We report on the resonance fluorescence (RF) from single InAs quantum dots (QDs) emitting at the telecom band of 1300 nm. The InAs/GaAs QDs are embedded in a planar optical microcavity and the RF is measured by an orthogonal excitation-detection geometry for deeply suppressing the residual laser scattering. An ultra-weak He–Ne laser is necessary to be used as a gate laser for obtaining RF. Rabi oscillation with more than one period is observed through the picosecond (ps) pulsed laser excitation. The resonant control of exciton opens up new possibilities for realizing the on-demand single photon emission and quantum manipulation of solid-state qubits at telecom band.
We report on the resonance fluorescence (RF) from single InAs quantum dots (QDs) emitting at the telecom band of 1300 nm. The InAs/GaAs QDs are embedded in a planar optical microcavity and the RF is measured by an orthogonal excitation-detection geometry for deeply suppressing the residual laser scattering. An ultra-weak He–Ne laser is necessary to be used as a gate laser for obtaining RF. Rabi oscillation with more than one period is observed through the picosecond (ps) pulsed laser excitation. The resonant control of exciton opens up new possibilities for realizing the on-demand single photon emission and quantum manipulation of solid-state qubits at telecom band.
We report on coherent resonant emission of the fundamental exciton state in a single semiconductor GaAs quantum dot. A resonant regime with picosecond laser excitation is realized by embedding the quantum dots in a one-dimensional waveguiding structure. As the pulse intensity is increased, Rabi oscillation is observed up to three periods. The Rabi regime is achieved owing to an enhanced light-matter coupling in the waveguide but with different dynamics with respect to usual cavity quantum electrodynamics. The resonant control of the quantum dot fundamental transition opens new possibilities in quantum state manipulation and quantum optics experiments in condensed-matter physics.
Single photon emission is one of the most striking optical properties of semiconductor quantum dots (QDs), and the corresponding photon anti-bunching effect was observed by photoluminescence experiments in single QDs under non-resonant excitation [1]. In this configuration, the residual excitation of the QD environment that acts as a fluctuating reservoir for spectral diffusion [2] reduces the coherence time and prevents from the realization of single photons sources with high degree of indistinguishability. Therefore, strictly resonant excitation of the fundamental interband transition [3,4,5] is essential to reduce the dephasing processes and get high-performance single photon sources. In this paper, we report on the resonant Rayleigh scattering (RRS) of the exciton in single InAs/GaAs QDs embedded in a planar microcavity [3]. Strikingly, the most frequent case (98%) corresponds to the absence of resonance in the RRS spectrum, resulting in QDs non-coupled to light. We show that resonant fluorescence of the exciton is restored for all the QDs when an additional non-resonant laser is applied at extremely weak power ranges (few nWs). A clear photon anti-bunching under strictly resonant excitation proves that the optically gated RRS spectrum is dominated by resonant fluorescence of the exciton. A complete study will be presented such as the switching dynamics of the RRS and its power dependence with the resonant and non-resonant lasers. The phenomenon is interpreted within a simple model where the exciton resonant fluorescence is quenched by Coulomb blockade after tunneling of a hole in the QD from a structural deep level. The additional non-resonant laser suppresses Coulomb blockade by switching back the QD into a neutral state. We conclude that the optical response of the QD remains affected by its environment even in case of coherent resonant pumping. An optical control of the QD environment is essential to bring the QD from a "dark" to a "bright" state under strictly resonant excitation. References [1] P. Michler et al., Science 290, 2282 (2000) [2] A. Berthelot et al., Nature Physics 2, 759 (2006) [3] A. Muller et al., PRL 99, 187402 (2007) [4] R. Melet et al., PRB 78, 073301 (2008) [5] S. Ates et al., PRL 103, 167402 (2009)
Single photon emission is one of the most striking optical properties of semiconductor quantum dots (QDs), and the corresponding photon anti-bunching effect was observed by non-resonant and resonant photoluminescence experiments in single QDs [1,2,3,4]. Other experiments demonstrated the possibility to use single QDs for the generation of indistinguishable single photons [3]. An important general issue is to reach the so-called fundamental radiative limit. Several strategies have been followed in that sense such as the shortening of population lifetime induced by the Purcell effect [5] or the reduction of pure dephasing by resonant excitation [2,3,4]. Up to now, all the measurements reported in the literature focus on the incoherent photoluminescence signal for achieving single photon emission. In this regime, the linewidth of the photoluminescence spectrum is always limited to the radiative limit. In this paper, we report on the resonant emission (RE) of the exciton in single InAs/GaAs QDs embedded in a planar microcavity, in an orthogonal excitation-detection geometry [4]. We present an original type of single photon source based on the coherent laser light scattering by a single QD [6]. Besides the antibunching effect showing the non-classical nature of the emitted light, we observe that the QD emission spectrum is determined by the spectrum of the resonant excitation laser. We present high-resolution measurements by Fourier transform spectroscopy of the RE where the data are fitted to the first-order correlation function g(1)(τ) of the RE of a two-level system. The inverse Fourier transform of the g(1)(τ) function allows a direct comparison of the different RE emission profiles. We show that, by reducing the resonant excitation power, the so-called Mollow triplet shrinks to a single narrow Lorentzian line, while the relative intensity of this narrow peak increases and tends to overwhelm the RE spectrum. This implies that single QDs can produce single photons with a coherence time that is not limited anymore by the QD electronic properties, resulting in an ultra-coherent character [6]. In conclusion, the resulting " ultra-coherent single photon source " promises high degrees of indistinguishability of the emitted photons which is a crucial requirement for quantum information applications. [1] P. Michler et al., Science 290, 2282 (2000). [2] A. Muller et al., Phys. Rev. Lett. 99, 187402 (2007). [3] S. Ates et al., Phys. Rev. Lett. 103, 167402 (2009). [4] H. S. Nguyen et al., Phys. Rev. Lett. 108, 057401 (2012). [5] C. Santori et al., Nature 419, 594 (2002). [6] H. S. Nguyen et al., Appl. Phys. Lett. 99, 261904 (2011).
An emission wavelength around 1550 nm (telecom C-band) is highly appealing for nonclassical light sources, among others, due to the absorption minimum in standard glass fibers. In particular, semiconductor quantum dots at this wavelength promise to provide the outstanding results achieved with this emitter type in the near-infrared spectral region. Here, we study resonance fluorescence from InAs/GaAs quantum dots emitting in the telecom C-band under continuous wave and pulsed excitation. For the prior case, the quantum dot is excited in the strong driving regime and the characteristic Mollow triplet is observed allowing to draw conclusions on the nature and quantitative influence of different decoherence mechanisms on the emission. Furthermore, under pulsed excitation, highly pure single-photon emission (g(2)(0)=0.023 ± 0.019) is demonstrated and a measurement of the photon indistinguishability (VTPI=0.144 ± 0.015; full width at half maximum of the time window for post-selection of (305 ± 33)ps with an associated maximally attainable value VTPI,p=0.955) is presented. In the process of making the emission properties of telecom quantum dots comparable to their well-established counterparts emitting in the near-infrared spectral region, these results represent a benchmark and provide valuable information for future optimization of sample structures.
Semiconductor nanostructures such as quantum dots (QDs) have offered unique opportunities to investigate quantum optical effects in solid-state systems. These include quantum interference, Rabi oscillations, as well as photon antibunching, and were previously observable only in isolated atoms or ions. In addition, QDs can be integrated into optical microcavities, making them attractive for applications in quantum information processing and high efficiency quantum light sources. Despite much progress towards these goals, one area that was little explored is coherent control of such solid-state quantum emitters in cavities. The main technical hurdle lies in overcoming the laser background scattering. By using a sample structure in which QDs are embedded in a planar Fabry-Perot cavity and by using an orthogonal excitation geometry, we have achieved a nearly complete elimination of laser background scattering. This in turn allows us to show resonantly controlled light emission of quantum dots in the cavity including (a) Rabi flopping using pulse control, (b) direct observation of Mollow triplets in the frequency domain, and (c) simultaneously measured first-order and second order photon-photon correlations.