arXiv subjects

Setthanat Wijitpatima

Publications and source records attributed to Setthanat Wijitpatima.

4 recordsLinked to original sources

arXiv2026

Integrated Whispering-Gallery Microlaser-Waveguide Platform for On-Chip Electrical Excitation of InGaAs Quantum Dots

We report the fabrication and characterization of an integrated quantum photonic device consisting of an electrically driven whispering-gallery-mode micropillar laser evanescently coupled to a ridge waveguide, both incorporating InGaAs quantum dots (QDs). The lasing characteristics of microlasers are systematically investigated as a function of the pillar-waveguide gap distance. Coherent emission from the whispering-gallery-mode microlaser coupled into the waveguide enables on-chip optical excitation of QDs embedded in an electrically contacted micropillar at the end of the waveguide. Under continuous-wave on-chip excitation, we observe single-photon emission with $g^{(2)}(0) = (3.49 \pm 0.01) \%$ for a QD integrated in the outcoupling micropillar which can be spectrally tuned-by the quantum confined Stark effect. These results constitute an important step toward low-footprint, deterministic, and scalable single-photon sources for QD-based integrated quantum photonic circuits.

physics.optics↗

arXiv2026

Strain-Engineered Deterministic Quantum Dots for Telecom O-Band Emission Using Buried Stressors

The deterministic realization of quantum light sources operating at telecom wavelengths is essential for long-distance fiber-based quantum communication and distributed quantum computing. In this work, we demonstrate that telecom O-band emission can be achieved from site-controlled InGaAs/GaAs quantum dots (QDs). Our concept utilizes a buried AlAs/Al$_2$O$_3$ stressor layer with the unique feature that induces a well-defined and controllable tensile strain field at the growth surface, enabling both a redshift of QD emission to the $\sim$1.3~μm range and site-selective nucleation at the mesa centers. This concept eliminates not only the need for strain-reducing layers (SRLs), which are known to degrade optical coherence, but also provides spatial control and spectral tunability. The grown telecom QDs show pure single-photon emission with $g^{(2)}(τ) = (5.0 \pm 1.0) \times 10^{-2}$ at 4 K and $(2.8 \pm 0.3) \times 10^{-1}$ at 77~K, demonstrating the quantum nature and thermal stability of the emitters. The emission characteristics of complex excitonic states are analyzed using 8-band $k \cdot p$ and configuration-interaction modeling, which quantitatively reproduces the experimental observations. Finally, we present a theory-supported strategy to further redshift the emission toward the center of the O-band and beyond by employing a multi-buried-stressor approach. This combined framework of experiment and theory establishes the buried stressor concept as a scalable route toward highly coherent, position-controlled O-band quantum emitters compatible with industrial photonic integration.

cond-mat.mes-hall↗

arXiv2025

Enhancement of Indistinguishable Photon Emission from a GaAs Quantum Dot via Charge Noise Suppression

The generation of indistinguishable single photons is a fundamental requirement for future quantum technologies, particularly in quantum repeater networks and for distributed quantum computing based on entanglement distribution. However, spectral jitter, often induced by charge noise in epitaxial quantum dots, leads to exciton dephasing, thereby limiting their practical usage in quantum applications. We present a straightforward approach to mitigate charge noise-induced decoherence in droplet-etched GaAs quantum dots embedded in an n-i-p diode structure and integrated deterministically into an electrically contacted circular Bragg grating resonator for emission enhancement. The quantum device allows for the stabilization of the charge environment by applying an external electrical field while producing a photon extraction efficiency of approximately (37 +- 2)%. Hong-Ou-Mandel two-photon interference measurements reveal a strong voltage dependence of the exciton dephasing time and interference visibility on the applied bias in excellent agreement with our theoretical predictions. Notably, the reduction in visibility from a maximum, charge-stabilized corrected value of 97 percent at the optimum bias point follows an inverse square dependence (proportional to 1/I^2) with increasing diode current (I) in forward direction. Under a quasi-resonant excitation scheme, we achieve a maximum exciton dephasing time (T2*) of approximately (6.8 +-0.5) ns, reaching nearly the Fourier limit (T2 = 2T1) without the need for complex echo schemes like Ramsey or Carr-Purcell-Meiboom-Gill sequences. These findings are consistent with theoretical predictions from rate equation modeling and quantum optical analysis as well as voltage-dependent linewidth measurements, demonstrating optimized electrical control of exciton dephasing.

cond-mat.mes-hall↗

arXiv2024

Bright electrically contacted circular Bragg grating resonators with deterministically integrated quantum dots

Cavity-enhanced emission of electrically controlled semiconductor quantum dots is essential in developing bright quantum devices for real-world quantum photonic applications. Combining the circular Bragg grating (CBG) approach with a PIN-diode structure, we propose and implement an innovative concept for ridge-based electrically-contacted CBG resonators. Through fine-tuning of device parameters in numerical simulations and deterministic nanoprocessing, we produced electrically controlled single quantum dot CBG resonators with excellent electro-optical emission properties. These include multiple wavelength-tunable emission lines and a photon extraction efficiency (PEE) of up to (30.4$\pm$3.4)%, where refined numerical optimization based on experimental findings suggests a substantial improvement, promising PEE >50%. Additionally, the developed quantum light sources yield single-photon purity reaching (98.8$\pm$0.2)% [post-selected: (99.5$\pm$0.3)%] and a photon indistinguishability of (25.8$\pm$2.1)% [post-selected: (92.8$\pm$4.8)%]. Our results pave the way for high-performance quantum devices with combined cavity enhancement and deterministic charge-environment controls, advancing the development of photonic quantum information systems such as complex quantum repeater networks.

cond-mat.mes-hall↗