Seminarium Fizyki Ciała Stałego

Harvesting and control of the coherence generated by single emitters in solids is a prerequisite for their use in future optical information technologies. Over the last decade, four-wave mixing micro-spectroscopy (FWM) [1] has emerged as a successful approach to access coherence dynamics of excitons confined in individual quantum dots (QDs). The challenge of this experiment lies in distinguishing a weak response of a QD exciton from the resonant excitation background, dominating the signal typically by ten orders of magnitude in the intensity. Recently, we have demonstrated that using suitable nanophotonic devices [1,2,3,4,5] one can amplify the field around the QD, enhancing generation of the excitonic FWM signals, and drastically reducing the resonant background. I will show how this strategy has helped us to progress in the investigations of optical coherence of individual excitons, by accessing the FWM dynamics with a high signal-to-noise ratio. I will then focus on my current efforts to achieve the long-range radiative coupling within a pair of QDs, by exploiting propagative coherence in deterministically defined photonic waveguides. As an outlook, I will highlight ideas, which now emerge from combining coherent nonlinear nanophotonics with optomechanics and two-dimensional materials [6,7].
[1] F. Fras et al. “Multi-wave coherent control of a solid-state single emitter” Nat. Photon. 10, 155 (2016)
[2] J. Kasprzak et al. “Up on the Jaynes-Cummings ladder of a quantum dot-microcavity system” Nat. Mater. 9, 304 (2010)
[3] W. Pacuski et al. “Antireflective photonic structure for coherent nonlinear spectroscopy of single magneticquantum dots” Crys. Growth & Design (2017)
[4] Q. Mermillod et al. “Harvesting, Coupling, and Control of Single-Exciton Coherences in Photonic WaveguideAntennas” Phys. Rev. Lett. 116, 163903 (2016)
[5] T. Jakubczyk et al. “Impact of phonons on dephasing of individual excitons in deterministic quantum dot microlenses” ACS Photon. 3, 2461 (2016)
[6] T. Jakubczyk et al. “Radiatively Limited Dephasing and Exciton Dynamics in MoSe2 Monolayers Revealed withFour-Wave Mixing Microscopy” Nano Lett. 16, 5333 (2016)
[7] T. Jakubczyk et al. “Impact of environment on dynamics of exciton complexes in a WS2 monolayer” 2D Materials, 10.1088/2053-1583/aabc1c, (2018)