32 research outputs found
Management of the orbital angular momentum of vortex beams in a quadratic nonlinear interaction
Light intensity control of the orbital angular momentum of the fundamental
beam in a quadratic nonlinear process is theoretically and numerically
presented. In particular we analyzed a seeded second harmonic generation
process in presence of orbital angular momentum of the interacting beams due
both to on axis and off axis optical vortices. Examples are proposed and
discussed
Photoacoustic technique for the characterization of plasmonic properties of 2D periodic arrays of gold nanoholes
We apply photo-acoustic (PA) technique to examine plasmonic properties of 2D
periodic arrays of nanoholes etched in gold/chromium layer upon a glass substrate
Quantum computing teaching with CoSpaces
The first prototypes of quantum computers sparked interest in quantum
computing and the basic principles of quantum mechanics. The education project
on the physical bases of quantum computing is part of this context, based on
the experimental description with virtual methods of the physical
implementation of Di Vincenzo's first 5 principles. The computation process is
implemented as transformations of qubits encoded in the polarization of optical
photons. These transformations are implemented as quantum gates made as 3D
virtual objects using Blender. In detail, the models of: Laser Ar +, PBS, HWP /
QWP, BBO, APD, SMF, Control electronics are made. With the 3D models, a virtual
laboratory has been created within CoSpaces where it is possible to become
familiar with the basic processes of quantum computing: production of announced
photons, transformation of a qubit, measurement of a qubit, production of
entangled photons, transformation of two qubits, measure of two qubits. The
realization of physical models to be used in the metaverse could fill the
didactic void due to the absence of quantum optics laboratories
Orbital Angular Momentum in Noncollinear Second Harmonic Generation by off-axis vortex beams
We experimentally study the behavior of orbital angular momentum (OAM) of
light in a noncollinear second harmonic generation (SHG) process. The
experiment is performed by using a type I BBO crystal under phase matching
conditions with femtosecond pumping fields at 830 nm. Two specular off-axis
vortex beams carrying fractional orbital angular momentum at the fundamental
frequency (FF) are used. We analyze the behavior of the OAM of the SH signal
when the optical vortex of each input field at the FF is displaced from the
beam's axis. We obtain different spatial configurations of the SH field, always
carrying the same zero angular momentum.Comment: 9 pages, 7 figure
Detection of second-order nonlinear optical magnetization by mapping normalized Stokes parameters
A measurable magnetic (nonlocal) contribution to the second harmonic generation (SHG) of nonmagnetic materials is an intriguing issue related to chiral materials, such as biomolecules. Here we report the detection of an intensity-dependent optically induced magnetization of a chiral bacteriorhodopsin film under femtosecond pulse excitation (830 nm) and far from the material's resonance. The analysis of the pump intensity-dependent noncollinear SHG signal, by means of the polarization map of normalized Stokes parameters, allows one to improve the detection of the nonlinear optical magnetization M (2 omega) contribution to the SHG signal. (c) 2013 Optical Society of Americ
Direct measurement of non-linear properties of bipartite quantum states
Non-linear properties of quantum states, such as entropy or entanglement,
quantify important physical resources and are frequently used in quantum
information science. They are usually calculated from a full description of a
quantum state, even though they depend only on a small number parameters that
specify the state. Here we extract a non-local and a non-linear quantity,
namely the Renyi entropy, from local measurements on two pairs of polarization
entangled photons. We also introduce a "phase marking" technique which allows
to select uncorrupted outcomes even with non-deterministic sources of entangled
photons. We use our experimental data to demonstrate the violation of entropic
inequalities. They are examples of a non-linear entanglement witnesses and
their power exceeds all linear tests for quantum entanglement based on all
possible Bell-CHSH inequalities.Comment: To appear on PRL with minor change
Experimental noise-resistant Bell-inequality violations for polarization-entangled photons
We experimentally demonstrate that violations of Bell's inequalities for
two-photon polarization-entangled states with colored noise are extremely
robust, whereas this is not the case for states with white noise. Controlling
the amount of noise by using the timing compensation scheme introduced by Kim
et al. [Phys. Rev. A 67, 010301(R) (2003)], we have observed violations even
for states with very high noise, in excellent agrement with the predictions of
Cabello et al. [Phys. Rev. A 72, 052112 (2005)].Comment: REVTeX4, 5 pages, 4 figure