arXiv subjects

Giorgio Adamo

Publications and source records attributed to Giorgio Adamo.

28 records · Page 2Linked to original sources

arXiv2020

Metamaterial enhancement of metal-halide perovskite luminescence

Metal-halide perovskites are rapidly emerging as solution-processable optical materials for light emitting applications. Here we adopt a plasmonic metamaterial approach to enhance photoluminescence emission and extraction of methylammonium lead iodide (MAPbI3) thin films, based on the Purcell effect. We show that hybridization of the active metal-halide film with resonant nanoscale sized slits carved into a gold film can yield more than one order of magnitude enhancement of luminescence intensity, and nearly threefold reduction of luminescence lifetime. This shows the effectiveness of resonant nanostructures in controlling metal-halide perovskite light emission properties over a tunable spectral range, a viable approach toward highly efficient perovskite light emitting devices and single-photon emitters.

physics.app-ph↗

arXiv2020

Plasmono-Atomic Interactions on a Fiber Tip

Light-atom interaction can be engineered by interfacing atoms with various specially designed media and optical fibers are convenient platforms for realization of compact interfaces. Here, we show that an optical fiber sensor bearing a plasmonic metasurface at its tip can be used to detect modifications of the Doppler-free hyperfine atomic spectra induced by coupling between atomic and plasmonic excitations. We observed the inversion of the phase modulation reflectivity spectra of Cesium vapor in presence of the metamaterial. This work paves the way for future compact hybrid atomic devices with a cleaved tip as substrate platform to host various two-dimensional materials.

physics.atom-ph↗

arXiv2020

Optical Metrology of Sub-Wavelength Objects Enabled by Artificial Intelligence

Microscopes and various forms of interferometers have been used for decades in optical metrology of objects that are typically larger than the wavelength of light λ. However, metrology of subwavelength objects was deemed impossible due to the diffraction limit. We report that measurement of the physical size of sub-wavelength objects with accuracy exceeding λ/800 by analyzing the diffraction pattern of coherent light scattered by the objects with deep learning enabled analysis. With a 633nm laser, we show that the width of sub-wavelength slits in opaque screen can be measured with accuracy of 0.77nm, challenging the accuracy of electron beam and ion beam lithographies. The technique is suitable for high-rate non-contact measurements of nanometric sizes in smart manufacturing applications with integrated metrology and processing tools.

physics.optics↗

arXiv2019

Phase stabilization of a coherent fibre network by single-photon counting

Coherent optical fibre networks are extremely sensitive to thermal, mechanical and acoustic noise, which requires elaborate schemes of phase stabilization with dedicated auxiliary lasers, multiplexers and photodetectors. This is particularly demanding in quantum networks operating at the single-photon level. Here we propose a simple method of phase stabilization based on single-photon counting and apply it to quantum fibre networks implementing single-photon interference on a lossless beamsplitter and coherent perfect absorption on a metamaterial absorber. As a proof of principle, we show dissipative single-photon switching with visibility close to 80%. This method can be employed in quantum networks of greater complexity without classical stabilization rigs, potentially increasing efficiency of the quantum channels.

quant-ph↗

arXiv2019

Coupling of atomic quadrupole transitions with resonant surface plasmons

We report on the coupling of an electric quadrupole transition in atom with plasmonic excitation in a nanostructured metallic metamaterial. The quadrupole transition at 685 nm in the gas of Cesium atoms is optically pumped, while the induced ground state population depletion is probed with light tuned on the strong electric dipole transition at 852 nm. We use selective reflection to resolve the Doppler-free hyperfine structure of Cesium atoms. We observed a strong modification of the reflection spectra at the presence of metamaterial and discuss the role of the spatial variation of the surface plasmon polariton on the quadrupole coupling.

physics.atom-ph↗

arXiv2018

Tailoring optical metamaterials to tune the atom-surface Casimir-Polder interaction

Metamaterials are fascinating tools that can structure not only surface plasmons and electromagnetic waves but also electromagnetic vacuum fluctuations. The possibility of shaping the quantum vacuum is a powerful concept that ultimately allows engineering the interaction between macroscopic surfaces and quantum emitters such as atoms, molecules or quantum dots. The long-range atom-surface interaction, known as Casimir-Polder interaction, is of fundamental importance in quantum electrodynamics but also attracts a significant interest for platforms that interface atoms with nanophotonic devices. Here we perform a spectroscopic selective reflection measurement of the Casimir-Polder interaction between a Cs(6P_{3/2}) atom and a nanostructured metallic planar metamaterial. We show that by engineering the near-field plasmonic resonances of the metamaterial, we can successfully tune the Casimir-Polder interaction, demonstrating both a strong enhancement and reduction with respect to its non-resonant value. We also show an enhancement of the atomic spontaneous emission rate due to its coupling with the evanescent modes of the nanostructure. Probing excited state atoms next to nontrivial tailored surfaces is a rigorous test of quantum electrodynamics. Engineering Casimir-Polder interactions represents a significant step towards atom trapping in the extreme near field, possibly without the use of external fields.

physics.atom-ph↗

arXiv2017

Room-temperature solid state quantum emitters in the telecom range

On demand single photon emitters (SPEs) play a key role across a broad range of quantum technologies, including quantum computation, quantum simulation, quantum metrology and quantum communications. In quantum networks and quantum key distribution protocols, where photons are employed as flying qubits, telecom wavelength operation is preferred due to the reduced fibre loss. However, despite the tremendous efforts to develop various triggered SPE platforms, a robust source of triggered SPEs operating at room temperature and the telecom wavelength is still missing. Here we report a triggered, optically stable, room temperature solid state SPE operating at telecom wavelengths. The emitters exhibit high photon purity (~ 5% multiphoton events) and a record-high brightness of ~ 1.5 MHz. The emission is attributed to localized defects in a gallium nitride (GaN) crystal. The high performance SPEs embedded in a technologically mature semiconductor are promising for on-chip quantum simulators and practical quantum communication technologies.

quant-ph↗

arXiv2017

Plasmonics of Topological Insulators at Optical Frequencies

The development of nanoplasmonic devices, such as plasmonic circuits and metamaterial superlenses in the visible to ultraviolet frequency range, is hampered by the lack of low-loss plasmonic media. Recently, strong plasmonic response was reported in a certain class of topological insulators. Here, we present a first-principles density functional theory analysis of the dielectric functions of topologically insulating quaternary (Bi,Sb)2(Te,Se)3 trichalcogenide compounds. Bulk plasmonic properties, dominated by interband transitions, are observed from 2-3 eV and extend to higher frequencies. Moreover, trichalcogenide compounds are better plasmonic media than gold and silver at blue and UV wavelengths. By analysing thin slabs, we also show that these materials exhibit topologically protected surface states, which are capable of supporting propagating plasmon polariton modes over an extremely broad spectral range, from the visible to the mid-infrared and beyond, owing to a combination of inter- and intra-surface band transitions.

physics.optics↗

arXiv2016

Atomic Response in the Near-field of Nanostructured Plasmonic Metamaterial

We report on reflection spectra of caesium atoms in close vicinity of a nanostructured metallic meta-surface. We show that the hyperfine sub-Doppler spectrum of the $6S_{1/2} - 6P_{3/2}$ resonance transition at 852 nm is strongly affected by the coupling to the plasmonic resonance of the nanostructure. Fine tuning of dispersion and positions of the atomic lines in the near-field of plasmonic metamaterials could have uses and implications for the atom-based metrology, sensing and the development of atom-on-a-chip devices.

cond-mat.mes-hall↗

arXiv2014

Ultraviolet and visible range plasmonics of a topological insulator

The development of metamaterials, data processing circuits and sensors for the visible and UV parts of the spectrum is hampered by the lack of low-loss media supporting plasmonic excitations and drives the intense search for plasmonic materials beyond noble metals. By studying plasmonic nanostructures fabricated on the surface of topological insulator $\mbox{Bi}_{1.5}\mbox{Sb}_{0.5}\mbox{Te}_{1.8}\mbox{Se}_{1.2}$ we found that it is orders of magnitude better plasmonic material than gold and silver in the blue-UV range. Metamaterial fabricated from $\mbox{Bi}_{1.5}\mbox{Sb}_{0.5}\mbox{Te}_{1.8}\mbox{Se}_{1.2}$ show plasmonic resonances from 350 nm to 550 nm while surface gratings exhibit cathodoluminescent peaks from 230 nm to 1050 nm. The negative permittivity underpinning plasmonic response is attributed to the combination of bulk interband transitions and surface contribution of the topologically protected states. The importance of our result is in the identification of new mechanisms of negative permittivity in semiconductors where visible-range plasmonics can be directly integrated with electronics.

physics.optics↗