I am full professor of Structure of Matter, Quantum Optics and General Physics at the University “Federico II” of Napoli, since 1991 and author of more than 100 articles on international scientific journals.
Topological insulators are fascinating states of matter exhibiting protected edge states and robu... more Topological insulators are fascinating states of matter exhibiting protected edge states and robust quantized features in their bulk. Here we propose and validate experimentally a method to detect topological properties in the bulk of one-dimensional chiral systems. We first introduce the mean chiral displacement, an observable that rapidly approaches a value proportional to the Zak phase during the free evolution of the system. Then we measure the Zak phase in a photonic quantum walk of twisted photons, by observing the mean chiral displacement in its bulk. Next, we measure the Zak phase in an alternative, inequivalent timeframe and combine the two windings to characterize the full phase diagram of this Floquet system. Finally, we prove the robustness of the measure by introducing dynamical disorder in the system. This detection method is extremely general and readily applicable to all present one-dimensional platforms simulating static or Floquet chiral systems.
The “quantum walk” has emerged recently as a paradigmatic process for the dynamic simulation of c... more The “quantum walk” has emerged recently as a paradigmatic process for the dynamic simulation of complex quantum systems, entanglement production and quantum computation. Hitherto, photonic implementations of quantum walks have mainly been based on multipath interferometric schemes in real space. We report the experimental realization of a discrete quantum walk taking place in the orbital angular momentum space of light, both for a single photon and for two simultaneous photons. In contrast to previous implementations, the whole process develops in a single light beam, with no need of interferometers; it requires optical resources scaling linearly with the number of steps; and it allows flexible control of input and output superposition states. Exploiting the latter property, we explored the system band structure in momentum space and the associated spin-orbit topological features by simulating the quantum dynamics of Gaussian wavepackets. Our demonstration introduces a novel versati...
In this paper we show that an optical setup based on a polarizing Sagnac interferometer combined ... more In this paper we show that an optical setup based on a polarizing Sagnac interferometer combined with a Dove prism can be used as a convenient general-purpose tool for the generation, detection and sorting of spin-orbit states of light. This device can work both in the classical and in the quantum single-photon regime, provides higher sorting efficiency and extinction ratio than usual hologram-fiber combinations, and shows much higher stability and ease of alignment than Mach-Zehnder interferometer setups. To demonstrate the full potential of this setup, we also report some demonstrative experiments of several possible applications of this setup.
The performance of a 20 sq m parabolic cylindrical mirror is described with reference to the opti... more The performance of a 20 sq m parabolic cylindrical mirror is described with reference to the optical properties (concentration ratio, reflection efficiency), to the thermodynamic properties (efficiency obtained in the conversion of solar energy into heat at temperatures in the range 100-350 C) and with reference to applications to a desalting cycle or to the production of mechanical energy.
ABSTRACT The problem of propagation of guided light in hybrid integrated planar waveguides is aff... more ABSTRACT The problem of propagation of guided light in hybrid integrated planar waveguides is afforded in terms of Local Normal Modes. The approach is then generalized taking into account reflected modes arising when index discontinuity between adjacent guiding steps is significant. This is crucial for liquid crystal based waveguide devices. Transmission features in homogeneous as well as inhomogeneous and anisotropic waveguides have been considered in numerical computations. One of the worked examples can well explain previously reported experimental results.
Topological insulators are fascinating states of matter exhibiting protected edge states and robu... more Topological insulators are fascinating states of matter exhibiting protected edge states and robust quantized features in their bulk. Here we propose and validate experimentally a method to detect topological properties in the bulk of one-dimensional chiral systems. We first introduce the mean chiral displacement, an observable that rapidly approaches a value proportional to the Zak phase during the free evolution of the system. Then we measure the Zak phase in a photonic quantum walk of twisted photons, by observing the mean chiral displacement in its bulk. Next, we measure the Zak phase in an alternative, inequivalent timeframe and combine the two windings to characterize the full phase diagram of this Floquet system. Finally, we prove the robustness of the measure by introducing dynamical disorder in the system. This detection method is extremely general and readily applicable to all present one-dimensional platforms simulating static or Floquet chiral systems.
The “quantum walk” has emerged recently as a paradigmatic process for the dynamic simulation of c... more The “quantum walk” has emerged recently as a paradigmatic process for the dynamic simulation of complex quantum systems, entanglement production and quantum computation. Hitherto, photonic implementations of quantum walks have mainly been based on multipath interferometric schemes in real space. We report the experimental realization of a discrete quantum walk taking place in the orbital angular momentum space of light, both for a single photon and for two simultaneous photons. In contrast to previous implementations, the whole process develops in a single light beam, with no need of interferometers; it requires optical resources scaling linearly with the number of steps; and it allows flexible control of input and output superposition states. Exploiting the latter property, we explored the system band structure in momentum space and the associated spin-orbit topological features by simulating the quantum dynamics of Gaussian wavepackets. Our demonstration introduces a novel versati...
In this paper we show that an optical setup based on a polarizing Sagnac interferometer combined ... more In this paper we show that an optical setup based on a polarizing Sagnac interferometer combined with a Dove prism can be used as a convenient general-purpose tool for the generation, detection and sorting of spin-orbit states of light. This device can work both in the classical and in the quantum single-photon regime, provides higher sorting efficiency and extinction ratio than usual hologram-fiber combinations, and shows much higher stability and ease of alignment than Mach-Zehnder interferometer setups. To demonstrate the full potential of this setup, we also report some demonstrative experiments of several possible applications of this setup.
The performance of a 20 sq m parabolic cylindrical mirror is described with reference to the opti... more The performance of a 20 sq m parabolic cylindrical mirror is described with reference to the optical properties (concentration ratio, reflection efficiency), to the thermodynamic properties (efficiency obtained in the conversion of solar energy into heat at temperatures in the range 100-350 C) and with reference to applications to a desalting cycle or to the production of mechanical energy.
ABSTRACT The problem of propagation of guided light in hybrid integrated planar waveguides is aff... more ABSTRACT The problem of propagation of guided light in hybrid integrated planar waveguides is afforded in terms of Local Normal Modes. The approach is then generalized taking into account reflected modes arising when index discontinuity between adjacent guiding steps is significant. This is crucial for liquid crystal based waveguide devices. Transmission features in homogeneous as well as inhomogeneous and anisotropic waveguides have been considered in numerical computations. One of the worked examples can well explain previously reported experimental results.
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