179 research outputs found
Photon statistics in the macroscopic realm measured without photon-counters
In a macroscopic realm, in which photons are too many for being counted by
any photon counting detector, photon statistics can be measured by using
detectors simply endowed with linear response. We insert one of such detectors
in a conventional photon-counting apparatus, which returns a voltage every time
the detector responds to light by generating a number of elementary charges via
its primary photo-detection process. We only assume that, when a single charge
is photo-generated, the probability density of the voltages is a distribution
that is narrow with respect to its mean value. Under this hypothesis the output
voltages can be suitably binned so that their probability distribution is the
same as that of the photo-generated charges, that is, of the detected photons
Light statistics by non-calibrated linear photodetectors
We theoretically demonstrate that detectors endowed with internal gain and
operated in regimes in which they do not necessarily behave as photon-counters,
but still ensure linear input/output responses, can allow a self-consistent
characterization of the statistics of the number of detected photons without
need of knowing their gain. We present experiments performed with a
photo-emissive hybrid detector on a number of classical fields endowed with
non-trivial statistics and show that the method works for both microscopic and
mesoscopic photon numbers. The obtained detected-photon probability
distributions agree with those expected for the photon numbers, which are also
reconstructed by an independent method.Comment: submitted to the special issue "Tests of foundations of Quantum
Mechanics" of "Advanced Science Letters
Intensity correlations, entanglement properties and ghost imaging in multimode thermal-seeded parametric downconversion: Theory
We address parametric-downconversion seeded by multimode pseudo-thermal
fields. We show that this process may be used to generate multimode pairwise
correlated states with entanglement properties that can be tuned by controlling
the seed intensities. Multimode pseudo-thermal fields seeded
parametric-downconversion represents a novel source of correlated states, which
allows one to explore the classical-quantum transition in pairwise correlations
and to realize ghost imaging and ghost diffraction in regimes not yet explored
by experiments.Comment: 9 pages, 3 figure
Self-consistent characterization of light statistics
We demonstrate the possibility of a self-consistent characterization of the
photon-number statistics of a light field by using photoemissive detectors with
internal gain simply endowed with linear input/output responses. The method can
be applied to both microscopic and mesoscopic photon-number regimes. The
detectors must operate in the linear range without need of photon-counting
capabilities.Comment: To be published in "Journal of Modern Optics
The quantum-classical transition in thermally seeded parametric downconversion
We address the pair of conjugated field modes obtained from
parametric-downconversion as a convenient system to analyze the
quantum-classical transition in the continuous variable regime. We explicitly
evaluate intensity correlations, negativity and entanglement for the system in
a thermal state and show that a hierarchy of nonclassicality thresholds
naturally emerges in terms of thermal and downconversion photon number. We show
that the transition from quantum to classical regime may be tuned by
controlling the intensities of the seeds and detected by intensity
measurements. Besides, we show that the thresholds are not affected by losses,
which only modify the amount of nonclassicality. The multimode case is also
analyzed in some detail.Comment: 12 pages, 3 figure
Chaotic imaging in frequency downconversion
We analyze and realize the recovery, by means of spatial intensity
correlations, of the image obtained by a seeded frequency downconversion
process in which the seed field is chaotic and an intensity modulation is
encoded on the pump field. Although the generated field is as chaotic as the
seed field and does not carry any information about the modulation of the pump,
an image of the pump can be extracted by measuring the spatial intensity
correlations between the generated field and one Fourier component of the seed
The quantum-classical transition in thermally seeded parametric downconversion
We address the pair of conjugated field modes obtained from
parametric-downconversion as a convenient system to analyze the
quantum-classical transition in the continuous variable regime. We explicitly
evaluate intensity correlations, negativity and entanglement for the system in
a thermal state and show that a hierarchy of nonclassicality thresholds
naturally emerges in terms of thermal and downconversion photon number. We show
that the transition from quantum to classical regime may be tuned by
controlling the intensities of the seeds and detected by intensity
measurements. Besides, we show that the thresholds are not affected by losses,
which only modify the amount of nonclassicality. The multimode case is also
analyzed in some detail.Comment: 12 pages, 3 figure
Sub-shot-noise photon-number correlation in mesoscopic twin-beam of light
We demonstrate sub-shot-noise photon-number correlations in a (temporal)
multimode mesoscopic ( detected photons) twin-beam produced by
ps-pulsed spontaneous non-degenerate parametric downconversion. We have
separately detected the signal and idler distributions of photons collected in
twin coherence areas and found that the variance of the photon-count difference
goes below the shot-noise limit by 3.25 dB. The number of temporal modes
contained in the twin-beam, as well as the size of the twin coherence areas,
depends on the pump intensity. Our scheme is based on spontaneous
downconversion and thus does not suffer from limitations due to the finite gain
of the parametric process. Twin-beams are also used to demonstrate the
conditional preparation of a nonclassical (sub-Poissonian) state.Comment: 5 pages, 5 (low-res) figures, to appear on PR
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