Giant nonlinear interaction between two optical beams via a quantum dot embedded in a photonic wire

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Giant nonlinear interaction between two optical beams via a quantum dot embedded in a photonic wire

H. A. Nguyen, T. Grange, B. Reznychenko, I. Yeo, P.-L. de Assis, D. Tumanov, F. Fratini, N. S. Malik, E. Dupuy, N. Gregersen, A. Auffèves, J.-M. Gérard, J. Claudon, and J.-Ph. Poizat

Phys. Rev. B 97, 201106(R) – Published 11 May 2018

Abstract

Optical nonlinearities usually appear for large intensities, but discrete transitions allow for giant nonlinearities operating at the single-photon level. This has been demonstrated in the last decade for a single optical mode with cold atomic gases, or single two-level systems coupled to light via a tailored photonic environment. Here, we demonstrate a two-mode giant nonlinearity with a single semiconductor quantum dot (QD) embedded in a photonic wire antenna. We exploit two detuned optical transitions associated with the exciton-biexciton QD level scheme. Owing to the broadband waveguide antenna, the two transitions are efficiently interfaced with two free-space laser beams. The reflection of one laser beam is then controlled by the other beam, with a threshold power as low as 10 photons per exciton lifetime ( $1.6 nW$ ). Such a two-color nonlinearity opens appealing perspectives for the realization of ultralow-power logical gates and optical quantum gates, and could also be implemented in an integrated photonic circuit based on planar waveguides.

Received 18 June 2017
Revised 23 April 2018

DOI:https://doi.org/10.1103/PhysRevB.97.201106

Physics Subject Headings (PhySH)

Nanoantennas Nonlinear optics Photonics Quantum optics Quantum optics with artificial atoms Semiconductor quantum optics

Quantum dots

Atomic, Molecular & Optical

Authors & Affiliations

H. A. Nguyen¹, T. Grange¹, B. Reznychenko¹, I. Yeo^1,2, P.-L. de Assis³, D. Tumanov¹, F. Fratini¹, N. S. Malik², E. Dupuy², N. Gregersen⁴, A. Auffèves¹, J.-M. Gérard², J. Claudon², and J.-Ph. Poizat^1,*

¹Université Grenoble Alpes, CNRS, Grenoble INP, Institut NEEL, “Nanophysique et Semiconducteurs” group, F-38000 Grenoble, France
²Université Grenoble Alpes, CEA, INAC, PHELIQS, “Nanophysique et Semiconducteurs” group, F-38000 Grenoble, France
³Gleb Wataghin Institute of Physics, University of Campinas - UNICAMP, 13083-859, Campinas, São Paulo, Brazil
⁴Department of Photonics Engineering, DTU Fotonik, Kongens Lyngby, Denmark

^*Corresponding author: jean-philippe.poizat@neel.cnrs.fr

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Issue

Vol. 97, Iss. 20 — 15 May 2018

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Images

Figure 1
Sample and setup. (a) A scanning electron microscope image of the photonic wire antenna is shown on the right. The center part details the location of the QD at the bottom of the wire. The waveguide, with a local diameter of 500 nm, ensures an efficient coupling of the QD spontaneous emission to the fundamental guided mode. The empty QD (0), the excitonic ( $X_{y}$ ), and biexcitonic ( $X X$ ) states form a nondegenerate three-level ladder scheme as represented on the left. The two transitions are addressed by two different lasers. (b) Experimental setup. Two tunable continuous-wave lasers excite the QD transitions. The lasers are spatially filtered with a pinhole located at the focal point of a lens and focused on the device with a microscope objective. A confocal detection with a pinhole selects only the light coming out of the photonic wire. An extra nonresonant (NR) laser is used for photoluminescence spectroscopy, and as a “quietening laser” during the experiments [30, 31]. A polarizing beam splitter (PBS) is used for a cross-polarized detection scheme. (c) The lasers are linearly polarized at an angle $α あるふぁ = 27^{\circ}$ with respect to the QD dipoles of interest. The detection is performed along the polarization orthogonal to the laser polarization. Wave plates in front of the objective ensure a precise control of the laser polarization [32].
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Figure 2
Population switch. The control (probe) laser is tuned around the lower (upper) transition. (a) When the control laser is off, the probe laser beam sees empty levels and is transmitted. (b) When the control laser is on, the excitonic state is populated so that the probe laser beam is reflected. (c) Probe reflectivity as a function of the control laser power, for a probe laser power of $0.5 nW$ (solid squares) and of $2.6 nW$ (open circles). This corresponds respectively to 0.1 and 0.5 of the saturation power. The solid and dashed lines are fits using our theoretical model with parameters that have also been used for the fitting of the data presented in Fig. 3.
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Figure 3
Switch in the Autler-Townes configuration. The control (probe) laser is tuned on the upper (lower) transition. (a) When the control laser is off, the probe is reflected. (b) When the control laser is on, it splits the $X_{y}$ state, so that the probe is no longer on resonance, and therefore transmitted. (c) Probe reflectivity as a function of its detuning for different control laser powers, and a zero control laser detuning. The solid lines are fits using an individual line profile with the line position as a free parameter. The thinner line is the sum of the individual lines. We have checked that the splitting scales as the square root of the control laser power (data not shown). (d) Probe reflectivity as a function of the control laser power. The probe laser power is $1 nW$ . The solid line is the result given by our theoretical model. (e) Position of the Autler-Townes doublet as the control laser is scanned across the upper transition. (f) Experimental [30] and (g) theoretical reflectivity of the probe laser beam as a function of probe and control laser detunings. The probe (control) laser power is $1 nW$ ( $274 nW$ ). The theoretical fits are all made with the same set of parameters as in Fig. 2.
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