Publications

@article{<LineBreak>	11588_959567,

title = {Reconfigurable homodyne detector for vortex beams},

author = {A. Pecoraro and F. Cardano and L. Marrucci and A. Porzio},

doi = {10.1016/j.physleta.2024.129363},

year  = {2024},

date = {2024-01-01},

urldate = {2024-01-01},

journal = {PHYSICS LETTERS A},

volume = {500},

abstract = {We review the general properties of balanced optical homodyne detectors (BHD) that provide a physical implementation of the quantum field quadrature observable. Then, we discuss the particular case of a BHD designed to span a prescribed sub-space of vortex optical modes carrying orbital angular momentum. By properly tailoring the geometrical features of the local oscillator, mode matching with the signal to be detected is achieved guaranteeing a visibility around 97%. This performance has recently allowed the detection of continuous-variable entanglement between structured modes. Homodyning structured light may pave the way to its use in optical coherent communication and quantum communication protocols.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{	11588_943870,

title = {Waveguiding driven by the Pancharatnam-Berry phase},

author = {Chandroth P. Jisha and Stree Vithya Arumugam and Lorenzo Marrucci and Stefan Nolte and Alessandro Alberucci},

doi = {10.1103/physreva.107.013523},

year  = {2023},

date = {2023-01-01},

journal = {PHYSICAL REVIEW A},

volume = {107},

number = {1},

abstract = {We theoretically and numerically investigate the properties of waveguides based on the Pancharatnam-Berry phase, obtained by a longitudinally periodic rotation of the optic axis in a transversely twisted birefringent medium. In this paper we study the case where the period of the longitudinal modulation is chosen so that a net accumulation of geometric phase in propagation occurs. First, the interplay between different contributions to the optical potential is addressed. Second, a continuous evolution of the polarization structure of the quasimodes is observed in the numerical simulations. We explain it by a combination of plane-wave-based models and gauge transformations. We discover that, beyond the longitudinal oscillations, the polarization of the quasimode also varies through its cross section. The analogies with respect to charged particles moving in a magnetic field are outlined.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{11588_916341,

title = {Electric polarization and its quantization in one-dimensional non-Hermitian chains},

author = {Hu Jinbing and Carmine Antonio Perroni and Giulio De Filippis and Songlin Zhuang and Lorenzo Marrucci and Filippo Cardano},

doi = {10.1103/PhysRevB.107.L121101},

year  = {2023},

date = {2023-01-01},

urldate = {2023-01-01},

journal = {PHYSICAL REVIEW. B},

volume = {107},

number = {12},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{11588_943879,

title = {Generation of high-dimensional qudit quantum states via two-dimensional quantum walks},

author = {Chiara Esposito and Francesco Di Colandrea and Francesco Hoch and Gonzalo Carvacho and Filippo Cardano and Nicolò Spagnolo and Lorenzo Marrucci and Fabio Sciarrino},

doi = {10.1103/PhysRevResearch.5.043025},

year  = {2023},

date = {2023-01-01},

urldate = {2023-01-01},

journal = {PHYSICAL REVIEW RESEARCH},

volume = {5},

number = {4},

abstract = {Several quantum protocols, with applications ranging from fundamental studies to cryptographic scenarios, can be enhanced through the generation and manipulation of quantum states that belong to high-dimensional Hilbert spaces. For this reason, it is worth devoting efforts to find more efficient methods for complex qudit-state generation. One-dimensional quantum walks have proved to be efficient and versatile platforms for the engineering of such complex states. Hitherto, however, using their two-dimensional counterpart for this task has remained unexplored. In this paper, we consider two-dimensional quantum walk evolution as a tool for the generation of high-dimensional qudit states. We theoretically prove that a suitable change of the coin operators at each step permits the generation of a subset of qudit states by using less resources with respect to the one-dimensional counterpart. Then, we successfully generate qudit states by exploiting two-dimensional quantum walks on an experimental photonic platform. The walker position is encoded on discrete sets of optical modes carrying quantized amounts of transverse momentum and the mode couplings are actively controlled via liquid-crystal devices. The obtained results provide insight into qudit generation for applications in quantum communication and quantum cryptography.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{11588_921728,

title = {Ultra-long quantum walks via spin-orbit photonics},

author = {Francesco Di Colandrea and Amin Babazadeh and Alexandre Dauphin and Pietro Massignan and Lorenzo Marrucci and Filippo Cardano},

doi = {10.1364/optica.474542},

year  = {2023},

date = {2023-01-01},

urldate = {2023-01-01},

journal = {OPTICA},

volume = {10},

number = {3},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{	11588_943876,

title = {Orbital angular momentum based intra- and interparticle entangled states generated via a quantum dot source},

author = {Alessia Suprano and Danilo Zia and Mathias Pont and Taira Giordani and Giovanni Rodari and Mauro Valeri and Bruno Piccirillo and Gonzalo Carvacho and Nicolò Spagnolo and Pascale Senellart and Lorenzo Marrucci and Fabio Sciarrino},

doi = {10.1117/1.AP.5.4.046008},

year  = {2023},

date = {2023-01-01},

journal = {ADVANCED PHOTONICS},

volume = {5},

number = {04},

abstract = {Engineering single-photon states endowed with orbital angular momentum (OAM) is a powerful tool for quantum information photonic implementations. Indeed, due to its unbounded nature, OAM is suitable for encoding qudits, allowing a single carrier to transport a large amount of information. Most of the experimental platforms employ spontaneous parametric down-conversion processes to generate single photons, even if this approach is intrinsically probabilistic, leading to scalability issues for an increasing number of qudits. Semiconductor quantum dots (QDs) have been used to get over these limitations by producing on- demand pure and indistinguishable single-photon states, although only recently they have been exploited to create OAM modes. Our work employs a bright QD single-photon source to generate a complete set of quantum states for information processing with OAM-endowed photons. We first study hybrid intraparticle entanglement between OAM and polarization degrees of freedom of a single photon whose preparation was certified by means of Hong–Ou–Mandel visibility. Then, we investigate hybrid interparticle OAM- based entanglement by exploiting a probabilistic entangling gate. The performance of our approach is assessed by performing quantum state tomography and violating Bell inequalities. Our results pave the way for the use of deterministic sources for the on-demand generation of photonic high-dimensional quantum states.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{<LineBreak>	11588_943878,

title = {Roadmap on structured waves},

author = {K. Y. Bliokh and E. Karimi and M. J. Padgett and M. A. Alonso and M. R. Dennis and A. Dudley and A. Forbes and S. Zahedpour and S. W. Hancock and H. M. Milchberg and S. Rotter and F. Nori and S. K. Ozdemir and N. Bender and H. Cao and P. B. Corkum and C. Hernandez-Garcia and H. Ren and Y. Kivshar and M. G. Silveirinha and N. Engheta and A. Rauschenbeutel and P. Schneeweiss and J. Volz and D. Leykam and D. A. Smirnova and K. Rong and B. Wang and E. Hasman and M. F. Picardi and A. V. Zayats and F. J. Rodriguez-Fortuno and C. Yang and J. Ren and A. B. Khanikaev and A. Alu and E. Brasselet and M. Shats and J. Verbeeck and P. Schattschneider and D. Sarenac and D. G. Cory and D. A. Pushin and M. Birk and A. Gorlach and I. Kaminer and F. Cardano and L. Marrucci and M. Krenn and F. Marquardt},

doi = {10.1088/2040-8986/acea92},

year  = {2023},

date = {2023-01-01},

urldate = {2023-01-01},

journal = {JOURNAL OF OPTICS},

volume = {25},

number = {10},

abstract = {Structured waves are ubiquitous for all areas of wave physics, both classical and quantum, where the wavefields are inhomogeneous and cannot be approximated by a single plane wave. Even the interference of two plane waves, or of a single inhomogeneous (evanescent) wave, provides a number of nontrivial phenomena and additional functionalities as compared to a single plane wave. Complex wavefields with inhomogeneities in the amplitude, phase, and polarization, including topological structures and singularities, underpin modern nanooptics and photonics, yet they are equally important, e.g. for quantum matter waves, acoustics, water waves, etc. Structured waves are crucial in optical and electron microscopy, wave propagation and scattering, imaging, communications, quantum optics, topological and non-Hermitian wave systems, quantum condensed-matter systems, optomechanics, plasmonics and metamaterials, optical and acoustic manipulation, and so forth. This Roadmap is written collectively by prominent researchers and aims to survey the role of structured waves in various areas of wave physics. Providing background, current research, and anticipating future developments, it will be of interest to a wide cross-disciplinary audience.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{	11588_943872,

title = {Spatial mode analysis of optical beams carrying monstar disclinations},

author = {V. Vicuna-Hernandez and F. Cardano and P. Darvehi and L. Marrucci and A. Rubano and B. Piccirillo},

doi = {10.1088/2040-8986/acbce3},

year  = {2023},

date = {2023-01-01},

journal = {JOURNAL OF OPTICS},

volume = {25},

number = {4},

abstract = {Asymmetric polarization disclinations, such as monstars, can be generated in two distinct ways: (a) by an inseparable superposition of three spatial modes bearing optical vortices with circular polarization states; (b) by using a modulated Poincaré beam, consisting of an inseparable superposition of a circularly-polarized fundamental Gaussian beam TEM00 and a second beam exhibiting an azimuthally-modulated vortex with an m-fold rotational symmetry and the opposite circular polarization. Based on the analysis of the spatial modes indirectly involved into the superposition through the latter method, we investigate its capability of spanning as many disclinations as possible, as well as its capability of enabling effective predictions about the generated patterns, such as relevant geometric features, already at the design stage.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{11588_947884,

title = {Exploring the impact of longitudinal modulation on the twisting angle in Pancharatnam-Berry phase-based waveguides},

author = {Stree Vithya Arumugam and Chandroth P. Jisha and Lorenzo Marrucci and Alessandro Alberucci and Stefan Nolte},

doi = {10.1364/OE.505538},

year  = {2023},

date = {2023-01-01},

urldate = {2023-01-01},

journal = {OPTICS EXPRESS},

volume = {31},

number = {26},

pages = {44283–44294},

abstract = {A circularly polarized (CP) beam propagating in a rotated anisotropic material acquires an additional phase delay proportional to the local rotation angle. This phase delay is a particular kind of geometric phase, the Pancharatnam-Berry phase (PBP), stemming from the path of the beam polarization on the Poincaré sphere. A transverse gradient in the geometric phase can thus be imparted by inhomogeneous rotation of the material, with no transverse gradient in the dynamic phase. A waveguide based upon this principle can be induced when the gradient accumulates in propagation, the latter requiring a longitudinal rotation in the optic axis synchronized with the natural rotation of the light polarization. Here, we evaluate numerically and theoretically the robustness of PBP-based waveguides, in the presence of a mismatch between the birefringence length and the external modulation. We find that the mismatch affects mainly the polarization of the quasi-mode, while the confinement is only slightly perturbed.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{	11588_943874,

title = {Twisted photons: what is the orbital angular momentum of light?},

author = {Filippo Cardano and Lorenzo Marrucci},

doi = {10.1051/photon/202311962},

year  = {2023},

date = {2023-01-01},

journal = {PHOTONIQUES},

volume = {119},

pages = {62–66},

abstract = {In this introductory article, we explain the concept of orbital angular momentum (OAM) of light, discussing its physical meaning and its relationship with the more familiar spin angular momentum of circularly polarized waves. We address both classical and quantum aspects, emphasizing the distinction between OAM eigenstates – helical waves – and the general case. Finally, we briefly touch upon the main optical techniques to generate these optical states and emerging applications in the field.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{	11588_867677,

title = {Linking topological features of the Hofstadter model to optical diffraction figures},

author = {Francesco Di Colandrea and Alessio D’Errico and Maria Maffei and Hannah M Price and Maciej Lewenstein and Lorenzo Marrucci and Filippo Cardano and Alexandre Dauphin and Pietro Massignan},

doi = {10.1088/1367-2630/ac4126},

year  = {2022},

date = {2022-01-01},

journal = {NEW JOURNAL OF PHYSICS},

volume = {24},

number = {1},

abstract = {In two, three and even four spatial dimensions, the transverse responses experienced by a charged particle on a lattice in a uniform magnetic field are fully controlled by topological invariants called Chern numbers, which characterize the energy bands of the underlying Hofstadter Hamiltonian. These remarkable features, solely arising from the magnetic translational symmetry, are captured by Diophantine equations which relate the fraction of occupied states, the magnetic flux and the Chern numbers of the system bands. Here we investigate the close analogy between the topological properties of Hofstadter Hamiltonians and the diffraction figures resulting from optical gratings. In particular, we show that there is a one-to-one relation between the above mentioned Diophantine equation and the Bragg condition determining the far-field positions of the optical diffraction peaks. As an interesting consequence of this mapping, we discuss how the robustness of diffraction figures to structural disorder in the grating is a direct analogue of the robustness of transverse conductance in the quantum Hall effect.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{	11588_943869,

title = {Smoke rings of light},

author = {F. Cardano and L. Marrucci},

doi = {10.1038/s41566-022-01032-9},

year  = {2022},

date = {2022-01-01},

journal = {NATURE PHOTONICS},

volume = {16},

number = {7},

pages = {476–477},

abstract = {The ability to create complex three-dimensional structures of light has reached new heights with the experimental observation of two distinct kinds of toroidal pulses, the optical analogue of smoke rings.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{	11588_880120,

title = {Quantum walks of two correlated photons in a 2D synthetic lattice},

author = {Chiara Esposito and Mariana R. Barros and Andrés Durán Hernández and Gonzalo Carvacho and Francesco Di Colandrea and Raouf Barboza and Filippo Cardano and Nicolò Spagnolo and Lorenzo Marrucci and Fabio Sciarrino},

url = {https://doi.org/10.1038/s41534-022-00544-0},

doi = {10.1038/s41534-022-00544-0},

year  = {2022},

date = {2022-01-01},

journal = {NPJ QUANTUM INFORMATION},

volume = {8},

number = {1},

abstract = {Quantum walks represent paradigmatic quantum evolutions, enabling powerful applications in the context of topological physics and quantum computation. They have been implemented in diverse photonic architectures, but the realization of two-particle dynamics on a multidimensional lattice has hitherto been limited to continuous-time evolutions. To fully exploit the computational capabilities of quantum interference it is crucial to develop platforms handling multiple photons that propagate across multidimensional lattices. Here, we report a discrete-time quantum walk of two correlated photons in a two-dimensional lattice, synthetically engineered by manipulating a set of optical modes carrying quantized amounts of transverse momentum. Mode-couplings are introduced via the polarization-controlled diffractive action of thin geometric-phase optical elements. The entire platform is compact, efficient, scalable, and represents a versatile tool to simulate quantum evolutions on complex lattices. We expect that it will have a strong impact on diverse fields such as quantum state engineering, topological quantum photonics, and Boson Sampling.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{	11588_877128,

title = {Ultra-sensitive measurement of transverse displacements with linear photonic gears},

author = {Raouf Barboza and Amin Babazadeh and Lorenzo Marrucci and Filippo Cardano and Corrado Lisio and Vincenzo D’Ambrosio},

doi = {10.1038/s41467-022-28700-2},

year  = {2022},

date = {2022-01-01},

journal = {NATURE COMMUNICATIONS},

volume = {13},

number = {1},

abstract = {Accurately measuring mechanical displacements is essential for a vast portion of current technologies. Several optical techniques accomplish this task, allowing for non-contact sensing even below the diffraction limit. Here we introduce an optical encoding technique, dubbed “linear photonic gears”, that enables ultra-sensitive measurements of a transverse displacement by mapping it into the polarization rotation of a laser beam. In ordinary ambient conditions, we measure the relative shift between two objects with a resolution of 400 pm. We argue that a resolution of 50 pm should be achievable with existing state-of-the-art technologies. Our single-optical-path scheme is intrinsically stable and it could be implemented as a compact sensor, using cost effective integrated optics. We anticipate it may have a strong impact on both research and industry.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{	11588_838662,

title = {Longitudinal fields and transverse rotations},

author = {F. Cardano and L. Marrucci},

doi = {10.1038/s41566-020-00756-w},

year  = {2021},

date = {2021-01-01},

journal = {NATURE PHOTONICS},

volume = {15},

number = {2},

pages = {72–74},

abstract = {Electromagnetic fields in light waves are mainly transverse to propagation direction but actually also have longitudinal components, which may give rise to unexpected optical phenomena involving the angular momentum of light, such as transverse spin and optical torques.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{	11588_850815,

title = {Increasing the topological diversity of light with modulated Poincaré beams},

author = {Pegah Darvehi and Verónica Vicuña-Hernández and Lorenzo Marrucci and Ester Piedipalumbo and Enrico Santamato and Bruno Piccirillo},

doi = {10.1088/2040-8986/abf293},

year  = {2021},

date = {2021-01-01},

journal = {JOURNAL OF OPTICS},

volume = {23},

number = {5},

abstract = {We introduce a wide class of singular inhomogeneously polarized beams characterized by a nonuniform rotation rate of the local polarization azimuth about a C- or a V-point. They are obtained by adding an extra phase modulation with an m-fold rotational symmetry to the helical wavefronts underpinning Poincaré beams. The resulting modulated Poincaré beams have been theoretically studied and experimentally generated using tailored space-varying-axis plates based on liquid crystals.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{	11588_841962,

title = {Bloch–Landau–Zener dynamics induced by a synthetic field in a photonic quantum walk},

author = {Alessio D’Errico and Raouf Barboza and Rebeca Tudor and Alexandre Dauphin and Pietro Massignan and Lorenzo Marrucci and Filippo Cardano},

doi = {10.1063/5.0037327},

year  = {2021},

date = {2021-01-01},

journal = {APL PHOTONICS},

volume = {6},

number = {2},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{	11588_787881,

title = {Two-dimensional topological quantum walks in the momentum space of structured light},

author = {Alessio D’Errico and Filippo Cardano and Maria Maffei and Alexandre Dauphin and Raouf Barboza and Chiara Esposito and Bruno Piccirillo and Maciej Lewenstein and Pietro Massignan and Lorenzo Marrucci},

doi = {10.1364/OPTICA.365028},

year  = {2020},

date = {2020-01-01},

journal = {OPTICA},

volume = {7},

number = {2},

abstract = {Quantum walks are powerful tools for quantum applications and for designing topological systems. Although they are simulated in a variety of platforms, genuine two-dimensional realizations are still challenging. Here we present an inno- vative approach to the photonic simulation of a quantum walk in two dimensions, where walker positions are encoded in the transverse-wavevector component of a single light beam. The desired dynamics is obtained by means of a sequence of liquid-crystal devices, which apply polarization-dependent transverse “kicks” to the photons in the beam. We engineer our quantum walk so that it realizes a periodically driven Chern insulator, and we probe its topological features by detect- ing the anomalous displacement of the photonic wavepacket under the effect of a constant force. Our compact, versatile platform offers exciting prospects for the photonic simulation of two-dimensional quantum dynamics and topological systems.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{	11588_826773,

title = {Hyperentanglement in structured quantum light},

author = {Francesco Graffitti and Vincenzo D'Ambrosio and Massimiliano Proietti and Ho Joseph and Bruno Piccirillo and Corrado Lisio and Lorenzo Marrucci and Alessandro Fedrizzi},

doi = {10.1103/PhysRevResearch.2.043350},

year  = {2020},

date = {2020-01-01},

journal = {PHYSICAL REVIEW RESEARCH},

volume = {2},

number = {4},

abstract = {Entanglement in high-dimensional quantum systems, where one or more degrees of freedom of light are involved, offers increased information capacities and enables new quantum protocols. Here, we demonstrate a functional source of high-dimensional, noise-resilient hyperentangled states encoded in time-frequency and vector vortex structured modes, which in turn carry single-particle entanglement between polarization and orbital angular momentum. Pairing nonlinearity-engineered parametric downconversion in an interferometric scheme with spin-to-orbital-angular-momentum conversion, we generate highly entangled photon pairs at telecom wave- length that we characterize via two-photon interference and quantum state tomography, achieving near-unity visibilities and fidelities. While hyperentanglement has been demonstrated before in photonic qubits, here we present a rich entanglement structure involving spectrally and spatially structured light, where three different forms of entanglement coexist in the same biphoton state.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{	11588_805257,

title = {Bulk detection of time-dependent topological transitions in quenched chiral models},

author = {Alessio D'Errico and Francesco Di Colandrea and Raouf Barboza and Alexandre Dauphin and Maciej Lewenstein and Pietro Massignan and Lorenzo Marrucci and Filippo Cardano},

doi = {10.1103/PhysRevResearch.2.023119},

year  = {2020},

date = {2020-01-01},

journal = {PHYSICAL REVIEW RESEARCH},

volume = {2},

number = {2},

abstract = {The topology of one-dimensional chiral systems is captured by the winding number of the Hamiltonian eigenstates. Here we show that this invariant can be read out by measuring the mean chiral displacement of a single-particle wave function that is connected to a fully localized one via a unitary and translation-invariant map. Remarkably, this implies that the mean chiral displacement can detect the winding number even when the underlying Hamiltonian is quenched between different topological phases. We confirm experimentally these results in a quantum walk of structured light.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{	11588_757176,

title = {Continuous-variable entangled states of light carrying orbital angular momentum},

author = {A. Pecoraro and F. Cardano and L. Marrucci and A. Porzio},

doi = {10.1103/PhysRevA.100.012321},

year  = {2019},

date = {2019-01-01},

journal = {PHYSICAL REVIEW A},

volume = {100},

number = {1},

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.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{	11588_753405,

title = {A versatile quantum walk resonator with bright classical light},

author = {Bereneice Sephton and Angela Dudley and Gianluca Ruffato and Filippo Romanato and Lorenzo Marrucci and Miles Padgett and Sandeep Goyal and Filippus Roux and Thomas Konrad and Andrew Forbes},

doi = {10.1371/journal.pone.0214891},

year  = {2019},

date = {2019-01-01},

journal = {PLOS ONE},

volume = {14},

number = {4},

abstract = {In a Quantum Walk (QW) the "walker" follows all possible paths at once through the principle of quantum superposition, differentiating itself from classical random walks where one random path is taken at a time. This facilitates the searching of problem solution spaces faster than with classical random walks, and holds promise for advances in dynamical quantum simulation, biological process modelling and quantum computation. Here we employ a versatile and scalable resonator configuration to realise quantum walks with bright classical light. We experimentally demonstrate the versatility of our approach by implementing a variety of QWs, all with the same experimental platform, while the use of a resonator allows for an arbitrary number of steps without scaling the number of optics. This paves the way for future QW implementations with spatial modes of light in free-space that are both versatile and scalable.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{	11588_757174,

title = {Multi-twist polarization ribbon topologies in highly-confined optical fields},

author = {Thomas Bauer and Peter Banzer and Frédéric Bouchard and Sergej Orlov and Lorenzo Marrucci and Enrico Santamato and Robert W Boyd and Ebrahim Karimi and Gerd Leuchs},

doi = {10.1088/1367-2630/ab171b},

year  = {2019},

date = {2019-01-01},

journal = {NEW JOURNAL OF PHYSICS},

volume = {21},

number = {5},

abstract = {Electromagnetic plane waves, solutions to Maxwell’s equations, are said to be ‘transverse’ in vacuum. Namely, the waves’ oscillatory electric and magnetic fields are confined within a plane transverse to the waves’ propagation direction. Under tight-focusing conditions however, the field can exhibit longitudinal electric or magnetic components, transverse spin angular momentum, or non-trivial topologies such as Möbius strips. Here, we show that when a suitably spatially structured beam is tightly focused, a three-dimensional polarization topology in the form of a ribbon with two full twists appears in the focal volume. We study experimentally the stability and dynamics of the observed polarization ribbon by exploring its topological structure for various radii upon focusing and for different propagation planes.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{	11588_747520,

title = {Shearing interferometry via geometric phase},

author = {Luis A. Alemán-Castaneda and Bruno Piccirillo and Enrico Santamato and Lorenzo Marrucci and Miguel A. Alonso},

doi = {10.1364/OPTICA.6.000396},

year  = {2019},

date = {2019-01-01},

journal = {OPTICA},

volume = {6},

number = {4},

abstract = {We propose an approach based on geometric phase for per- forming several types of shearing interferometry through a robust, compact, common-path setup. The key elements are two identical parallel plates with spatially varying birefringence distributions, which perform the shearing by writing opposite geometric phases on the two circular polarization components of the linearly polarized incident wavefront. This setup allows the independent control of the shearing magnitude and relative phase of the two wavefront replicas. The approach is first illustrated for the simplest case of lateral shearing, and then extended to other geometries where the magnitude and direction of the shear vary smoothly over the wavefront.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{	11588_726351,

title = {Vector vortex beams generated by q-plates as a versatile route to direct fs laser surface structuring},

author = {Jijil JJ Nivas and Elaheh Allahyari and Filippo Cardano and Andrea Rubano and Rosalba Fittipaldi and Antonio Vecchione and Domenico Paparo and Lorenzo Marrucci and Riccardo Bruzzese and Salvatore Amoruso},

url = {http://www.journals.elsevier.com/applied-surface-science/},

doi = {10.1016/j.apsusc.2018.12.091},

year  = {2019},

date = {2019-01-01},

journal = {APPLIED SURFACE SCIENCE},

volume = {471},

pages = {1028–1033},

abstract = {We report an experimental investigation on direct laser surface structuring with femtosecond vector vortex beams generated by means of q-plates with topological charges q = 1, 3/2, 2, 5/2. Structured light beams with spatially variant state of polarization and intensity are generated and applied to multi-pulse irradiation of a solid crystalline silicon target. The creation of a variety of surface structures, like laser induced periodic surface structures, multi-spot arrays and shaped ablation craters, is demonstrated by direct laser surface structuring with vector vortex beams at different values of q. The features of the surface structures are compared with the vector vortex beam characteristics at the focal plane, evidencing their relationship with the polarization and intensity profile of the laser beams. Our experimental findings show that vector vortex beams produced by q-plates can offer a valuable and versatile route to imprint unconventional surface structures on a solid target through a mask-free ablative process and step scan processing.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{	11588_729135,

title = {Experimental Engineering of Arbitrary Qudit States with Discrete-Time Quantum Walks},

author = {Taira Giordani and Emanuele Polino and Sabrina Emiliani and Alessia Suprano and Luca Innocenti and Helena Majury and Lorenzo Marrucci and Mauro Paternostro and Alessandro Ferraro and Nicolò Spagnolo and Fabio Sciarrino},

doi = {10.1103/PhysRevLett.122.020503},

year  = {2019},

date = {2019-01-01},

journal = {PHYSICAL REVIEW LETTERS},

volume = {122},

number = {2},

abstract = {The capability to generate and manipulate quantum states in high-dimensional Hilbert spaces is a crucial step for the development of quantum technologies, from quantum communication to quantum computation. One-dimensional quantum walk dynamics represents a valid tool in the task of engineering arbitrary quantum states. Here we affirm such potential in a linear-optics platform that realizes discrete-time quantum walks in the orbital angular momentum degree of freedom of photons. Different classes of relevant qudit states in a six-dimensional space are prepared and measured, confirming the feasibility of the protocol. Our results represent a further investigation of quantum walk dynamics in photonics platforms, paving the way for the use of such a quantum state-engineering toolbox for a large range of applications.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{	11588_764674,

title = {Electrically tunable vector vortex coronagraphs based on liquid-crystal geometric phase waveplates},

author = {Bruno Piccirillo and Ester Piedipalumbo and Lorenzo Marrucci and Enrico Santamato},

url = {http://www.tandfonline.com/toc/gmcl20/current},

doi = {10.1080/15421406.2019.1581707},

year  = {2019},

date = {2019-01-01},

journal = {MOLECULAR CRYSTALS AND LIQUID CRYSTALS},

volume = {684},

number = {1},

pages = {15–23},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{	11588_727566,

title = {Tunable Two-Photon Quantum Interference of Structured Light},

author = {Vincenzo D’Ambrosio and Gonzalo Carvacho and Iris Agresti and Lorenzo Marrucci and Fabio Sciarrino},

doi = {10.1103/PhysRevLett.122.013601},

year  = {2019},

date = {2019-01-01},

journal = {PHYSICAL REVIEW LETTERS},

volume = {122},

number = {1},

abstract = {Structured photons are nowadays an important resource in classical and quantum optics due to the richness of properties they show under propagation, focusing, and in their interaction with matter. Vectorial modes of light in particular, a class of modes where the polarization varies across the beam profile, have already been used in several areas ranging from microscopy to quantum information. One of the key ingredients needed to exploit the full potential of complex light in the quantum domain is the control of quantum interference, a crucial resource in fields like quantum communication, sensing, and metrology. Here we report a tunable Hong-Ou-Mandel interference between vectorial modes of light. We demonstrate how a properly designed spin-orbit device can be used to control quantum interference between vectorial modes of light by simply adjusting the device parameters and no need of interferometric setups. We believe our result can find applications in fundamental research and quantum technologies based on structured light by providing a new tool to control quantum interference in a compact, efficient, and robust way.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{	11588_742902,

title = {Q-plate technology: a progress review},

author = {Andrea Rubano and Filippo Cardano and Bruno Piccirillo and Lorenzo Marrucci},

doi = {10.1364/JOSAB.36.000D70},

year  = {2019},

date = {2019-01-01},

journal = {JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. B, OPTICAL PHYSICS},

volume = {36},

number = {5},

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.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{	11588_764206,

title = {Enhanced spin orbit interaction of light in highly confining optical fibers for mode division multiplexing},

author = {P Gregg and P Kristensen and A Rubano and S Golowich and L Marrucci and S Ramachandran},

doi = {10.1038/s41467-019-12401-4},

year  = {2019},

date = {2019-01-01},

journal = {NATURE COMMUNICATIONS},

volume = {10},

number = {1},

abstract = {Light carries both orbital angular momentum (OAM) and spin angular momentum (SAM), related to wavefront rotation and polarization, respectively. These are usually approximately independent quantities, but they become coupled by light's spin-orbit interaction (SOI) in certain exotic geometries and at the nanoscale. Here we reveal a manifestation of strong SOI in fibers engineered at the micro-scale and supporting the only known example of propagating light modes with non-integer mean OAM. This enables propagation of a record number (24) of states in a single optical fiber with low cross-talk (purity > 93%), even as tens-of-meters long fibers are bent, twisted or otherwise handled, as fibers are practically deployed. In addition to enabling the investigation of novel SOI effects, these light states represent the first ensemble with which mode count can be potentially arbitrarily scaled to satisfy the exponentially growing demands of high-performance data centers and supercomputers, or telecommunications network nodes.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{	11588_757178,

title = {Terahertz Hyper-Raman Time-Domain Spectroscopy},

author = {A. Rubano and S. Mou and L. Marrucci and D. Paparo},

url = {http://pubs.acs.org/journal/apchd5},

doi = {10.1021/acsphotonics.9b00265},

year  = {2019},

date = {2019-01-01},

journal = {ACS PHOTONICS},

volume = {6},

number = {6},

pages = {1515–1523},

abstract = {A new spectroscopic method has been demonstrated on the benchmark crystal α-SiO2. The new technique makes use of femtosecond optical pulses and intense, sub-ps, broadband terahertz (THz) pulses to generate a THz-optical four wave mixing in the investigated material. The spectrum of the generated signal is resolved in wavelength and displays two pronounced frequency sidebands close to the optical second harmonic central frequency 2ωL, where ωL is the optical central frequency of the fundamental beam. The two sidebands develop around the central frequency at the (anti-) Stokes side of ωs;a = 2ωL ∓ ωT, where ωT is the THz central frequency, thus resembling the spectrum of standard hyper-Raman scattering, and hence, we named this effect “THz Hyper-Raman” - THYR. Due to the large laser and THz bandwidths, it is not possible to resolve the THYR signal in the frequency domain. Nonetheless, by taking advantage of the same principle at work in THz time-domain spectroscopy, it is possible to follow the evolution of the THYR signal in time and access the frequency domain again by Fourier Transform. In this way we were able to observe pronounced oscillations in time of the THYR signal whose frequencies correspond to a large variety of material excitations including Γ-point phonons, polaritons, and phonons out of the Γ-point, which are usually observed only by neutron scattering techniques. To complement the richness of these observations, we will show that the selection rules of the THYR process allow the simultaneous observation of both IR- and Raman-active material modes, thus highlighting the potential of this innovative experimental method.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{	11588_724109,

title = {Symmetry Protection of Photonic Entanglement in the Interaction with a Single Nanoaperture},

author = {Alexander Büse and Mathieu L. Juan and Nora Tischler and Vincenzo D'Ambrosio and Fabio Sciarrino and Lorenzo Marrucci and Gabriel Molina-Terriza},

doi = {10.1103/PhysRevLett.121.173901},

year  = {2018},

date = {2018-01-01},

journal = {PHYSICAL REVIEW LETTERS},

volume = {121},

number = {17},

abstract = {In this work, we experimentally show that quantum entanglement can be symmetry protected in the interaction with a single subwavelength plasmonic nanoaperture, with a total volume of V ∼ 0.2λ^3. In particular, we experimentally demonstrate that two-photon entanglement can be either completely preserved or completely lost after the interaction with the nanoaperture, solely depending on the relative phase between the quantum states. We achieve this effect by using specially engineered two-photon states to match the properties of the nanoaperture. In this way we can access a symmetry protected state, i.e., a state constrained by the geometry of the interaction to retain its entanglement. In spite of the small volume of interaction, we show that the symmetry protected entangled state retains its main properties. This connection between nanophotonics and quantum optics probes the fundamental limits of the phenomenon of quantum interference.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{	11588_718578,

title = {Simple method for the characterization of intense Laguerre-Gauss vector vortex beams},

author = {E. Allahyari and J. Jj Nivas and F. Cardano and R. Bruzzese and R. Fittipaldi and L. Marrucci and D. Paparo and A. Rubano and A. Vecchione and S. Amoruso},

url = {http://scitation.aip.org/content/aip/journal/apl},

doi = {10.1063/1.5027661},

year  = {2018},

date = {2018-01-01},

journal = {APPLIED PHYSICS LETTERS},

volume = {112},

number = {21},

abstract = {We report on a method for the characterization of intense, structured optical fields through the analysis of the size and surface structures formed inside the annular ablation crater created on the target surface. In particular, we apply the technique to laser ablation of crystalline silicon induced by femtosecond vector vortex beams. We show that a rapid direct estimate of the beam waist parameter is obtained through a measure of the crater radii. The variation of the internal and external radii of the annular crater as a function of the laser pulse energy, at fixed number of pulses, provides another way to evaluate the beam spot size through numerical fitting of the obtained experimental data points. A reliable estimate of the spot size is of paramount importance to investigate pulsed laser-induced effects on the target material. Our experimental findings offer a facile way to characterize focused, high intensity complex optical vector beams which are more and more applied in laser-matter interaction experiments.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{	11588_721695,

title = {Surface structures with unconventional patterns and shapes generated by femtosecond structured light fields},

author = {Jijil Jj Nivas and Elaheh Allahyari and Filippo Cardano and Andrea Rubano and Rosalba Fittipaldi and Antonio Vecchione and Domenico Paparo and Lorenzo Marrucci and Riccardo Bruzzese and Salvatore Amoruso},

doi = {10.1038/s41598-018-31768-w},

year  = {2018},

date = {2018-01-01},

journal = {SCIENTIFIC REPORTS},

volume = {8},

number = {1},

abstract = {We present an investigation on ultrashort laser surface structuring with structured light fields generated by various q-plates. In particular, q-plates with topological charges q = 1, 3/2, 2, 5/2 are used to generate femtosecond (fs) vector vortex beams, and form complex periodic surface structures through multi-pulse ablation of a solid crystalline silicon target. We show how optical retardation tuning of the q-plate offers a feasible way to vary the fluence transverse distribution of the beam, thus allowing the production of structures with peculiar shapes, which depend on the value of q. The features of the generated surface structures are compared with the vector vortex beam characteristics at the focal plane, by rationalizing their relationship with the local state of the laser light. Our experimental findings demonstrate how irradiation with fs complex light beams can offer a valuable route to design unconventional surface structures.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{	11588_698314,

title = {Ultrafast modification of the polarity at LaAlO3/SrTiO3 interfaces},

author = {A. Rubano and T. Günter and M. Fiebig and F. Miletto Granozio and L. Marrucci and D. Paparo},

url = {http://harvest.aps.org/v2/bagit/articles/10.1103/PhysRevB.97.035438/apsxml},

doi = {10.1103/PhysRevB.97.035438},

year  = {2018},

date = {2018-01-01},

journal = {PHYSICAL REVIEW. B},

volume = {97},

number = {3},

abstract = {Oxide growth with semiconductorlike accuracy has led to atomically precise thin films and interfaces that exhibit a plethora of phases and functionalities not found in the oxide bulk material. This has yielded spectacular discoveries such as the conducting, magnetic, and even superconducting LaAlO3/SrTiO3 interfaces separating two prototypical insulating perovskite materials. All these investigations, however, consider the static state at the interface, although studies on fast oxide interface dynamics would introduce a powerful degree of freedom to understanding the nature of the LaAlO3/SrTiO3 interface state. Here, we show that the polarization state at the LaAlO3/SrTiO3 interface can be optically enhanced or attenuated within picoseconds. Our observations are explained by a model based on charge propagation effects in the interfacial vicinity and transient polarization buildup at the interface.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{	11588_719905,

title = {12 mode, WDM, MIMO-free orbital angular momentum transmission},

author = {Kasper Ingerslev and Patrick Gregg and Michael Galili and Francesco Da Ros and Hu Hao and Fangdi Bao and Mario A. Usuga Castaneda and Poul Kristensen and Andrea Rubano and Lorenzo Marrucci and Karsten Rottwitt and Toshio Morioka and Siddharth Ramachandran and Leif Katsuo Oxenløwe},

doi = {10.1364/OE.26.020225},

year  = {2018},

date = {2018-01-01},

journal = {OPTICS EXPRESS},

volume = {26},

number = {16},

abstract = {Simultaneous MIMO-free transmission of 12 orbital angular momentum (OAM) modes over a 1.2 km air-core fiber is demonstrated. WDM compatibility of the system is shown by using 60, 25 GHz spaced WDM channels with 10 GBaud QPSK signals. System performance is evaluated by measuring bit error rates, which are found to be below the soft FEC limit, and limited by inter-modal crosstalk. The crosstalk in the system is analyzed, and it is concluded that it can be significantly reduced with an improved multiplexer and de-multiplexer.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{	11588_717779,

title = {First observation of the quantized exciton-polariton field and effect of interactions on a single polariton},

author = {Álvaro Cuevas and Juan Camilo López Carreño and Blanca Silva and Milena De Giorgi and Daniel G. Suárez-Forero and Carlos Sánchez Muñoz and Antonio Fieramosca and Filippo Cardano and Lorenzo Marrucci and Vittorianna Tasco and Giorgio Biasiol and Elena Valle and Lorenzo Dominici and Dario Ballarini and Giuseppe Gigli and Paolo Mataloni and Fabrice P. Laussy and Fabio Sciarrino and Daniele Sanvitto},

doi = {10.1126/sciadv.aao6814},

year  = {2018},

date = {2018-01-01},

journal = {SCIENCE ADVANCES},

volume = {4},

number = {4},

abstract = {Polaritons are quasi-particles that originate from the coupling of light with matter and that demonstrate quan- tum phenomena at the many-particle mesoscopic level, such as Bose-Einstein condensation and superfluidity. A highly sought and long-time missing feature of polaritons is a genuine quantum manifestation of their dynamics at the single- particle level. Although they are conceptually perceived as entangled states and theoretical proposals abound for an explicit manifestation of their single-particle properties, so far their behavior has remained fully accounted for by clas- sical and mean-field theories. We report the first experimental demonstration of a genuinely quantum state of the microcavity polariton field, by swapping a photon for a polariton in a two-photon entangled state generated by para- metric downconversion. When bringing this single-polariton quantum state in contact with a polariton condensate, we observe a disentangling with the external photon. This manifestation of a polariton quantum state involving a single quantum unlocks new possibilities for quantum information processing with interacting bosons.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{	11588_689194,

title = {Measuring the complex orbital angular momentum spectrum and spatial mode decomposition of structured light beams},

author = {Alessio D'Errico and Raffaele D’Amelio and Bruno Piccirillo and Filippo Cardano and Lorenzo Marrucci},

doi = {10.1364/OPTICA.4.001350},

year  = {2017},

date = {2017-01-01},

journal = {OPTICA},

volume = {4},

number = {11},

abstract = {Light beams carrying orbital angular momentum are key resources in modern photonics. In many applications, the ability to measure the complex spectrum of structured light beams in terms of these fundamental modes is crucial. Here we propose and experimentally validate a simple method that achieves this goal by digital analysis of the interference pattern formed by the light beam and a reference field. Our approach allows one to also characterize the beam radial distribution, hence retrieving the entire information contained in the optical field. Setup simplicity and reduced number of measurements could make this approach practical and convenient for the characterization of structured light fields.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{	11588_663607,

title = {Interplay between diffraction and the Pancharatnam-Berry phase in inhomogeneously twisted anisotropic media},

author = {Chandroth P. Jisha and Alessandro Alberucci and Lorenzo Marrucci and Gaetano Assanto},

doi = {10.1103/PhysRevA.95.023823},

year  = {2017},

date = {2017-01-01},

journal = {PHYSICAL REVIEW A},

volume = {95},

number = {2},

abstract = {We discuss the propagation of an electromagnetic field in an inhomogeneously anisotropic material where the optic axis is rotated in the transverse plane but is invariant along the propagation direction. In such a configuration, the evolution of an electromagnetic wave packet is governed by the Pancharatnam-Berry phase (PBP), which is responsible for the appearance of an effective photonic potential. In a recent paper [ACS Photon. 3, 2249 (2016)] we demonstrated that the effective potential supports transverse confinement. Here we find the profile of the quasimodes and show that the photonic potential arises from the Kapitza effect of light. The theoretical results are confirmed by numerical simulations, accounting for the medium birefringence. Finally, we analyze in detail a configuration able to support nonleaky guided modes.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{	11588_677916,

title = {Monstar polarization singularities with elliptically-symmetric q-plates},

author = {Ben A. Cvarch and Behzad Khajavi and Joshua A. Jones and Bruno Piccirillo and Lorenzo Marrucci and Enrique J. Galvez},

doi = {10.1364/OE.25.014935},

year  = {2017},

date = {2017-01-01},

journal = {OPTICS EXPRESS},

volume = {25},

number = {13},

abstract = {Space-variant polarization patterns present in the transverse mode of optical beams highlight disclination patterns of polarization about a singularity, often a C-point. These patterns are important for understanding rotational dislocations and for characterizing complex polarization patterns. Liquid-crystal devices known as q-plates have been used to produce two of the three types of disclination patterns in optical beams: lemons and stars. Here we report the production of the third type of disclination, which is asymmetric, known as the monstar. We do so with elliptically-symmetric q-plates. We present theory and measurements, and find excellent agreement between the two.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{	11588_665356,

title = {Flat polarization-controlled cylindrical lens based on the Pancharatnam–Berry geometric phase},

author = {Bruno Piccirillo and Michela Florinda Picardi and Lorenzo Marrucci and Enrico Santamato},

doi = {10.1088/1361-6404/aa5e11},

year  = {2017},

date = {2017-01-01},

journal = {EUROPEAN JOURNAL OF PHYSICS},

volume = {38},

number = {3},

abstract = {The working principle of ordinary refractive lenses can be explained in terms of the space-variant optical phase retardations they introduce, which reshape the optical wavefront curvature and hence affect the subsequent light propagation. These phases, in turn, are due to the varying optical path length seen by light at different transverse positions relative to the lens centre. A similar lensing behavior can however be obtained when the optical phases are introduced by an entirely different mechanism. Here, we consider the “geometric phases” that arise from the polarization transforma- tions occurring in anisotropic optical media, named after Pancharatnam and Berry. The medium anisotropy axis is taken to be space-variant in the transverse plane and the resulting varying geomet- ric phases give rise to the wavefront reshaping and lensing effect, which however depends also on the input polarization. We describe the realization and characterization of a cylindrical geometric-phase lens that is converging for a given input circular polarization state and diverging for the orthogonal one, which provides one of the simplest possible examples of optical element based on geometric phases. The demonstrated lens is flat and only few microns thick (not including the supporting substrates); moreover, its working wavelength can be tuned and the lensing can be switched on and off by the action of an external control electric field. Other kinds of lenses or more general phase elements inducing different wavefront distortions can be obtained by a similar approach. Besides their potential for optoelectronic technology, these devices offer good opportunities for introducing college-level students to an advanced topic of modern physics, such as the Berry phase, with the help of interesting optical demonstrations.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{	11588_681085,

title = {Femtosecond laser surface structuring of silicon with Gaussian and optical vortex beams},

author = {Jijil nivas and He Shutong and Zhenming Song and Andrea Rubano and Antonio Vecchione and Domenico Paparo and Lorenzo Marrucci and Riccardo Bruzzese and Salvatore Amoruso},

url = {http://www.sciencedirect.com/science/article/pii/S0169433216322875?via%3Dihub},

doi = {10.1016/j.apsusc.2016.10.162},

year  = {2017},

date = {2017-01-01},

journal = {APPLIED SURFACE SCIENCE},

volume = {418},

pages = {565–571},

abstract = {We report an experimental analysis of femtosecond laser induced surface structuring of silicon by exploiting both Gaussian and Optical Vortex beams. In particular, we show how different surface patterns, consisting of quasi-periodic ripples and grooves, can be obtained by using different states of polarization offered by optical vortex beams. Both for Gaussian and optical vortex beams, an increase of the number of laser pulses, N, or beam energy, E-0, leads to a progressive predominance of the grooves coverage, with ripples confined in specific regions of the irradiated area at lower fluence. The average period of ripples and grooves shows a different dependence as a function of both E-0 and N, underlying important differences in mechanisms leading to the formation of ripples and grooves. In particular, our experimental characterization allows identifying a preliminary stage of grooves generation with rudimental surface structures, preferentially directed parallel to the laser polarization. This supports the idea that one possible mechanism of grooves formation lies in the progressive aggregation of clusters of nanopartides densely decorating the ripples. Our experimental findings provide important indications on the basic understanding of the processes involved in laser surface structuring with ultrashort pulses that can guide the design of the surface patterns. (C) 2016 Elsevier B.V. All rights reserved.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{11588_676887,

title = {Detection of Zak phases and topological invariants in a chiral quantum walk of twisted photons},

author = {Filippo Cardano and Alessio D'Errico and Alexandre Dauphin and Maria Maffei and Bruno Piccirillo and Corrado De Lisio and Giulio De Filippis and Vittorio Cataudella and Enrico Santamato and Lorenzo Marrucci and Maciej Lewenstein and Pietro Massignan},

doi = {10.1038/ncomms15516},

year  = {2017},

date = {2017-01-01},

urldate = {2017-01-01},

journal = {NATURE COMMUNICATIONS},

volume = {8},

abstract = {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.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}