63 research outputs found
Mesoscopic States of Light for the Detection of Weakly Absorbing Objects
Over the past twenty years, different imaging techniques have been proposed and implemented in order to reconstruct the images of different kinds of objects, including faint ones. In this work, we exploit the mesoscopic intensity domain to prove that the determination of the transmittance efficiency of an object can be obtained by considering the calculation of the noise reduction factor in the case of a multi-mode pseudothermal state divided at a balanced beam splitter and detected by photon-number-resolving detectors. The good quality of the experimental results suggests that this strategy can be extended to the determination of a matrix of different transmittance values by means of arrays of photon-number-resolving detectors
Gaussian and Non-Gaussian operations on non-Gaussian state: engineering non-Gaussianity
Multiple photon subtraction applied to a displaced phase-averaged coherent
state, which is a non-Gaussian classical state, produces conditional states
with a non trivial (positive) Glauber-Sudarshan -representation. We
theoretically and experimentally demonstrate that, despite its simplicity, this
class of conditional states cannot be fully characterized by direct detection
of photon numbers. In particular, the non-Gaussianity of the state is a
characteristics that must be assessed by phase-sensitive measurements. We also
show that the non-Gaussianity of conditional states can be manipulated by
choosing suitable conditioning values and composition of phase-averaged states
Towards underwater quantum communication in the mesoscopic intensity regime
The problem of secure underwater communication can take advantage of the exploitation of quantum resources and novel quantum technologies. At variance with the current experiments performed at the single photon level, here we propose a different scenario involving mesoscopic twin-beam states of light and two classes of commercial photon-number-resolving detectors. We prove that twin-beam states remain nonclassical even if the signal propagates in tubes filled with water, while the idler is transmitted in free space. We also demonstrate that from the study of the nonclassicality information about the loss and noise sources affecting the transmission channels can be successfully extracted
Novel scheme for secure data transmission based on mesoscopic twin beams and photon-number-resolving detectors
Quantum resources can improve the quality and security of data transmission. A novel communication protocol based on the use of mesoscopic twin-beam (TWB) states of light is proposed and discussed. The message sent by Alice to Bob is encoded in binary single-mode thermal states having two possible mean values, both smaller than the mean value of the TWB. Such thermal states are alternately superimposed to the portion of TWB sent to Bob. We demonstrate that in the presence of an eavesdropping attack that intercepts and substitutes part of the signal with a thermal noise, Bob can still successfully decrypt the message by evaluating the noise reduction factor for detected photons. The protocol opens new perspectives in the exploitation of quantum states of light for applications to Quantum Communication
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
Photon-number correlations by photon-number resolving detectors
We demonstrate that by using a pair of photodetectors endowed with internal
gain we are able to quantify the correlation coefficient between the two
components of a pulsed bipartite state in the mesoscopic intensity regime (less
than 100 mean photons)
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
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