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Seminars»11.10.2018 - Vasilios Karanikolas : Quantum Optics with 2D Material Nanostructures

11.10.2018 - Vasilios Karanikolas : Quantum Optics with 2D Material Nanostructures

Quantum Optics with 2D Material Nanostructures

Vasilios Karanikolas
Materials Science Department, University of Patras, Patras, Achaia, Greece
11 October 2018, Thursday, 14:40
Cavid Erginsoy Seminar Room, Physics Department, 3rd floor

Abstract: The manipulation of the spontaneous emission (SE) rate of a quantum emitter (QE) interacting with nanostructures is important for a vast amount of applications, like sensing, light harvesting and emitting devices. Usualy noble metal (Au,Ag) nanostructures are considered, where the SE rate can be enhanced several orders of magnitude by exciting the surface plasmon modes. These modes are confined in the interface between the metal and the dielectric material. The noble metals are lossy materials, thus limit their efficient usage in applications.

A new family of two-dimensional materials, the transition metal dichalcogenides (TMDs), which are direct band-gap semiconductors, with high absorption and intense photoluminescence, are a new canditate for substituting noble metals. We focus on the MoS 2 material parameters and start by classifying the allowed TE and TM exciton polariton modes. Experimental results regarding the SE rate of QE in the vicinity of MoS 2 superlattices are explained using our theoretical model.

Next, we introduce a MoS 2 nanodisk as the environment of the QE and envision a LED application. We present how the MoS 2 nanodisk supports localized exciton modes and we categorize them using the TM modes of an infinite MoS 2 layer. At specific resonance modes we present a high quantum efficiency device. Moving the QE closer to the MoS 2 nanodisk, we observe an emission spectrum that can only be explained by using the strong coupling regime description.

The SE rate of the QE in the presence of the above nanostructures is calculated in the context of non-Hermitian description of QED. The SE rate is a quantity that is defined in the weak coupling regime. For the strong coupling regime, we employ a non-Markovian description of the light-matter interaction.