50 research outputs found
On-chip III-V monolithic integration of heralded single photon sources and beamsplitters
We demonstrate a monolithic III-V photonic circuit combining a heralded
single photon source with a beamsplitter, at room temperature and telecom
wavelength. Pulsed parametric down-conversion in an AlGaAs waveguide generates
counterpropagating photons, one of which is used to herald the injection of its
twin into the beamsplitter. We use this configuration to implement an
integrated Hanbury-Brown and Twiss experiment, yielding a heralded second-order
correlation that confirms single-photon
operation. The demonstrated generation and manipulation of quantum states on a
single III-V semiconductor chip opens promising avenues towards real-world
applications in quantum information
Hybrid III-V/Silicon photonic circuits embedding generation and routing of entangled photon pairs
The demand for integrated photonic chips combining the generation and
manipulation of quantum states of light is steadily increasing, driven by the
need for compact and scalable platforms for quantum information technologies.
While photonic circuits with diverse functionalities are being developed in
different single material platforms, it has become crucial to realize hybrid
photonic circuits that harness the advantages of multiple materials while
mitigating their respective weaknesses, resulting in enhanced capabilities.
Here, we demonstrate a hybrid III-V/Silicon quantum photonic device combining
the strong second-order nonlinearity and compliance with electrical pumping of
the III-V semiconductor platform with the high maturity and CMOS compatibility
of the silicon photonic platform. Our device embeds the spontaneous parametric
down-conversion (SPDC) of photon pairs into an AlGaAs source and their
subsequent routing to a silicon-on-insulator circuitry, within an evanescent
coupling scheme managing both polarization states. This enables the on-chip
generation of broadband telecom photons by type 0 and type 2 SPDC from the
hybrid device, at room temperature and with internal pair generation rates
exceeding for both types, while the pump beam is strongly
rejected. Two-photon interference with 92% visibility (and up to 99% upon 5 nm
spectral filtering) proves the high energy-time entanglement quality
characterizing the produced quantum state, thereby enabling a wide range of
quantum information applications on-chip, within an hybrid architecture merging
the assets of two mature and highly complementary platforms in view of
out-of-the-lab deployment of quantum technologies
Groundwater of Rome
This paper describes the contents of the new Hydrogeological Map of the City of Rome (1:50,000 scale). The map extends to the entire municipality (1285 km2) and is based on both the most recent scientific studies on the groundwater field and new survey activities carried out in order to fill the data gaps in several areas of the examined territory. The map is the result of a combination of different urban groundwater expertise and Geographic Information System (GIS)-based mapping performed using the most recent available data and has been produced with the intention of furnishing the City of Rome with the most recent and updated information regarding groundwater
A database of the coseismic effects following the 30 October 2016 Norcia earthquake in Central Italy
We provide a database of the coseismic geological surface effects following the Mw 6.5 Norcia earthquake that hit central Italy on 30 October 2016. This was one of the strongest seismic events to occur in Europe in the past thirty years, causing complex surface ruptures over an area of >400 km 2. The database originated from the collaboration of several European teams (Open EMERGEO Working Group; about 130 researchers) coordinated by the Istituto Nazionale di Geofisica e Vulcanologia. The observations were collected by performing detailed field surveys in the epicentral region in order to describe the geometry and kinematics of surface faulting, and subsequently of landslides and other secondary coseismic effects. The resulting database consists of homogeneous georeferenced records identifying 7323 observation points, each of which contains 18 numeric and string fields of relevant information. This database will impact future earthquake studies focused on modelling of the seismic processes in active extensional settings, updating probabilistic estimates of slip distribution, and assessing the hazard of surface faulting
Bound-to-continuum terahertz quantum cascade laser with a single-quantum-well phonon extraction injection stage
A terahertz quantum cascade laser design that combines a wide gain bandwidth, large photon-driven transport and good high-temperature characteristics is presented. It relies on a diagonal transition between a bound state and doublet of states tunnel coupled to the upper state of a phonon extraction stage. The high optical efficiency of this design enables the observation of photon-driven transport over a wide current density range. The relative tolerance of the design to small variations in the barrier thicknesses made it suitable for testing different growth techniques and materials. In particular, we compared the performances of devices grown using molecular-beam epitaxy with those achieved using organometallic chemical vapor deposition. The low-threshold current density and the high slope efficiency makes this device an attractive active region for the development of single-mode quantum cascade lasers based on third-order-distributed feedback structures. Single-mode, high power was achieved with good continuous and pulsed wave operation