224 research outputs found
Reliable source of conditional non-Gaussian states from single-mode thermal fields
We address both theoretically and experimentally the generation of pulsed
non-Gaussian states from classical Gaussian ones by means of conditional
measurements. The setup relies on a beam splitter and a pair of linear
photodetectors able to resolve up to tens of photons in the two outputs. We
show the reliability of the setup and the good agreement with the theory for a
single-mode thermal field entering the beam splitter and present a thorough
characterization of the photon statistics of the conditional states.Comment: 18 pages, 12 figure
Effect of noisy channels on the transmission of mesoscopic twin-beam states
Quantum properties of light, which are crucial resources for quantum technologies, are quite fragile in nature and can be degraded and even concealed by the environment. We show, both theoretically and experimentally, that mesoscopic twin-beam states of light can preserve their nonclassicality even in the presence of major losses and different types of noise, thus suggesting their potential usefulness to encode information in quantum communication protocols. We develop a comprehensive general analytical model for a measurable nonclassicality criterion and find thresholds on noise and losses for the survival of entanglement in the twin beam
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
Quantum physics at high school: a collaboration between physics researchers and teachers to design teaching - learning sequences
Quantum physics is changing the paradigms for understanding reality and is fostering scientific innovation. Nevertheless, the core concepts of the second quantum revolution are not included in the Italian physics curriculum. Our research project aims to generate the conditions for the development of the scientific competences related to the understanding of the fundamental concepts of contemporary physics at secondary school level. In the framework of Educational Reconstruction for Teacher Education (ERTE), we have developed a continuous professional development program for teachers to enable in-service physics teachers in secondary schools to introduce the superposition principle, quantum entanglement, and their technological applications into regular classroom activities. To achieve this goal, several types of activities have been planned to strengthen collaboration between high school teachers and physics researchers. The intended outcome is to create resources and materials that can help teachers and researchers create innovative physics curricula that can be used in normal secondary school teaching activities. In this paper we present the results of the first edition of a continuous professional development program for in-service teachers on introducing the superposition principle and quantum entanglement into online classroom activities during the schools Covid19 lockdown
Parallel spatial intensity correlations to decode random frequency-downconverted images
We record frequency-downconverted images that are chaotic, as they are obtained in a chi((2)) crystal from the interaction of two pulsed pseudo-thermal fields of which the one at the higher frequency encountered the imaged object. Spatial correlations of the intensity fluctuations in these chaotic images with the intensity of a single spatial Fourier component of the low-frequency input field, allow image retrieval if the number of records on which the ensemble-averages are calculated is suitably large. When it is too small to achieve a satisfactory result, we show that computing the correlations in parallel with different components of the low-frequency input field, shifting the correlation maps according to a rule suggested by 3D phase-matching, and averaging them, leads to the recovery of the downconverted image. The method can be used for secure and fast image transmission
Special issue on basics and applications in quantum optics
Quantum technologies are advancing very rapidly and have the potential to innovate communication and computing far beyond current possibilities. Among the possible plat- forms suitable to run quantum technology protocols, in the last decades quantum optics has received a lot of attention for the handiness and versatility of optical systems. In addition to studying the fundamentals of quantum mechanics, quantum optical states have been exploited for several applications, such as quantum-state engineering, quantum communication and quantum cryptography protocols, enhanced metrology and sensing, quantum optical integrated circuits, quantum imaging, and quantum biological effects. In this Special Issue, we collect some papers and also a review on some recent research activities that show the potential of quantum optics for the advancement of quantum technologies
Conditional measurements on multimode pairwise entangled states from spontaneous parametric downconversion
We address the intrinsic multimode nature of the quantum state of light
obtained by pulsed spontaneous parametric downconversion and develop a
theoretical model based only on experimentally accessible quantities. We
exploit the pairwise entanglement as a resource for conditional multimode
measurements and derive closed formulas for the detection probability and the
density matrix of the conditional states. We present a set of experiments
performed to validate our model in different conditions that are in excellent
agreement with experimental data. Finally, we evaluate nonGaussianity of the
conditional states obtained from our source with the aim of discussing the
effects of the different experimental parameters on the efficacy of this type
of conditional state preparation
Correcting Coherent Errors by Random Operation on Actual Quantum Hardware
Characterizing and mitigating errors in current noisy intermediate-scale devices is important to improve the performance of the next generation of quantum hardware. To investigate the importance of the different noise mechanisms affecting quantum computation, we performed a full quantum process tomography of single qubits in a real quantum processor in which echo experiments are implemented. In addition to the sources of error already included in the standard models, the obtained results show the dominant role of coherent errors, which we practically corrected by inserting random single-qubit unitaries in the quantum circuit, significantly increasing the circuit length over which quantum computations on actual quantum hardware produce reliable results
Experimental reconstruction of photon statistics without photon counting
Experimental reconstructions of photon number distributions of both
continuous-wave and pulsed light beams are reported. Our scheme is based on
on/off avalanche photodetection assisted by maximum-likelihood estimation and
does not involve photon counting. Reconstructions of the distribution for both
semiclassical and quantum states of light are reported for single-mode as well
as for multimode beams.Comment: Revised version: in press on PRL. 4 pages, 4 fig
Image transfer through a chaotic channel by intensity correlations
The three-wave mixing processes in a second-order nonlinear medium can be
used for imaging protocols, in which an object field is injected into the
nonlinear medium together with a reference field and an image field is
generated. When the reference field is chaotic, the image field is also chaotic
and does not carry any information about the object. We show that a clear image
of the object be extracted from the chaotic image field by measuring the
spatial intensity correlations between this field and one Fourier component of
the reference. We experimentally verify this imaging protocol in the case of
frequency downconversion.Comment: 17 pages, 7 figure
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