A5083856041- Semiconductor Quantum Structures and Devices
- Quantum and electron transport phenomena
- Strong Light-Matter Interactions
- Physics of Superconductivity and Magnetism
- Advancements in Semiconductor Devices and Circuit Design
- Advanced Semiconductor Detectors and Materials
- Plasmonic and Surface Plasmon Research
- Mechanical and Optical Resonators
- Thermal Radiation and Cooling Technologies
- Photonic and Optical Devices
- Semiconductor materials and devices
- Quantum Information and Cryptography
- Photonic Crystals and Applications
- Nanowire Synthesis and Applications
- Surface and Thin Film Phenomena
- GaN-based semiconductor devices and materials
- Topological Materials and Phenomena
- Electronic and Structural Properties of Oxides
- Spectroscopy and Laser Applications
- Semiconductor Lasers and Optical Devices
- Metamaterials and Metasurfaces Applications
- Molecular Junctions and Nanostructures
- Semiconductor materials and interfaces
- Integrated Circuits and Semiconductor Failure Analysis
- Radiation Detection and Scintillator Technologies
Istituto Officina dei Materiali
2016-2025
National Research Council
2018-2025
AREA Science Park
2015-2024
Tecnologie Avanzate (Italy)
1992-2022
Think-tank for Action on Social Change
2013-2022
Vitenparken
2022
Scuola Normale Superiore
2003-2015
Istituto Nanoscienze
2012-2015
Princeton University
2012
Istituto Nazionale per la Fisica della Materia
1992-2008
In a microcavity, light-matter coupling is quantified by the vacuum Rabi frequency $\Omega_R$. When $\Omega_R$ larger than radiative and non-radiative loss rates, system eigenstates (polaritons) are linear superposition of photonic electronic excitations, condition actively investigated in diverse physical implementations. Recently, quantum electrodynamic regime (ultra-strong coupling) was predicted when becomes comparable to transition frequency. Here we report unambiguous signatures this...
The optical response of the intersubband excitation multiple two-dimensional electron gases within a semiconductor microcavity has been studied through angle-dependent reflectance measurements. Using resonator based on total internal reflection, clear splitting about 14 meV coupled cavity modes is observed from 10 K to room temperature, with resulting polaritonlike dispersion. experimental findings are in good agreement theoretical calculations performed transfer-matrix formalism.
We present an analytic model that explains the self-ordering of quantum nanostructures grown on nonplanar surfaces. Self-limiting growth in these structures results from interplay among growth-rate anisotropy, curvature-induced capillarity, and, for alloys, entropy mixing effects. Experimental self-limiting organometallic chemical vapor deposition corrugated surfaces are quantitative agreement with model. The implications characteristics wells, wires, and dots discussed.
The authors demonstrate the deterministic coupling between a single, site-controlled InGaAs∕GaAs pyramidal quantum dot (QD) and photonic crystal membrane cavity defect. growth of self-ordered QDs in small (300nm base side) tetrahedral recesses etched on (111)B GaAs substrates was developed order to allow their integration within thin membranes. Accurate (better than 50nm) positioning QD with respect optical mode is achieved reproducibly owing site control. Coupling emission evidenced...
We demonstrate that the emission characteristics of site-controlled InGaAs/GaAs single quantum dots embedded in photonic crystal slab cavities correspond to confined excitons coupled cavity modes, unlike previous reports similar systems based on self-assembled dots. By using polarization-resolved photoluminescence spectroscopy at different temperatures and a theoretical model, we show exciton-cavity interaction range is limited phonon sidebands. Photon-correlation pump-power dependence...
We demonstrate mid-infrared detectors embedded into an array of double-metal nano-antennas. The antennas act as microcavities that squeeze the electric field thin semiconductor layers, thus enhancing detector responsivity. Furthermore, thanks to ability gather photons from area larger than device's physical dimensions, dark current is reduced without hindering photo-generation rate. In these devices, background-limited performance improved with a consequent increase operating temperature....
Polaritons reach the quantum limit, providing a new and promising platform of strongly coherent interacting particles.
Applications relying on mid-infrared radiation (Mid-IR, $\lambda\sim$ 3-30 $\mu$m) have progressed at a very rapid pace in recent years, stimulated by scientific and technological breakthroughs. Mid-IR cameras propelled the field of thermal imaging. And invention quantum cascade laser (QCL) has been milestone, making compact, semiconductor-based mid-IR lasers available to vast range applications. All breakthrough advances stemmed from development transformative technology. In addition...
An interplay of geometrical frustration and strong quantum fluctuations in a spin-1/2 triangular-lattice antiferromagnet (TAF) can lead to exotic states. Here, we report the neutron-scattering, magnetization, specific heat, magnetocaloric studies recently discovered TAF Na 2 BaCo(PO 4 ) , which be described by easy axis XXZ model. The zero-field neutron diffraction experiment reveals an incommensurate antiferromagnetic ground state with significantly reduced ordered moment about 0.54(2) μ B...
We have developed an analytic model that describes in detail the establishment of self-ordered profiles during semiconductor epitaxy on corrugated surfaces. Lateral, derives from surface gradients chemical potential due to nonplanarity profile (capillarity). The growth rate variation different facets composing determines whether sharpens up at bottom grooves or apex corrugations. For alloy growth, additional entropy mixing effects affect shape and composition. predictions were applied...
The structure of GaAs/AlGaAs quantum wires (QWRs) and vertical wells (VQWs) grown by low-pressure organometallic chemical vapor deposition was investigated conventional high resolution transmission electron microscopy, low-temperature cathodoluminescence. lower wire boundaries show a much smaller radius curvature, as compared with atmospheric pressure growth similar structures, the upper distinct faceting. More abrupt interfaces are obtained due to kinetically limited growth, measured...
We demonstrate the external control of coupling between intersubband transition and photonic mode a GaAs∕AlGaAs microcavity with multiple quantum wells embedded. By electrical gating, charge density in can be lowered, thereby quenching polaritons reverting system to uncoupled excitations. The angle-dependent reflectance measurements are good agreement theoretical calculations performed transfer matrix formalism. experiment shows prospects offered by microcavities through manipulation ground state.
We introduce and experimentally demonstrate a new method that allows us to controllably couple copropagating spin-resolved edge states of two-dimensional electron gas (2DEG) in the integer quantum Hall regime. The scheme exploits spatially periodic in-plane magnetic field is created by an array Cobalt nanomagnets placed at boundary 2DEG. A maximum charge or spin transfer $28\ifmmode\pm\else\textpm\fi{}1%$ achieved 250 mK.
In this article we have investigated two important properties of metallic nano-resonators which can substantially improve the temperature performances infrared quantum detectors. The first is antenna effect that increases effective surface photon collection and second subwavelength confinement compresses radiation into very small volumes interaction. To quantify our analysis defined discussed figures merit, area Acoll focusing factor F. Both quantities depend solely on geometrical parameters...
Hybrid superconductor/semiconductor devices constitute a powerful platform where intriguing topological properties can be investigated. Here we present fabrication methods and analysis of Josephson junctions formed by high-mobility InAs quantum-well bridging two Nb superconducting contacts. We demonstrate supercurrent flow with transport measurements, critical temperature 8.1 K, fields the order 3 T. Modulation amplitude achieved acting on side gates lithographed close to two-dimensional...
The ultrafast scattering dynamics of intersubband polaritons in dispersive cavities embedding GaAs/AlGaAs quantum wells are studied directly within their band structure using a non-collinear pump-probe geometry with phase-stable mid-infrared pulses. Selective excitation the lower polariton at frequency ~25 THz and finite in-plane momentum, $k_{||}$, leads to emergence narrowband maximum probe reflectivity $k_{||}=0$. A mechanical model identifies underlying microscopic process as stimulated...
We demonstrate that absorption saturation of a mid-infrared intersubband transition can be engineered to occur at moderate light intensities the order 10–20 kW cm−2 and room temperature. The structure consists an array metal–semiconductor–metal patches hosting judiciously designed 253 nm thick GaAs/AlGaAs semiconductor heterostructure. At low incident intensity, operates in strong light–matter coupling regime exhibits two peaks wavelengths close 8.9 μm. Saturation appears as weak regime—and...
We have investigated the transition from strong to ultra-strong coupling regime between a mid-infrared intersubband excitation and fundamental mode of metal-dielectric-metal microcavity. The is demonstrated up room temperature for wavelength $11.7 \mu$m by using 260 nm thick cavities, which impose an extreme sub-wavelength confinement. By varying doping our structures we show that experimental signature opening photonic gap in polariton dispersion. width this depends quadratically on ratio...