A5055631188- Semiconductor Quantum Structures and Devices
- Quantum Information and Cryptography
- Photonic and Optical Devices
- Quantum and electron transport phenomena
- Quantum optics and atomic interactions
- Neural Networks and Reservoir Computing
- Semiconductor Lasers and Optical Devices
- Quantum Dots Synthesis And Properties
- Optical Network Technologies
- Molecular Junctions and Nanostructures
- Quantum Mechanics and Applications
- Quantum Computing Algorithms and Architecture
- Photonic Crystals and Applications
- Semiconductor materials and devices
- Laser Design and Applications
- Surface and Thin Film Phenomena
- Mechanical and Optical Resonators
- Strong Light-Matter Interactions
- Laser-Matter Interactions and Applications
- Data Visualization and Analytics
- Graphene research and applications
- Random lasers and scattering media
- Magneto-Optical Properties and Applications
- Advanced Chemical Physics Studies
- Nanowire Synthesis and Applications
University of Copenhagen
2024-2025
University of Basel
2017-2023
Quantum dots are both excellent single-photon sources and hosts for single spins. This combination enables the deterministic generation of Raman-photons -- bandwidth-matched to an atomic quantum-memory photon cluster states, a resource in quantum communication measurement-based computing. GaAs AlGaAs can be matched frequency rubidium-based memory, have potentially improved electron spin coherence compared widely used InGaAs dots. However, their charge stability optical linewidths typically...
Planar photonic technology provides a highly promising route of creating an on-chip and on-demand source single photons, which can be scaled into circuitry. While self-assembled quantum dots have been proven to excellent coherent single-photon emitters in many microscale structures, nanoscale devices the photon coherence compromised due nearby surfaces. Here, authors achieve 94% indistinguishability photons emitted from waveguide under $p$-shell excitation.
Establishing a highly efficient photon-emitter interface where the intrinsic linewidth broadening is limited solely by spontaneous emission key step in quantum optics. It opens pathway to coherent light-matter interaction for, e.g., generation of indistinguishable photons, few-photon optical nonlinearities, and gates. However, residual mechanisms are ubiquitous need be combated. For solid-state emitters charge nuclear spin noise importance, influence photonic nanostructures on has not been...
We develop an architecture for measurement-based quantum computing using photonic emitters. The exploits spin-photon entanglement as resource states and standard Bell measurements of photons fusing them into a large spin-qubit cluster state. scheme is tailored to emitters with limited memory capabilities since it only uses initial non-adaptive (ballistic) fusion process construct fully percolated graph state multiple By exploring various geometrical constructions entangled from deterministic...
Planar nanophotonic structures enable broadband, near-unity coupling of emission from quantum dots embedded within, thereby realizing ideal single-photon sources. The efficiency and coherence the source is limited by charge noise, which results in broadening spectrum. We report suppression noise fabricating photonic crystal waveguides a gallium arsenide membrane containing p-i-n diode. Local electrical contacts vicinity minimize leakage current allow fast control (≈4 MHz bandwidth) dot...
Solid-state quantum dots are promising candidates for efficient light-matter interfaces connecting internal spin degrees of freedom to the states emitted photons. However, selection rules prevent combination control and optical cyclicity in this platform. By utilizing a photonic crystal waveguide we here experimentally demonstrate up $\approx15$ through state engineering while achieving high fidelity initialization coherent control. These capabilities pave way towards scalable multi-photon...
We demonstrate full charge control, narrow optical linewidths, and spin pumping on single self-assembled InGaAs quantum dots embedded in a $162.5\,\text{nm}$ thin diode structure. The are just $88\,\text{nm}$ from the top GaAs surface. design realize p-i-n-i-n that allows single-electron charging of at close-to-zero applied bias. In operation, current flow through device is extremely small resulting low noise. resonance fluorescence, we measure linewidths below $2\,\mu\text{eV}$, factor two...
The Stranski-Krastanov (SK) growth-mode facilitates the self-assembly of quantum dots (QDs) using lattice-mismatched semiconductors, for instance InAs and GaAs. SK QDs are defect-free can be embedded in heterostructures nano-engineered devices. excellent photon emitters: QD-excitons, electron-hole bound pairs, exploited as emitters high quality single photons communication. One significant drawback SK-mode is wetting layer (WL). WL results a continuum rather close energy to...
The study of percolation phenomena has various applications ranging from social networks or materials science to quantum information. most common models are bond site for which the Newman-Ziff algorithm enables an efficient simulation. Here, we consider several nonstandard that appear in context measurement-based photonic computing with so-called graph states and fusion networks. associated thresholds determine tolerance photon loss such systems develop modifications efficiently perform...
Precise control of the properties semiconductor quantum dots (QDs) is vital for creating novel devices photonics and advanced opto-electronics. Suitable low QD-densities single QD experiments are challenging to during epitaxy typically found only in limited regions wafer. Here, we demonstrate how conventional molecular beam (MBE) can be used modulate density optically active QDs one- two- dimensional patterns, while still retaining excellent quality. We find that material thickness gradients...
We present near-unity two-photon interference visibilities for single-photon states generated from two separate GaAs quantum dots. This level of visibility is the first its kind among solid-state emitters and matches performance pure platforms such as atoms ions.
A semiconductor quantum dot (QD) can generate highly indistinguishable single photons at a high rate. For application in communication and integration hybrid systems, control of the QD optical properties is essential. Understanding connection between growth process therefore important. Here, we show for GaAs QDs, grown by infilling droplet-etched nanoholes, that emission wavelength, neutral-to-charged exciton splitting, diamagnetic shift are strongly correlated with capture-zone area, an...
A hybrid system of a semiconductor quantum dot single photon source and rubidium memory represents promising architecture for future photonic repeaters. One the key challenges lies in matching emission frequency dots with transition atoms while preserving relevant properties. Here, we demonstrate bidirectional tuning from narrow-linewidth (close-to-transform-limited) dot. The is based on piezoelectric strain-amplification device, which can apply significant stress to thick bulk samples....
A deterministic source of coherent single photons is an enabling device quantum-information processing for quantum simulators, and ultimately a full-fledged internet. Quantum dots (QDs) in nanophotonic structures have been employed as excellent sources photons, planar waveguides are well suited scaling up to multiple emitters exploring near-unity photon-emitter coupling advanced active on-chip functionalities. An ideal single-photon requires suppressing noise decoherence, which notably has...
In this submission, we discuss the growth of charge-controllable GaAs quantum dots embedded in an n-i-p diode structure, from perspective a molecular beam epitaxy grower. The QDs show no blinking and narrow linewidths. We that parameters used led to bimodal mode resulting low arsenic surface coverage. identify one modes as showing good properties found previous work. As morphology fabricated does not hint at outstanding properties, attribute performance sample impurity levels matrix material...
Abstract In a radiative Auger process, optical decay leaves other carriers in excited states, resulting weak red-shifted satellite peaks the emission spectrum. The appearance of directly leads to question if process can be inverted: simultaneous photon absorption and electronic demotion. However, excitation transition has not been shown, neither on atoms nor solid-state quantum emitters. Here, we demonstrate driving transition, linking few-body Coulomb interactions optics. We perform our...
Spin-photon interfaces based on an (In,Ga)As quantum dot coupled to a waveguide are promising avenue toward scalable information processing, but coherent control of the spin state is challenging, because complicated near-to-far-field polarization transformation induced by waveguide. The authors search for particular light that excites circular dipole in dot, and use this electron's spin. They obtain coherence time 2.2 ns, comparable typical value bulk media. authors' method...
The optical spectrum of a quantum dot is typically dominated by the fundamental transition between lowest-energy configurations. However, radiative Auger process can result in additional redshifted emission lines. origin these lines combination Coulomb interaction and symmetry breaking dot. In this paper, we present measurements such for range InGaAs/GaAs self-assembled dots. We account with tight-binding model configuration including via alloy disorder. show that accounts intensities...