arXiv subjects

J. Guimbao

Publications and source records attributed to J. Guimbao.

3 recordsLinked to original sources

arXiv2022

Perfect photon indistinguishability from a set of dissipative quantum emitters

Single photon sources (SPS) based on semiconductor quantum dot (QD) platforms are restricted to low temperature (T) operation due to the presence of strong dephasing processes. Despite the integration of QD in optical cavities provides an enhancement of its emission properties, the technical requirements for maintaining high indistinguishability (I) at high T are beyond the state of the art. Recently, new theoretical approaches have shown promising results by implementing two-dipole-coupled-emitter systems. Here, we have developed a theory to estimate I in a two-emitter system with strong dephasing coupled to a photonic cavity. We have obtained an analytical expression for I that predicts the cavity restrictions depending on the distance between the emitters. Furthermore, we develop an alternative interpretation of I which provide insigths for systems with a larger number of emitters. We find the optimal configuration for maximum I in the case of a five-emitter system using a machine-learning optimization procedure which models the Lindblad equation and provides the optimal position of each emitter to maximize I. The optimized configuration provides perfect I while relaxes the cavity requirements to more experimentally accessible values.

quant-ph↗

arXiv2022

Numerical optimization of a nanophotonic cavity by machine learning for near-unity photon indistinguishability at room temperature

Room-temperature (RT), on-chip deterministic generation of indistinguishable photons coupled to photonic integrated circuits is key for quantum photonic applications. Nevertheless, high indistinguishability (I) at RT is difficult to obtain due to the intrinsic dephasing of most deterministic single-photon sources (SPS). Here we present a numerical demonstration of the design and optimization of a hybrid slot-Bragg nanophotonic cavity that achieves theoretical near-unity I and high coupling efficiency (\b{eta}) at RT for a variety of singlephoton emitters. Our numerical simulations predict modal volumes in the order of 10-3 (λ/2n)3 , allowing for strong coupling of quantum photonic emitters that can be heterogeneously integrated. We show that high I and \b{eta} should be possible by fine-tuning the quality factor (Q) depending on the intrinsic properties of the single-photon emitter. Furthermore, we perform a machine learning optimization based on the combination of a deep neural network and a genetic algorithm (GA) to further decrease the modal volume by almost three times while relaxing the tight dimensions of the slot width required for strong coupling. The optimized device has a slot width of 20 nm. The design requires fabrication resolution in the limit of the current state-ofthe-art technology. Also, the condition for high I and \b{eta} requires a positioning accuracy of the quantum emitter at the nanometer level. Although the proposal is not a scalable technology, it can be suitable for experimental demonstration of single photon operation

quant-ph↗

arXiv2021

Enhancement of the indistinguishability of single photon emitters coupled to photonic waveguides

One of the main steps towards large-scale quantum photonics consists of the integration of single photon sources (SPS) with photonic integrated circuits (PICs). For that purpose, the PICs should offer an efficient light coupling and a high preservation of the indistinguishability of photons. Therefore, optimization of the indistinguishability through waveguide design is especially relevant. In this work we have developed an analytical model to calculate the coupling and the indistinguishability of an ideal point-source quantum emitter coupled to a photonic waveguide depending on source orientation and position. The model has been numerically evaluated through finite-difference time-domain (FDTD) simulations showing consistent results. The maximum coupling is achieved when the emitter is embedded in the center of the waveguide but somewhat surprisingly the maximum indistinguishability appears when the emitter is placed at the edge of the waveguide where the electric field is stronger due to the surface discontinuity.

physics.app-ph↗