0000000000067930
AUTHOR
Alessandro Settimi
Second quantization and atomic spontaneous emission inside one-dimensional photonic crystals via a quasinormal-modes approach
An extension of the second quantization scheme based on the quasinormal-modes theory to one-dimensional photonic band gap (PBG) structures is discussed. Such structures, treated as double open optical cavities, are studied as part of a compound closed system including the electromagnetic radiative external bath. The electromagnetic field inside the photonic crystal is successfully represented by a new class of modes called quasinormal modes. Starting from this representation we introduce the Feynman's propagator to calculate the decay rate of a dipole inside a PBG structure, related to the density of modes, in the presence of the vacuum fluctuations outside the one-dimensional cavity.
Coherent control of stimulated emission inside one-dimensional photonic crystals
In this paper, the quasinormal mode (QNM) theory is applied to discuss the quantum problem of an atom embedded inside a one-dimensional (1D) photonic band gap (PBG) cavity pumped by two counterpropagating laser beams. The e.m. field is quantized in terms of the QNMs in the 1D PBG and the atom modeled as a two-level system is assumed to be weakly coupled to just one of the QNMs. The main result of the paper is that the decay time depends on the position of the dipole inside the cavity, and can be controlled by the phase difference of the two laser beams.
Bedside surgery in the newborn infants: Survey of the Italian society of pediatric surgery
Abstract Introduction This is the report of the first official survey from the Italian Society of Pediatric Surgery (ISPS) to appraise the distribution and organization of bedside surgery in the neonatal intensive care units (NICU) in Italy. Methods A questionnaire requesting general data, staff data and workload data of the centers was developed and sent by means of an online cloud-based software instrument to all Italian pediatric surgery Units. Results The survey was answered by 34 (65%) out of 52 centers. NICU bedside surgery is reported in 81.8% of the pediatric surgery centers. A lower prevalence of bedside surgical practice in the NICU was reported for Southern Italy and the islands …
Work-related upper limb musculoskeletal disorders in paediatric laparoscopic surgery. A multicenter survey.
Abstract Background Surgeons are at risk for developing work-related musculoskeletal symptoms (WMS). The present study aims to examine the physical factors and their association with WMS among pediatric laparoscopic surgeons. Methods A questionnaire consisting of 21 questions was created and mailed to 25 pediatric laparoscopic surgeons (LG). 23/25 surgeons (92%) completed the survey. The questionnaire was analyzed and then split into 2 groups. Group 1 (LG1) included surgeons with greater laparoscopic experience, and group 2 (LG2) included surgeons with less important laparoscopic experience. In addition, we constructed and sent to the same surgeons a similar questionnaire focused on WMS aft…
Towards the Design of Robotic Drivers for Full-Scale Self-Driving Racing Cars
Autonomous vehicles are undergoing a rapid development thanks to advances in perception, planning and control methods and technologies achieved in the last two decades. Moreover, the lowering costs of sensors and computing platforms are attracting industrial entities, empowering the integration and development of innovative solutions for civilian use. Still, the development of autonomous racing cars has been confined mainly to laboratory studies and small to middle scale vehicles. This paper tackles the development of a planning and control framework for an electric full scale autonomous racing car, which is an absolute novelty in the literature, upon which we report our preliminary experim…
Coherent Control of Stimulated Emission inside one dimensional Photonic Crystals:Strong Coupling regime
The present paper discusses the stimulated emission, in strong coupling regime, of an atom embedded inside a one dimensional (1D) Photonic Band Gap (PBG) cavity which is pumped by two counter-propagating laser beams. Quantum electrodynamics is applied to model the atom-field interaction, by considering the atom as a two level system, the e.m. field as a superposition of normal modes, the coupling in dipole approximation, and the equations of motion in Wigner-Weisskopf and rotating wave approximations. In addition, the Quasi Normal Mode (QNM) approach for an open cavity is adopted, interpreting the local density of states (LDOS) as the local density of probability to excite one QNM of the ca…
Quantum counter-propagation in open optical cavities via the quasi-normal-mode approach
By using the quasi-normal-mode (QNM) formalism in a second quantization scheme, the problem of the counter-propagation of electromagnetic fields inside optical cavities is studied. The links between QNM operators and canonical destruction and creation operators describing the external free field, as well as the field correlation functions, are found and discussed. An application of the theory is performed for open cavities whose refractive index satisfies symmetric properties.
Coherent control of stimulated emission process inside one-dimensional photonic crystals
The control of the stimulated emission processes in a 1D PC is discussed. A non-canonical quantization is adopted (QNM). The decay rate of the stimulated emission depends on the cavity and phase-difference of the pumps.
Stimulated emission control in Photonic Crystals: Strong coupling regime in QNM approach
Stimulated emission, in strong coupling regime, in a one dimensional photonic crystals is described by considering two counter-propagating pumps. Quasi normal mode approach is used and coherent control of the Rabi splitting is discussed.
A Planning and Control System for Self-Driving Racing Vehicles
Autonomous robots will soon enter our everyday life as self-driving cars. These vehicles are designed to behave according to certain sets of cooperative rules, such as traffic ones, and to respond to events that might be unpredictable in their occurrence but predictable in their nature, such as a pedestrian suddenly crossing a street, or another car losing control. As civilian autonomous cars will cross the road, racing autonomous cars are under development, which will require superior Artificial Intelligence Drivers to perform in structured but uncertain conditions. We describe some preliminary results obtained during the development of a planning and control system as key elements of an A…
Quasi-Normal Frequencies in Open Cavities: An Application to Photonic Crystals
The electromagnetic field in an optical open cavity is analyzed in the framework of the Quasi-Normal Modes theory. The role of the complex quasi-normal frequencies in the transmission coefficient and their link with the density of quasi-modes function is clarified. An application to a quarter-wave symmetric one-dimensional photonic crystals is discussed to illustrate the usefulness and the meaning of our results.