A5027847749- Quantum Information and Cryptography
- Semiconductor Quantum Structures and Devices
- Quantum optics and atomic interactions
- Semiconductor Lasers and Optical Devices
- Quantum Mechanics and Applications
- Quantum Computing Algorithms and Architecture
- Photonic and Optical Devices
- Quantum and electron transport phenomena
- Neural Networks and Reservoir Computing
- Quantum Dots Synthesis And Properties
- Terahertz technology and applications
- GaN-based semiconductor devices and materials
- 2D Materials and Applications
- Mechanical and Optical Resonators
- MXene and MAX Phase Materials
- Advancements in Semiconductor Devices and Circuit Design
- Optical Polarization and Ellipsometry
- Random lasers and scattering media
- Nanowire Synthesis and Applications
- Superconducting and THz Device Technology
- Spectroscopy and Laser Applications
- Orbital Angular Momentum in Optics
- Scientific Computing and Data Management
- Metal and Thin Film Mechanics
- Semiconductor materials and devices
Sapienza University of Rome
2019-2024
University College Cork
2021
University of Milano-Bicocca
2016-2020
Johannes Kepler University of Linz
2017
Quantum key distribution---exchanging a random secret relying on quantum mechanical resource---is the core feature of secure networks. Entanglement-based protocols offer additional layers security and scale favorably with repeaters, but stringent requirements set photon source have made their use situational so far. Semiconductor-based emitters are promising solution in this scenario, ensuring on-demand generation near-unity-fidelity entangled photons record-low multi-photon emission, latter...
Photonic entanglement swapping, the procedure of entangling photons without any direct interaction, is a fundamental test quantum mechanics and an essential resource to realization networks. Probabilistic sources nonclassical light were used for seminal demonstration but applications in technologies demand push-button operation requiring single emitters. This, however, turned out be extraordinary challenge due stringent prerequisites on efficiency purity generation entangled states. Here we...
The generation and long-haul transmission of highly entangled photon pairs is a cornerstone emerging photonic quantum technologies with key applications such as distribution distributed computing. However, natural limit for the maximum distance inevitably set by attenuation in medium. A network repeaters containing multiple sources photons would allow overcoming this limit. For purpose, requirements on source's brightness pairs' degree entanglement indistinguishability are stringent. Despite...
Large-scale integration of MoS2 in electronic devices requires the development reliable and cost-effective deposition processes, leading to uniform layers on a wafer scale. Here we report detailed study heterogeneous vapor–solid reaction between pre-deposited molybdenum solid film sulfur vapor, thus resulting controlled growth films onto SiO2/Si substrates with tunable thickness cm2-scale uniformity. Based Raman spectroscopy photoluminescence, show that degree crystallinity is dictated by...
Several semiconductor quantum dot techniques have been investigated for the generation of entangled photon pairs. Among other techniques, droplet epitaxy enables control shape, size, density, and emission wavelength emitters. However, fraction entanglement-ready dots that can be fabricated with this method is still limited to around 5%, matching energy photons atomic transitions (a promising route towards networking) remains an outstanding challenge. Here, we overcome these obstacles by...
Abstract Efficient all-photonic quantum teleportation requires fast and deterministic sources of highly indistinguishable entangled photons. Solid-state-based emitters—notably semiconductor dots—are a promising candidate for the role. However, despite remarkable progress in nanofabrication, proof-of-concept demonstrations have highlighted that imperfections emitter still place major roadblock way applications. Here, rather than focusing on source optimization strategies, we deal with study...
Abstract Entanglement-based quantum key distribution can enable secure communication in trusted node-free networks and over long distances. Although implementations exist both fiber free space, the latter approach is often considered challenging due to environmental factors. Here, we implement a protocol during daytime for first time using dot source. This technology presents advantages terms of narrower spectral bandwidth—beneficial filtering out sunlight—and negligible multiphoton emission...
Abstract A quantum-light source that delivers photons with a high brightness and degree of entanglement is fundamental for the development efficient entanglement-based quantum-key distribution systems. Among all possible candidates, epitaxial quantum dots are currently emerging as one brightest sources highly entangled photons. However, optimization both requires different technologies difficult to combine in scalable manner. In this work, we overcome challenge by developing novel device...
Abstract We introduce a high–temperature droplet epitaxy procedure, based on the control of arsenization dynamics nanoscale droplets liquid Ga GaAs(111)A surfaces. The use high temperatures for self-assembly quantum dots solves major issues related to material defects, introduced during fabrication process, which limited its single and entangled photon sources photonics applications. identify region in parameter space allows self–assemble with desired emission wavelength highly symmetric...
Abstract The realization of a functional quantum repeater is one the major research goals in long-distance communication. Among different approaches that are being followed, relying on memories interfaced with deterministic emitters considered as most promising solutions. In this work, we focus hardware to implement memory-based quantum-repeater schemes rely semiconductor dots (QDs) for generation polarization entangled photons. Going through relevant figures merit related efficiency photon...
Semiconductor quantum dots are currently emerging as one of the most promising sources non-classical light on which to base future networks. They can generate single photons well pairs entangled with unprecedented brightness, indistinguishability, and degree entanglement. These features have very recently opened up possibility perform advanced optics protocols that were previously inaccessible emitters. In this work, we report two experiments use non-local properties entanglement teleport...
Quantum networks play a crucial role in distributed quantum information processing, enabling the establishment of entanglement and communication among distant nodes. Fundamentally, with independent sources allow for new forms nonlocality, beyond paradigmatic Bell’s theorem. Here we implement simplest such networks—the bilocality scenario—in an urban network connecting different buildings fully scalable hybrid approach. Two using technologies—a dot nonlinear crystal—are used to share photonic...
We investigate the effect of multiphoton emission on polarization-entangled photon pairs from a coherently driven quantum dot by comparing state tomography and second-order autocorrelation measurements as function excitation power. observe that relative (absolute) probability is low...
Excitons in quantum dots are excellent sources of polarization-entangled photon pairs, but a quantitative understanding their interaction with the nuclear spin bath is still missing. Here we investigate role hyperfine energy shifts using experimentally accessible parameters and derive an upper limit to achievable entanglement fidelity. Our results consistent all available literature, indicate that noise often dominant process limiting InGaAs dots, suggest routes alleviate its effect.
GaAs quantum dots (QDs) have recently emerged as state-of-the-art semiconductor sources of polarization-entangled photon pairs, however, without site-control capability. In this work, we present a systematic study epitaxially grown GaAs/AlxGa1-xAs site-controlled pyramidal QDs possessing unrivaled excitonic uniformity in comparison to their InGaAs counterparts or fabricated by other techniques. We experimentally and systematically investigated the binding energy biexcitons, highlighting...
The control over the spectral broadening of an ensemble emitters, mainly attributable to size and shape dispersion homogenous mechanisms, is crucial several applications quantum dots. We present a convenient self-assembly approach deliver strain-free GaAs dots with distribution below 15%, due growth parameters during preliminary formation Ga droplets. This results in photoluminescence linewidth 19 meV at 14 K. narrow emission band absence wetting layer promoting dot-dot coupling allow us...
Photonic quantum information processing in metropolitan networks lays the foundation for cloud computing [1, 2], secure communication [3, 4], and realization of a global internet [5, 6]. This paradigm shift requires on-demand high-rate generation flying qubits their state teleportation over long distances [7]. Despite last decade has witnessed an impressive progress performances deterministic photon sources [8-11], exploitation distinct emitters to implement all-photonic among distant...
Two-photon resonant excitation of the biexciton-exciton cascade in a quantum dot generates highly polarization-entangled photon pairs near-deterministic way. However, ultimate level achievable entanglement is still debated. Here, we observe impact laser-induced AC-Stark effect on emission spectra and entanglement. For increasing pulse-duration/lifetime ratios pump powers, decreasing values concurrence are recorded. Nonetheless, additional contributions required to fully account for observed...
Using atomistic, million-atom screened pseudopotential theory together with configuration interaction, as well atomically resolved structures based on experimental characterization, we perform numerical calculations self-assembled $\mathrm{GaAs}/{\mathrm{Al}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{As}$(111) quantum dots that compare our data. We show random alloy disorder in the barrier can cause a symmetry breaking at single-particle level (distortions of wave functions and lifting...
Two-photon resonant excitation of the biexciton-exciton cascade in a quantum dot generates highly polarization-entangled photon pairs near-deterministic way. However, ultimate level achievable entanglement is still debated. Here, we observe impact laser-induced ac-Stark effect on emission spectra and entanglement. For increasing pulse-duration-to-lifetime ratios pump powers, decreasing values concurrence are recorded. Nonetheless, additional contributions required to fully account for...
A hybrid metal-semiconductor nanosystem for the generation of THz radiation, based on fabrication GaAs quantum molecules-Ga metal nanoparticles complexes through a self assembly approach, is proposed. The role growth parameters, substrate temperature, Ga and As flux during dot molecule (QDM) nanoparticle alignment are discussed. tuning relative positioning QDMs obtained careful control droplet nucleation sites via surface diffusion. electronic structure typical QDM was evaluated base...
We present the design for a novel type of dual-band photodetector in thermal infrared spectral range, Optically Controlled Dual-band quantum dot Infrared Photodetector (OCDIP). This concept is based on ensemble with unimodal size distribution, whose absorption spectrum can be controlled by optically injected carriers. An external pumping laser varies electron density QDs, permitting to control available electronic transitions and thus spectrum. grew test sample which we studied AFM...
A quantum-light source that delivers photons with a high brightness and degree of entanglement is fundamental for the development efficient entanglement-based quantum-key distribution systems. Among all possible candidates, epitaxial quantum dots are currently emerging as one brightest sources highly entangled photons. However, optimization both requires different technologies difficult to combine in scalable manner. In this work, we overcome challenge by developing novel device consisting...
Excitons in quantum dots are excellent sources of polarization-entangled photon pairs, but a quantitative understanding their interaction with the nuclear spin bath is still missing. Here we investigate role hyperfine energy shifts using experimentally accessible parameters and derive an upper limit to achievable entanglement fidelity. Our results consistent all available literature, indicate that spin-noise often dominant process limiting InGaAs dots, suggest routes alleviate its effect.