1,721,311 research outputs found
Tailoring asymmetric lossy channels to test the robustness of mesoscopic quantum states of light
Full text linkIn the past twenty years many experiments have demonstrated that quantum states of light can be used for secure data transfer, despite the presence of many noise sources. In this paper we investigate, both theoretically and experimentally, the role played by a statistically-distributed asymmetric amount of loss in the degradation of nonclassical photon-number correlations between the two parties of multimode twin-beam states in the mesoscopic intensity regime. To be as close as possible to realistic scenarios, we consider two different statistical distributions of such a loss, a Gaussian distribution and a log-normal one. The results achieved in the two cases show to what extent the involved parameters, both those connected to loss and those describing the employed states of light, preserve nonclassicality
Rainbow correlation imaging with macroscopic twin beam
No full textWe present the implementation of a correlation-imaging protocol that exploits both the spatial and spectral correlations of macroscopic twin-beam states generated by parametric downconversion. In particular, the spectral resolution of an imaging spectrometer coupled to an EMCCD camera is used in a proof-of-principle experiment to encrypt and decrypt a simple code to be transmitted between two parties. In order to optimize the trade-off between visibility and resolution, we provide the characterization of the correlation images as a function of the spatio- spectral properties of twin beams generated at different pump power values
Can nonclassical correlations survive in the presence of asymmetric lossy channels?
No full textNonclassical correlations are a fundamental resource for applications involving multipartite systems. To assess nonclassicality, several different criteria can be applied to measured data. Here we compare three inequalities by applying them to a multi-mode twin-beam state, in which one of the two parties is transmitted through a varying lossy channel. We demonstrate, both theoretically and experimentally, that the asymmetry introduced by losses affects the three criteria in different ways, thus offering a tool for quantum optics applications
Ghost imaging by intense multimode twin beam
No full textWe present the first experimental implementation of the ghost-imaging protocol based on an intense multimode spontaneous parametric down-conversion process. Temporal and spatial properties of the quantum field used in the protocol are also discussed
Direct detection of super-thermal photon-number statistics in second-harmonic generation
No full textChanges in the statistical properties of light undergoing second-harmonic generation are investigated in the photon- number-resolving domain. We theoretically demonstrate that when a portion of multimode thermal light produced by parametric down-conversion is up-converted, both the second-harmonics and the residual beam at the fundamental wavelength are endowed with super-thermal photon-number distributions. The experimental results, which were obtained by exploiting the photo-numberresolving capability of hybrid photodetectors, are in excellent agreement with the theoretical expectations
Feasibility of a Novel Quantum Communication Protocol in Jerlov Type I Water
Full text linkUnderwater communication based on the use of optical quantum resources has attracted a lot of attention in the last five years due to the potential advantages offered by quantum states of light. In this context, we propose to operate in the mesoscopic intensity regime, where the optical states are well populated and the employed detectors have photon-number resolution. By exploiting these features, we demonstrate that a novel communication protocol based on the experimental quantification of nonclassicality of mesoscopic twin-beam states can be used to transmit binary signals encoded in two single-mode pseudothermal states with different mean values through a Jerlov type I water channel. The experimental results are in perfect agreement with the developed theoretical model, and the feasibility of the protocol is also investigated as a function of the data samples corresponding to each one of the two signals. The good quality of the results encourages a more realistic implementation of the protocol, also exploring the maximum distance at which the quantum states remain nonclassical and thus can be still properly discriminated
Thermal and superthermal noise signals as resources for underwater quantum communication
No full textQuantum technologies have opened new perspectives for enhancing communication speed and security, particularly in challenging underwater environments, where conventional protocols rely on acoustic wave propagation. In this study, we introduce an innovative communication protocol built upon the utilization of mesoscopic twin-beam (TWB) states, entangled in the number of photons, and photon-number-resolving detectors. Our approach involves transmitting information by mixing the part of TWB that propagates through water with two signals having identical mean values but different statistical distributions. Specifically, we explore the advantages and limitations associated with employing pseudothermal states and two distinct types of superthermal states in our communication protocol. Through both theoretical analysis and experimental investigation, we assess the feasibility of accurately discriminating which state has been superimposed onto the TWB by evaluating the noise reduction factor. Our findings demonstrate promis- ing outcomes, suggesting the practical implementation of this protocol in real-world underwater communication scenarios
Towards underwater quantum communication in the mesoscopic intensity regime
Full text linkThe 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
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