Departmental Seminar

Spectrally-uniform quantum dot single photon emitter arrays integrable on-chip with multifunctional dielectric light manipulation units: A new paradigm for scalable quantum optical circuits

Professor Anupam Madhukar
University of Southern California

Scalable quantum optical circuits aimed at quantum information processing require, at their core, spatially ordered arrays of spectrally uniform single photon emitters that are on-chip integrable with co-designed multifunctional units (metastructures) needed to manipulate the emitted photons. Towards this objective, a bottleneck has been the lack of single photon source (single quantum dot or color center) arrays that meet these requirements.

This talk will thus focus first on an approach to synthesizing a class of spatially ordered arrays of semiconductor single quantum dots (SQDs) that are in precise spatial locations and exhibit remarkable as-grown emission wavelength uniformity (compared to the commonly employed 3D island based self-assembled quantum dots). This class of SQDs, dubbed mesa-top single quantum dots (MTSQDs), we show are efficient single photon sources (SPS) with a few pairs in an as-grown 5X8 array emitting within 300 μeV.

The single photon emission purity is~ 98.9% at ~10K and ~80% at the elevated temperature of ~77K. These MTSQD arrays thus show considerable promise for enabling controlled interference between photons generated, on-demand, from known distinct sources.

The talk will thus next address the scalable on-chip integration of SPS arrays (such as MTSQDs) with emitted light manipulating units (LMUs) that need to provide five functions: emission rate enhancement (Purcell effect), directed emission (nanoantenna effect), state-preserving guided propagation of the emitted photons, efficient beam splitting, and beam-combining with controlled phase matching.

For these five tasks, we have proposed a new paradigm of realizing LMUs that exploits a single collective Mie resonance of co-designed metastructures of interacting sub-wavelength sized high index dielectric building blocks (DBBs). Such LMUs have significantly smaller on-chip foot print compared to the traditional approach of 2D photonic crystal platform that relies upon departures from Bragg diffraction to generate the needed spatially-localized functions. Simulations of the performance of such Mie resonance based all-dielectric metastructures will be presented. The findings point to the potential of SPS-DBB LMU based small footprint scalable optical circuits capable of working at the single photon limit.

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