Showing papers by "Filippo Cardano published in 2019"
TL;DR: A bird’s-eye view of the progress of this technology in recent years is presented and some educated guesses on the most likely future developments are offered.
Abstract: Since their first introduction in 2006, q-plates have found a constantly increasing number of uses in diverse contexts, ranging from fundamental research on complex structured light fields to more applicative innovations of established experimental techniques, passing through a variety of other emerging topics, such as, for instance, quantum information protocols based on the angular momentum of light. In this paper, we present a bird’s-eye view of the progress of this technology in recent years and offer some educated guesses on the most likely future developments.
109 citations
TL;DR: In this article, a bipartite continuous-variable Gaussian entangled state with nonzero orbital angular momentum was obtained by using a reconfigurable homodyne detector to retrieve the entire quantum state covariance matrix.
Abstract: The orbital angular momentum of light, unlike spin, is an infinite-dimensional discrete variable and may hence offer enhanced performances for encoding, transmitting, and processing quantum information. Hitherto, this degree of freedom of light has been studied mainly in the context of quantum states with definite number of photons. On the other hand, field-quadrature continuous-variable quantum states of light allow implementing many important quantum protocols not accessible with photon-number states. Here, we realize a scheme based on a $q$-plate device for endowing a bipartite continuous-variable Gaussian entangled state with nonzero orbital angular momentum. We then apply a reconfigurable homodyne detector working directly with such nonzero orbital angular momentum modes in order to retrieve experimentally their entire quantum-state covariance matrix, thus providing a full characterization of their quantum fluctuation properties. Our work is a step towards generating multipartite continuous-variable entanglement in a single optical beam.
12 citations
TL;DR: In this paper, a femtosecond vector vortex beam is generated by means of q-plates with topological charges q = 1, 3/2, 2, 5/2.
11 citations
01 Mar 2019
TL;DR: In this article, the authors apply the concept of digital holography to the study of the orbital angular momentum content of structured light, in particular the interference pattern formed by the light beam under investigation and a reference field is analyzed digitally, and the complete electric field is obtained.
Abstract: Helical modes of light, that is those optical spatial modes carrying a definite amount of orbital angular momentum, are proving a crucial resource in modern photonics. In all applications that rely on these modes and on their combination, a fundamental role is played by the scheme that is used to characterise the complex structure of the light beam. Here we describe a technique that applies the concept of digital holography to the study of the orbital angular momentum content of structured light [1]. In particular, the interference pattern formed by the light beam under investigation and a reference field is analysed digitally, and the complete electric field is obtained. A decomposition in term of helical modes allows one to get the orbital angular momentum spectrum of the beam in a few steps, with the possibility of retrieving also the complex radial profile associated with each mode. Requiring a simple setup and a limited number of measurements, this technique could provide a convenient strategy for the characterisation of structured light beams.
1 citations
11 Oct 2019
TL;DR: In this paper, a hybrid approach realizing bipartite continuous-variable Gaussian entangled state made up of two electromagnetic modes carrying orbital angular momentum is used for endowing a pair of entangled beams with such a degree of freedom.
Abstract: Orbital angular momentum is a discrete degree of freedom that can access an infinite dimensional Hilbert space, thus enhancing the information capacity of a single optical beam. Continuous variables field quadratures allow achieving some quantum tasks in a more advantageous way with respect to the use of photon-number states. Here, we use a hybrid approach realizing bipartite continuous-variable Gaussian entangled state made up of two electromagnetic modes carrying orbital angular momentum. A q-plate is used for endowing a pair of entangled beams with such a degree of freedom. This quantum state is then completely characterized thanks to a novel design of a homodyne detector in which also the local oscillator is an orbital angular momentum-carrying beams so allowing the direct detection of vortex modes quadratures.
1 citations
04 Apr 2019
TL;DR: In this article, a photonic platform allows implementing 2D Quantum Walks in the space of transverse wavevector components of a single light beam, and detection of an anomalous velocity demonstrates that this system simulates a Quantum Hall Insulator.
Abstract: A new photonic platform allows implementing 2D Quantum Walks in the space of transverse wavevector components of a single light beam. Detection of an anomalous velocity demonstrates that this system simulates a Quantum Hall Insulator.
1 citations
04 Apr 2019
TL;DR: In this paper, the authors mimic one dimensional forced quantum walks by using the photonic implementation obtained by means of a sequence of liquid-crystal devices (g-plates) which apply polarization-dependent transverse kicks to the photons in the beam.
Abstract: We mimic one dimensional forced quantum walks by using the photonic implementation obtained by means of a sequence of liquid-crystal devices (”g-plates”), which apply polarization-dependent transverse kicks to the photons in the beam. We observed refocusing phenomena for localized initial states.
09 Jul 2019
TL;DR: This contribution shows how the polarization d.o.m.f. of a pair of entangled modes is coupled to the optical orbital angular momentum giving, at the end, a pairof entangled modes that have orthogonal OAM and polarization.
Abstract: Continuous variable entanglement is usually set between pairs of optical modes sharing the same geometrical property where distinguishability is demanded to polarization and/or frequency. Thus, the inherent non-local correlation shows-up in quantum quadratures relative to two distinct e.m. modes. In this contribution we will show how the polarization d.o.f. of a pair of entangled modes is coupled to the optical orbital angular momentum giving, at the end, a pair of entangled modes that have orthogonal OAM and polarization. We also show how this experimental scheme can be extended to give more than a pair of entangled modes paving the way to CV entanglement multiplexing.