Emission spectrum of a quantum dot embedded in a nanocavity

Tarel, Guillaume; Savona, Vincenzo

doi:10.1002/pssc.200880577

Cited by 11 publications

(8 citation statements)

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“…Figure 4(b) shows the autocorrelation histogram of the cavity emission, which indicates g ð2Þ ð0Þ ¼ 0:19ð1Þ. The clear antibunching is markedly different from previous reports which observed weak or no antibunching of the detuned PC cavity mode [2,3], and may be attributed to the expected absence of multiexciton population of the QD under resonant excitation of the single-exciton [25]. A significant contribution to the value of g ð2Þ ð0Þ is due to overlap of the 40-ps pulses with the filter at the cavity frequency, which could be improved by a narrower filter or larger QD-cavity detuning.…”

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confidence: 71%

Resonant Excitation of a Quantum Dot Strongly Coupled to a Photonic Crystal Nanocavity

et al. 2010

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We describe the resonant excitation of a single quantum dot that is strongly coupled to a photonic crystal nanocavity. The cavity represents a spectral window for resonantly probing the optical transitions of the quantum dot. We observe narrow absorption lines attributed to the single and biexcition quantum dot transitions and measure antibunched population of the detuned cavity mode [g ð2Þ ð0Þ ¼ 0:19]. DOI: 10.1103/PhysRevLett.104.073904 PACS numbers: 42.70.Qs, 42.50.Ct, 42.50.Dv, 78.67.Hc Photonic nanocavities coupled to semiconductor quantum dots (QDs) are becoming well developed systems for studying cavity quantum electrodynamics and constructing devices for quantum information processing. Recent experiments have found remarkably strong emission at the cavity resonance even when the QD emission was far detuned [1][2][3][4]. In these experiments the QD was pumped through the wetting layer, which allows for multiexciton processes through the wetting layer or a multi-QD effective continuum. In contrast, in this Letter we investigate the resonant excitation of an InAs quantum dot that is strongly coupled to a photonic crystal cavity. We show that the resonantly excited QD emits efficiently through the cavity mode and model the interaction by a phonon-mediated dephasing model [5][6][7]. In this experiment, the cavity signal effectively becomes a spectrally separated readout channel for high-resolution single quantum dot spectroscopy. In addition, because the QD is resonantly excited, the antibunched cavity emission has the potential for low timing jitter and high photon indistinguishability [7,8].The optical system consists of a photonic crystal (PC) cavity fabricated in a 160-nm thick GaAs membrane which contains a central layer of self-assembled InGaAs QDs. As shown in Fig. 1(c), we employ a grating-integrated cavity (GIC) design [9], based on a linear three-hole defect cavity [10]. The GIC design incorporates a second-order grating around the cavity, as seen in the perturbations in Figs. 1(b) and 1(c), which couple plane waves with low in-plane k vectors with the cavity mode.We first characterize the QD-cavity system by its photoluminescence (PL) under nonresonant excitation at a temperature between 10 and 50 K. A continuous-wave (cw) laser at p ¼ 860 nm excites electron-hole pairs which can relax through a phonon-mediated process into radiative levels of the QD [ Fig. 1(d)]. Figure 1(e) plots the anticrossing between the QD-like and cavitylike states. Fits to the anticrossing spectra yield the system parameters summarized in Fig. 1(d).We measure the reflection of the cavity by the crosspolarized reflectivity method illustrated in Fig. 1(a), as in our earlier work [11]. The cavity is polarized at 45 to the vertical input beam, while the reflection is detected in the horizontal polarization on a charge coupled device (CCD). The table lists the system parameters derived from the measurements, where g, , Ã are the vacuum Rabi frequency, cavity field decay rate, and dipole dephasing rate, respectively. The dip...

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confidence: 71%

Resonant Excitation of a Quantum Dot Strongly Coupled to a Photonic Crystal Nanocavity

et al. 2010

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“…As for cavity-QED, theoretical work has suggested that such pure phonon dephasing might be responsible for cavity feeding at detunings of the order of the polariton linewidths. 25,26,27,28,29 Experimental work has confirmed that for such small detunings dephasing plays a crucial role.…”

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Cavity quantum electrodynamics with semiconductor quantum dots: Role of phonon-assisted cavity feeding

2010

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For a semiconductor quantum dot strongly coupled to a microcavity, we theoretically investigate phonon-assisted transitions from the exciton to a cavity photon, where the energy mismatch is compensated by phonon emission or absorption. By means of a Schrieffer-Wolff transformation we derive an effective Hamiltonian, which describes the combined effect of exciton-cavity and excitonphonon coupling, and compute the scattering rates within a Fermi golden rule approach. The results of this approach are compared with those of a recently reported description scheme based on the independent Boson model [U. Hohenester et al., Phys. Rev. B 80, 201311(R) (2009)], and a numerical density matrix approach. All description schemes are shown to give very similar results. We present results for the spontaneous emission lifetime of a quantum dot initially populated with a single exciton or biexciton, and for the spectral properties of an optically driven dot-cavity system operating in the strong coupling regime. Our results demonstrate that phonon-assisted feeding plays a dominant role for strongly coupled dot-cavity systems, when the detuning is of the order of a few millielectron volts.

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“…This behaviour is indicative of a complex light-matter interaction in a semiconductor well beyond the widely used two-level emitter-cavity schemes. Different mechanisms such as photon-induced 'shake-up' processes in charged quantum dots [6], dephasing processes [7,8,9] and phonon-mediated processes [10] are currently discussed to understand the experimentally observed features. A well prepared and clearly defined experimental situation is therefore mandatory to gain a thorough understanding of the responsible physical mechanisms behind the non-resonant dot-cavity coupling.Here we present experimental investigations on the non-resonant dot-cavity coupling of a single quantum dot inside a micro-pillar where the dot has been resonantly excited in the s-shell, thereby avoiding the generation of additional charges in the QD and its surrounding.…”

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“…This so-called non-resonantly coupled emission mechanism is not well understood and controversially discussed in the literature: Kaniber et al [6] suggested that the experimentally observed coupling between a single QD and a photonic crystal cavity mode is mediated by photon-induced 'shake-up'-like processes in charged quantum dots. In their theoretical work [7,9], Naesby et al and Auffèves et al demonstrated that dephasing shifts the emission intensity towards the cavity frequency, whereas Tarel and Savona [10] showed the important role of the electron-acoustic-phonon interaction for understanding the emission properties. From the experimental point of view it is desirable to study the coupling mechanism via purely resonant excitation of the QD s-shell in order to obtain a better understanding of the underlying physics.…”

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Non-resonant dot–cavity coupling and its potential for resonant single-quantum-dot spectroscopy

et al. 2009

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1Promising solid-state single-photon sources and cavity quantum electrodynamic schemes have been realized on the basis of coupled quantum dot and micro-/nanocavity systems [1,2]. Recent experimental studies on the single quantum dot (QD) level showed a pronounced emission at the cavity resonance even for strongly detuned dot-cavity systems [3,4,5]. This behaviour is indicative of a complex light-matter interaction in a semiconductor well beyond the widely used two-level emitter-cavity schemes. Different mechanisms such as photon-induced 'shake-up' processes in charged quantum dots [6], dephasing processes [7,8,9] and phonon-mediated processes [10] are currently discussed to understand the experimentally observed features. A well prepared and clearly defined experimental situation is therefore mandatory to gain a thorough understanding of the responsible physical mechanisms behind the non-resonant dot-cavity coupling.Here we present experimental investigations on the non-resonant dot-cavity coupling of a single quantum dot inside a micro-pillar where the dot has been resonantly excited in the s-shell, thereby avoiding the generation of additional charges in the QD and its surrounding. As a direct proof of the pure single dot-cavity system, strong photon anti-bunching is consistently observed in the autocorrelation functions of the QD and the mode emission, as well as in the cross-correlation function between the dot and mode signals. Strong Stokes and anti-Stokes-like emission is observed for energetic QD-mode detunings of up to ∼ 100 times the QD linewidth. Furthermore, we demonstrate that non-resonant dot-cavity coupling can be utilized to directly monitor and study relevant QD s-shell properties like fine-structure splittings, emission saturation and power broadening, as well as photon statistics with negligible background contribu- tions.Our results open a new perspective on the understanding and implementation of dot-cavity systems for single-photon sources, single and multiple quantum dot lasers, semiconductor cavity quantum electrodynamics, and their implementation, e.g. in quantum information technology [11].High Q-factor nano-and micro-cavities can enhance or suppress the spontaneous emission of photons, e.g. from a quantum dot, coupled to a well defined mode by the Purcell effect 2 [12]. For very high-Q (i.e. weakly damped) cavities the spontaneous emission can even become a reversible process so that quantum entanglement of radiation and matter becomes possible, in the so-called strong coupling regime [12]. Resonantly coupled single quantum dot nano-and micro-cavity systems, i.e. with QD and cavity mode in resonance, have been realized both in the weak coupling [1,13] and the strong coupling regime [14,15,16]. Recent experimental results also show significant emission at the cavity resonance even if the single quantum dot is not in resonance with the cavity mode [3,4,5]. Similar observations have also been reported from nano-cavity laser structures with only few QDs as the active medium [17]. This so-ca...

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Emission spectrum of a quantum dot embedded in a nanocavity

Cited by 11 publications

References 9 publications

Resonant Excitation of a Quantum Dot Strongly Coupled to a Photonic Crystal Nanocavity

Resonant Excitation of a Quantum Dot Strongly Coupled to a Photonic Crystal Nanocavity

Cavity quantum electrodynamics with semiconductor quantum dots: Role of phonon-assisted cavity feeding

Non-resonant dot–cavity coupling and its potential for resonant single-quantum-dot spectroscopy

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