arXiv subjects

Martin Arentoft Jacobsen

Publications and source records attributed to Martin Arentoft Jacobsen.

6 recordsLinked to original sources

arXiv2026

Enhancing the efficiency of quantum-dot-based single-photon source designs by suppressing background emission using concentric rings

In this paper, we theoretically demonstrate that a few-period circular Bragg reflector consisting of concentric rings placed around an infinite nanowire with an embedded quantum dot can increase the fraction of radiative emission into the fundamental $\mathrm{HE}_{11}$ mode ($β=Γ_{\rm HE_{11}}/Γ_{\rm Total}$) up to 0.999 due to enhanced suppression of the emission into radiation modes caused by a photonic bandgap effect. We then apply this strategy in the practically relevant case of the finite-sized single-photon source based on tapered nanowires and demonstrate that the collection efficiency can be improved. Additionally, we also show the beneficial effects of placing optimized rings around the micropillar single-photon source.

physics.optics↗

arXiv2025

Deterministic fabrication of GaAs-quantum-dot micropillar single-photon sources

This study investigates the performance of droplet-etched GaAs quantum dots (QDs) integrated into micropillar structures using a deterministic fabrication technique. We demonstrate a unity QD positioning yield across 74 devices and consistent device performance. Under p-shell excitation, the QD decay dynamics within the micropillars exhibit biexponential behavior, accompanied by intensity fluctuations limiting the source efficiency to < 4.5%. Charge stabilization via low-power above-band LED excitation effectively reduces these fluctuations, doubling the source efficiency to $\sim$ 9%. Moreover, we introduce suppression of radiation modes by introducing cylindrical rings theoretically predicted to boost the collection efficiency by a factor of 4. Experimentally, only a modest improvement is obtained, underscoring the influence of even minor fabrication imperfections for this advanced design. Our findings demonstrate the reliability of our deterministic fabrication approach in producing high-yield, uniform devices, while offering detailed insights into the influence of charge noise and complex relaxation dynamics on the performance.

physics.optics↗

arXiv2024

Assessing the alignment accuracy of state-of-the-art deterministic fabrication methods for single quantum dot devices

The realization of efficient quantum light sources relies on the integration of self-assembled quantum dots (QDs) into photonic nanostructures with high spatial positioning accuracy. In this work, we present a comprehensive investigation of the QD position accuracy, obtained using two marker-based QD positioning techniques, photoluminescence (PL) and cathodoluminescence (CL) imaging, as well as using a marker-free in-situ electron beam lithography (in-situ EBL) technique. We employ four PL imaging configurations with three different image processing approaches and compare them with CL imaging. We fabricate circular mesa structures based on the obtained QD coordinates from both PL and CL image processing to evaluate the final positioning accuracy. This yields final position offset of the QD relative to the mesa center of $μ_x$ = (-40$\pm$58) nm and $μ_y$ = (-39$\pm$85) nm with PL imaging and $μ_x$ = (-39$\pm$30) nm and $μ_y$ = (25$\pm$77) nm with CL imaging, which are comparable to the offset $μ_x$ = (20$\pm$40) nm and $μ_y$ = (-14$\pm$39) nm obtained using the in-situ EBL method. We discuss the possible causes of the observed offsets, which are significantly larger than the QD localization uncertainty obtained from simply imaging the QD light emission from an unstructured wafer. Our study highlights the influences of the image processing technique and the subsequent fabrication process on the final positioning accuracy for a QD placed inside a photonic nanostructure.

physics.optics↗

arXiv2023

Performance of the nanopost single-photon source: beyond the single-mode model

We present a detailed analysis of the physics governing the collection efficiency and the Purcell enhancement of the nanopost single-photon source. We show that a standard single-mode Fabry-Pérot model is insufficient to describe the device performance, which benefits significantly from scattering from the fundamental mode to radiation modes. We show how the scattering mechanism decouples the collection efficiency from the Purcell enhancement, such that maximum collection efficiency is obtained off-resonance. Finally, we discuss how this scattering mechanism can be beneficial for future single-photon source designs.

quant-ph↗

arXiv2022

Near-unity efficiency and photon indistinguishability for the "hourglass" single-photon source using suppression of background emission

An on-going challenge within scalable optical quantum information processing is to increase the collection efficiency $\varepsilon$ and the photon indistinguishability $η$ of the single-photon source towards unity. Within quantum dot-based sources, the prospect of increasing the product $\varepsilon η$ arbitrarily close to unity was recently questioned. In this work, we discuss the influence of the trade-off between efficiency and indistinguishability in the presence of phonon-induced decoherence, and we show that the photonic "hourglass" design allows for improving $\varepsilon η$ beyond the predicted maximum for the standard micropillar design subject to this trade-off. This circumvention of the trade-off is possible thanks to control of the spontaneous emission into background radiation modes, and our work highlights the importance of engineering of the background emission in future pursuits of near-unity performance of quantum dot single-photon sources.

quant-ph↗

arXiv2020

Technological implementation of a photonic Bier-Glass cavity

In this paper, we introduce a novel quantum photonic device, which we term photonic Bier-Glass cavity. We discuss its fabrication and functionality, which is based on the coupling of integrated In(Ga)As quantum dots to a broadband photonic cavity resonance. By design, the device architecture uniquely combines the Purcell enhancement of a photonic micropillar structure with broadband photonic mode shaping of a vertical, tapered waveguide, making it an interesting candidate to enable the efficient extraction of entangled photon pairs. We detail the epitaxial growth of the heterostructure and the necessary lithography steps to approach a GaAs-based photonic device with a height exceeding 15 $μ$m, supported on a pedestal that can be as thin as 20 nm. We present an optical characterization, which confirms the presence of broadband optical resonances, in conjunction with amplified spontaneous emission of single photons.

physics.app-ph↗