Simultaneous anti-bunched and super-bunched photons from a GaAs Quantum dot in a dielectric metasurface
Sanghyeok Park, Oleg Mitrofanov, Kusal M. Abeywickrama, Samuel Prescott, Jaeyeon Yu, Stephanie C Malek, Hyunseung Jung, Emma Renteria, Sadhvikas Addamane, Alisa Javadi, Igal Brener, Prasad P Iyer
cond-mat.mes-hallcond-mat.mtrl-sciphysics.opticsquant-phSubmitted Mar 3, 2026• Announced Mar 4, 2026
Semiconductor quantum dots host a rich manifold of excitonic complexes, including neutral excitons that emit anti-bunched single photons and charged exciton complexes capable of producing super-bunched photons via cascade emission. Accessing both emission regimes from a single emitter would open routes to novel quantum protocols, including advanced quantum imaging. In practice, however, emission from charged exciton complexes is intrinsically weak, often orders of magnitude dimmer than neutral excitons, placing simultaneous dual-mode operation out of reach. Here, we overcome this limitation by embedding the quantum dot in a dielectric Mie-resonant metasurface that provides order-of-magnitude photoluminescence enhancement across both neutral and charged exciton transitions of a single GaAs quantum dot. Under identical non-resonant pumping conditions, the emission from the neutral exciton yields anti-bunched emission ($g^{(2)}(0) < 0.5$) and the emission from positively charged exciton complexes shows super-bunched emission ($g^{(2)}(0) > 3.5$) with comparable count rates (~12 kHz). Crucially, super-bunching emerges only when charged exciton emission spectrally overlaps with the Mie resonances and vanishes in un-patterned slabs, demonstrating that photonic engineering, is essential for accessing these weak quantum light states. These results demonstrate a scalable, position-tolerant platform for harnessing the full excitonic structure of solid-state emitters.
Semiconductor quantum dots host a rich manifold of excitonic complexes, including neutral excitons that emit anti-bunched single photons and charged exciton complexes capable of producing super-bunched photons via cascade emission. Accessing both emission regimes from a single emitter would open routes to novel quantum protocols, including advanced quantum imaging. In practice, however, emission from charged exciton complexes is intrinsically weak, often orders of magnitude dimmer than neutral excitons, placing simultaneous dual-mode operation out of reach. Here, we overcome this limitation by embedding the quantum dot in a dielectric Mie-resonant metasurface that provides order-of-magnitude photoluminescence enhancement across both neutral and charged exciton transitions of a single GaAs quantum dot. Under identical non-resonant pumping conditions, the emission from the neutral exciton yields anti-bunched emission (g(2)(0)<0.5) and the emission from positively charged exciton complexes shows super-bunched emission (g(2)(0)>3.5) with comparable count rates (~12 kHz). Crucially, super-bunching emerges only when charged exciton emission spectrally overlaps with the Mie resonances and vanishes in un-patterned slabs, demonstrating that photonic engineering, is essential for accessing these weak quantum light states. These results demonstrate a scalable, position-tolerant platform for harnessing the full excitonic structure of solid-state emitters.
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], and more recently under strictly resonant excitation of the fundamental interband transition [2,3]. This configuration minimizes the residual excitation of the QD environment that acts as a fluctuating reservoir for spectral diffusion [4], and thus allows the generation of indistinguishable photons [3]. In this paper, we report on the resonant fluorescence of the charged exciton of a single InAs/GaAs QD embedded in a planar microcavity [2]. We show in figure 1(a) the photoluminescence spectrum of a single QD with two lines X and CX that are identified as the neutral and charged excitons by auto- and cross-correlation measurements of the g(2) function, in (b,c) and (d) respectively. Fig.2 shows the resonant Rayleigh scattering spectra as a function of the laser detuning with the neutral (a) and charged (b) exciton lines. For X, we fit the spectrum with two Lorentzian lines of width 10¹eV and separated by 12.5¹eV which corresponds to the fine structure splitting. For CX, we observe a line that demonstrates the existence of residual charge carriers even if the laser is tuned in resonance with the lowest excitation of the QD, and its larger width of 40¹eV suggests spectral diffusion dephasing. References [1] P. Michler,A. Kiraz,C. Becher, W. V. Schoenfeld, P. M. Petroff, L. Zhang, E. Hu, and A. Imamoglu, Science 290 2282 (2000). [2] A. Muller, E. B. Flagg, P. Bianucci, X. Y. Wang, D. G. Deppe, W. Ma, J. Zhang, G. J. Salamo, M. Xiao, and C. K. Shih, Phys. Rev. Lett. 99 187402 (2007). [3] S. Ates, S. M. Ulrich, S. Reitzenstein, A. Lffler, A. Forchel, and P. Michler, Phys. Rev. Lett. 103 167402 (2009). [4] A. Berthelot, I. Favero, G. Cassabois, C. Voisin, C. Delalande, Ph. Roussignol, R. Ferreira, and J. M. Grard, Nature Physics 2 759 (2006).
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).
The generation of indistinguishable single photons is a fundamental requirement for photonic quantum technologies. However, spectral fluctuations, often induced by charge noise in epitaxial quantum dots (QDs), lead to exciton dephasing, thereby limiting their practical usage in quantum applications. We present a straightforward approach to mitigate charge noise-induced decoherence in droplet-etched GaAs QDs embedded in an n-i-p diode structure and integrated deterministically into an electrically contacted circular Bragg grating resonator for emission enhancement. The quantum device allows for the stabilization of the charge environment by applying an external electrical field while producing a photon extraction efficiency of (37±2)%. Hong-Ou-Mandel two-photon interference measurements reveal a strong dependence of the exciton dephasing time and interference visibility on the applied bias, in excellent agreement with our theoretical predictions. Notably, the reduction in visibility from a maximum, charge stabilized corrected value of 97% at the optimum bias point follows an inverse square dependence (∝1/I^{2}) with increasing diode current (I) in the forward direction. Under a quasi-resonant excitation scheme, we achieve a maximum exciton dephasing time (T_{2}^{*}) of approximately (6.8±0.5) ns, reaching nearly the Fourier limit (T_{2}=2T_{1}) without the need for complex echo schemes like Ramsey or Carr-Purcell-Meiboom-Gill sequences. These findings are consistent with theoretical predictions from rate equation modeling and quantum optical analysis, as well as voltage-dependent linewidth measurements, demonstrating optimized electrical control of exciton dephasing.
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]. 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 limited to the so-called 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 [2]. We present an original type of single photon source based on the coherent laser light scattering by a single QD [3]. Besides the antibunching effect showing the nonclassical nature of the emitted light, we observe that the QD emission spectrum is determined by the spectrum of the resonant excitation laser. Figure (a,b,c) shows 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 in figure (d,e,f). By reducing the resonant excitation power, the 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 [3]. References [1] P. Michler et al, Science 290, 2282 (2000). [2] H. S. Nguyen et al, Phys. Rev. Lett. (accepted, in press). See arXiv 1109.4304. [3] H. S. Nguyen et al, Appl. Phys. Lett. 99, 261904 (2011).
Resonant laser excitation of a two-level system with subsequent single-photon emission can be used to generate single photons with high indistinguishability or Hong-Ou-Mandel (HOM) visibility. However, spectral overlap between excitation laser and emitted photons generally poses significant challenges. Furthermore, emitter re-excitation intrinsically limits achievable single-photon purity. Established solutions mitigate these issues at significant cost to source efficiency and with increased source complexity. This motivates the use of few-level systems with spectral separation of excitation and emission pathways. One option is a three-level cascade. However, without targeted lifetime engineering of emitting states, the cascade naturally limits achievable photon indistinguishability. Here we study a semiconductor quantum dot with resonant and selective cavity-enhancement of biexciton-to-exciton transition. Following resonant two-photon excitation of the biexciton state, we collect the emitted single photon with the cavity. This approach circumvents emitter re-excitation and naturally introduces spectral separation of excitation laser and emitted single photon. Supported by first experimental results, we demonstrate theoretically that with selective Purcell enhancement, the observed quality quantifiers of single-photon emission (purity, equivalently g(2)(0), and HOM visibility V, equivalently indistinguishability) are competitive with respect to high-quality deterministic quantum-dot single-photon sources. This is already achieved without systematic optimization or targeted system engineering, which firmly places the reported approach as a viable route to the next generation of highest-quality quantum-dot based deterministic single-photon sources.