resonant and the off-resonant regimes at high values of the cavity-environment coupling strength.
... [9] The corresponding emission rate of 100 MHz would thus be too low for a wide range of applications desiring much higher generation rates. [9,10] Placing QDs into an environment with increased electromagnetic local density of optical states (LDOS) can drastically enhance the SE rate of SPEs through the Purcell The authors would like to thank Professor Markus Raschke for his suggestion on the paper. This work was supported by NSFC (62005037) effect. ...
... According to the Fermi's golden rule, the SE rate of the transmitter is proportional to the LDOS. [10] Therefore, the Fp gradually returns to the normal value, equivalent to the Fp of a single NWQD due to the decreased LDOS, as shown in the inset of Fig. 3(e). The two peaks of Fp in Fig. 3(e) at d ≈ 180 nm and d ≈ 260 nm correspond to the two peaks in Fig. 2(a), which result from the single-mode and multi-mode of a single nanowire. ...
... It is worth noting that the non-radiative ohmic loss induced by the bowtie is small, i.e., 5%, while the narrow metal slit structures have been reported with above 80% non-radiative ohmic loss. [10,33,34] The emission of NWDQ can either be coupled to the far-field via plasmonic bowtie or quench via ohmic losses. The bowtie nanoantenna provides a good balance between enhancement and losses for QD emission applications. ...
Integration of a single III-V quantum dot with a plasmonic nanoantenna is still underexplored as a means towards efficient single-photon sources. Here, we propose two new concepts based on a nanowire quantum dot (NWQD) emitter coupled with a plasmonic bowtie antenna and an NWQD-plasmonic metal hybrid structure. Based on finite element method modeling, we show how these devices can achieve an enhancement in single-photon emission rate and directional radiation. The plasmonic bowtie can increase the spontaneous emission of NWQD with a small diameter, overcoming their otherwise dominating intrinsic spontaneous emission suppression. Further, the NWQD-plasmonic hybrid structure can act as a single-mode waveguide. These features would facilitate nano-photonic device integration as desired for applications of bright single-photon sources, plasmonic lasers, and on-chip opto-electronic nanodevices.
... compared to all-dielectric structures, reaching the ultimate level of single-photon emission of the order of 1 THz. Recently, experimental demonstrations of ultrafast roomtemperature single-photon emission with rates up to 80 GHz from quantum dots coupled to plasmonic nanostructures have been reported [10,11]. ...
... ρ ++ = γ + ρ UU − + ρ ++ (11) and the equations for the coherencies of interest: ...
Single-photon sources are subjected to a fundamental limitation in the speed of operation dictated by the spontaneous emission rate of quantum emitters (QEs). The current paradigm of the rate acceleration suggests coupling of a QE to a metal nanostructure, in particular, a metal nanoparticle (MNP). Here, we demonstrate that, in contrast to this approach, a MNP itself being excited via a strong coupling with a QE can emit light with quantum properties. We determine both the first- and second-order correlation functions of light spontaneously emitted by a MNP in such a compound and show that this light should exhibit sub-Poissonian photon statistics and perfect photon antibunching. This discovery opens a prospect to single-photon sources with generation rates up to 100 THz.
... In cavity QED, the spontaneous emission rate is characterized by the mode density of the quantized photon field which is known as the Purcell effect in the context of cavity QED. Recently, a QD system was used to enhance the spontaneous emission by a single photon nanocavity coupled to the environment [18], where the coherency of the single photon source should be maintained [19,20]. ...
We theoretically investigate the characteristics of the electron transport through a two-dimensionala quantum dot system in the $xy$-plane coupled to a photon cavity and a photon reservoir, the environment. The electron-photon coupling, $g_{\gamma}$, and the cavity-reservoir coupling, $\kappa$, are tuned to study the system in the weak, $g_{\gamma} \leq \kappa$, and the strong coupling regime, $g_{\gamma} > \kappa$. An enhancement of current is both seen with increasing $g_{\gamma}$ and $\kappa$ in the weak coupling regime for both $x$- and $y$-polarization of the photon field. This is a direct consequence of the Purcell effect. The current enhancement is due to the contribution of the photon replica states to the electron transport in which intraband transitions play an important role. The properties of the electron transport are drastically changed in the strong coupling regime with an $x$-polarized photon field in which the current is suppressed with increasing $g_{\gamma}$, but it is still increasing with $\kappa$. This behavior of the current is related to the population of purely electronic states and depopulation of photon replica states.
The integration of a single III-V semiconductor quantum dot with a plasmonic nanoantenna as a means toward efficient single-photon sources (SPEs) is limited due to its weak, wide-angle emission, and low emission rate. These limitations can be overcome by designing a unique linear array of plasmonic antenna structures coupled to nanowire-based quantum dot (NWQD) emitters. A linear array of a coupled device composed of multiple plasmonic antennas at an optimum distance from the quantum dot emitter can be designed to enhance the directionality and the spontaneous emission rate of an integrated single-photon emitter. Finite element modeling has been used to design these compact structures with high quantum efficiencies and directionality of single-photon emission while retaining the advantages of NWQDs. The Purcell enhancement factor of these structures approaches 66.1 and 145.8, respectively. Compared to a single NWQD of the same diameter, the fluorescence was enhanced by 1054 and 2916 times. The predicted collection efficiencies approach 85% (numerical aperture, NA = 0.5 ) and 80% ( NA = 0.5 ), respectively. Unlike single-photon emitters based on bulky conventional optics, this is a unique nanophotonic single-emission photon source based on a line-array configuration that uses a surface plasmon-enhanced design with minimum dissipation. The designs presented in this work will facilitate the development of SPEs with potential integration with semiconductor optoelectronics.
We study electron transport properties through a double quantum dot (DQD) system coupled to a single mode photon cavity, DQD-cavity. The DQD system has a complex multilevel energy spectrum, in which by tuning the photon energy several anti-crossings between the electron states of the DQD system and photon dressed states are produced, which have not been seen in a simple two level DQD system. Three different regions of the photon energy are studied based on anti-crossings, where the photon energy ranges are classified as “low”, “intermediate”, and “high”. The anti-crossings represent multiple Rabi-resonances, which lead to a current dip in the electron transport at the “intermediate” photon energy. Increasing the electron-photon coupling strength, gγ, the photon exchanges between the anti-crossing states are changed leading to a dislocation of the multiple Rabi resonance states. Consequently, the current dip at the intermediate photon energy is further reduced. Additionally, we tune the cavity-environment coupling, κ, to see how the transport properties in the strong coupling regime, gγ>κ, are changed for different directions of the photon polarization. Increasing κ with a constant value of gγ, a current enhancement in the intermediate photon energy is found, and a reduction in the current is seen for the “high” photon energy range. The current enhancement in the intermediate photon energy is caused by the weakening of the multiple Rabi-resonance in the system.
Electronic confined states of a cylindrical InP quantum dot embedded in infinite GaP nanowire is studied theoretically. To this end the Schrodinger equation is solved numerically in the effective mass approximation. The subband separation between the GaP nanowire and InP/GaP core–shell nanowire is utilized to predict the possible existence of the three dimensionally confined states of the system. Using this, the nanowire critical radius is calculated for each channel of angular momentum, the frontier of type I-Type II transition in the InP/GaP quantum dot nanowire system. It is shown that the lower limit of the continuum energy depends on the angular momentum and increases by it, causing discrete bound states of higher angular momentum to lie in the continuum of the lower ones. Surviving the energy states in the presence of external magnetic field reveals stronger confinement for electrons in states with negative angular momentum quantum numbers.
Two-dimensional photonic crystal nanocavities were designed to tailor cavity quantum electrodynamics. Enhancing the spontaneous emission of low-quality factor nanocavity with embedded CdSe quantum dots (QDs) emitters is the aim of this study. Low concentration layer of CdSe QDs was sandwiched between two layers of Si2 N3 membrane using plasma-enhanced chemical vapor deposition. The modification rate in spontaneous emission of L3 nanocavity up to 2.3-fold has been observed at 629.5 nm in compare to bare cavities. High field confinement in the sub-wavelength regime became an interest field for quantum electrodynamics applications and good platform to study light matter interactions.
