Tunable Photon Statistics Exploiting the Fano Effect in a Waveguide

Abstract

A strong optical nonlinearity arises when coherent light is scattered by a semiconductor quantum dot (QD) coupled to a nano-photonic waveguide. We exploit the Fano effect in such a waveguide to control the phase of the quantum interference underpinning the nonlinearity, experimentally demonstrating a tunable quantum optical filter which converts a coherent input state into either a bunched, or antibunched non-classical output state. We show theoretically that the generation of non-classical light is predicated on the formation of a two-photon bound state due to the interaction of the input coherent state with the QD. Our model demonstrates that the tunable photon statistics arise from the dependence of the sign of two-photon interference (either constructive or destructive) on the detuning of the input relative to the Fano resonance.

Experimental Reconstruction of the Few-Photon Nonlinear Scattering Matrix from a Single Quantum Dot in a Nanophotonic Waveguide

“…To do so, we additionally measure the transmission intensities I t ðωÞ at various excitation powers, as well as photon correlations in all directions g ð2Þ tt , g ð2Þ rr , and g ð2Þ tr . By modeling this entire dataset using a least squares fit, we arrive at a descriptive parameter set of β ¼ 0.87½0.83; 0.91 and dephasing rate γ d ≃ 0½0; 0.02γ tot , consistent with results from the literature [17,23]. In the analysis, we also include the finite detector response time, residual spectral diffusion of the QD, background emission stemming from imperfect laser extinction or blinking of the QD state, and minor Fano resonance effects.…”

“…Figure 2(b) shows the second-order correlation function g ð2Þ tt ðτÞ measured in transmission and for the same excitation conditions. It displays a pronounced bunching of g ð2Þ tt ð0Þ ≃ 5, which is significantly higher than in previously reported QD-waveguide experiments [14,16,17] due to the substantial decoherence reduction achieved in our photonemitter interface. The large bunching demonstrates that the incoming Poissonian photon distribution is significantly altered by the interaction with the QD and is the experimental signature of the correlated photon-photon interaction studied in the present Letter.…”

“…It has been a long lasting challenge in quantum optics, and various strategies have been pursued using, e.g., Rydberg blockade interaction in atomic ensembles [4,5] and single emitters in high finesse optical cavities [6,7], as well as superconducting stripline resonators [8][9][10]. Recently, significant progress has been achieved in photonic waveguides, including hollow fibers [11] or nanofibers coupled to atomics ensembles [12], or with single atoms [13] and single solid-state emitters [14][15][16][17][18]. In particular, solid-state quantum dots (QDs) in nanophotonics structures constitute a mature platform where scalable coherent single-photon sources [19,20] have been developed, at the core of the implementation of quantum information processing [21].…”

“…The extinction of transmission on resonance exceeds 85%, a direct testimony of the efficiency and coherence of the photon-emitter interaction. The non-Lorentzian and asymmetric line shape, originates from Fano resonance effects due to weak reflections at the ends of the waveguide [14,17]. Such reflections induce a very low finesse cavity that, depending on the overall intensity normalization (more details in Supplemental Material [51]), can give I t values higher than 1.…”

Coherent characterisation of a single molecule in a photonic black box

“…A third approach, known as extinction spectroscopy, relies on the interference between a continuouswave laser and the resonance fluorescence of the emitter 16,19 . This interference affects the amplitude 20 , phase 21 and photon statistics 22 of the transmitted and reflected fields. Exploration of this phenomenon has led to the demonstration of single emitters as optical transistors 23 , phase switches 24 and quantum memories 25 .…”