373 research outputs found
Experimental realization of a low-noise heralded single photon source
We present a heralded single-photon source with a much lower level of
unwanted background photons in the output channel by using the herald photon to
control a shutter in the heralded channel. The shutter is implemented using a
simple field programable gate array controlled optical switch.Comment: 4 pages, 5 figure
Toward third order ghost imaging with thermal light
Recently it has been suggested that an enhancement in the visibility of ghost
images obtained with thermal light can be achieved exploiting higher order
correlations [3]. This paper reports on the status of an higher order ghost
imaging experiment carried on at INRIM labs exploiting a pseudo-thermal source
and a CCD camera.Comment: To be published in Proceedings of Recent advances in Foundations of
Quantum Mechanics and Quantum Informatio
Experimental Quantum Imaging exploiting multi-mode spatial correlation of twin beams
Properties of quantum states have disclosed new and revolutionary
technologies, ranging from quantum information to quantum imaging. This last
field is addressed to overcome limits of classical imaging by exploiting
specific properties of quantum states of light. One of the most interesting
proposed scheme exploits spatial quantum correlations between twin beams for
realizing sub-shot-noise imaging of the weak absorbing objects, leading ideally
to a noise-free imaging. Here we discuss in detail the experimental realization
of this scheme, showing its capability to reach a larger signal to noise ratio
with respect to classical imaging methods and, therefore, its interest for
future practical applications
Revealing interference by continuous variable discordant states
In general, a pair of uncorrelated Gaussian states mixed in a beam splitter
produces a correlated state at the output. However, when the inputs are
identical Gaussian states the output state is equal to the input, and no
correlations appear, as the interference had not taken place. On the other
hand, since physical phenomena do have observable effects, and the beam
splitter is there, a question arises on how to reveal the interference between
the two beams. We prove theoretically and demonstrate experimentally that this
is possible if at least one of the two beams is prepared in a discordant, i.e.
Gaussian correlated, state with a third beam. We also apply the same technique
to reveal the erasure of polarization information. Our experiments involves
thermal states and the results show that Gaussian discordant states, even when
they show a positive Glauber P-function, may be useful to achieve specific
tasks.Comment: published versio
Investigation of new methods for numerical stochastic perturbation theory in φ4 theory
Numerical stochastic perturbation theory is a powerful tool for estimating
high-order perturbative expansions in lattice field theory. The standard
algorithms based on the Langevin equation, however, suffer from several
limitations which in practice restrict the potential of this technique. In this
work we investigate some alternative methods which could in principle improve
on the standard approach. In particular, we present a study of the recently
proposed Instantaneous Stochastic Perturbation Theory, as well as a formulation
of numerical stochastic perturbation theory based on Generalized Hybrid
Molecular Dynamics algorithms. The viability of these methods is investigated
in theory.Comment: 45 pages, 12 figures. Added new section on cost comparison with
Langevin NSPT. Matches published versio
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