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The Fermi gF(x,p) function provides a phase space description of quantum mechanics conceptually different from that based on the the Wigner function W(x,p). In this paper, we show that for a peaked wave packet the gF(x,p)=0 curve approximately corresponds to a phase space contour level of the Wigner function and provides a satisfactory description of the wave packet’s size and shape. Our results show that the Fermi function is an interesting tool to investigate quantum fluctuations in the semiclassical regime. [ABSTRACT FROM AUTHOR]

Starting from the assumption that rod cells are sensitive to single photons, we propose a method to verify the existence of a quantum superposition in the retina, observing the Rabi oscillations in the quantum interaction of a coherent laser light with the rod cells. The computer simulation shows that the oscillations visibility is a robust parameter, so that it would be possible to observe the fringes also in presence of strong decoherence. The feasibility of the experiment is ensured by the new MEA (microelectrode array) technology, that allows to record the transretinal voltage change of a single retinal segment. [ABSTRACT FROM AUTHOR]

We study the stability under quantum noise effects of the quantum privacy amplification protocol for the purification of entanglement in quantum cryptography. We assume that the E91 protocol is used by two communicating parties (Alice and Bob) and that the eavesdropper Eve uses the isotropic Bužek-Hillery quantum copying machine to extract information. Entanglement purification is then operated by Alice and Bob by means of the quantum privacy amplification protocol and we present a systematic numerical study of the impact of all possible single-qubit noise channels on this protocol. We find that both the qualitative behavior of the fidelity of the purified state as a function of the number of purification steps and the maximum level of noise that can be tolerated by the protocol strongly depend on the specific noise channel. These results provide valuable information for experimental implementations of the quantum privacy amplification protocol. [ABSTRACT FROM AUTHOR]

We review the main results obtained recently by our group in the field of quantum noise reduction in nonlinear optical systems. We illustrate the possibility of obtaining significant effects in degenerate parametric oscillators, intracavity second-harmonic generation, nondegenerate four-wave mixing, and one- and two-photon optical bistability. [ABSTRACT FROM AUTHOR]

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Copyright of Il Nuovo Cimento: A is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)