Articles de revista
http://hdl.handle.net/2117/3271
Fri, 23 Jul 2021 17:01:23 GMT2021-07-23T17:01:23ZReversible self-replication of spatiotemporal Kerr cavity patterns
http://hdl.handle.net/2117/345089
Reversible self-replication of spatiotemporal Kerr cavity patterns
Benadouda Ivars, Salim; Kartashov, Yaroslav V.; Torner Sabata, Lluís; Conejero Casares, José Alberto; Milian Enrique, Carles
We uncover a novel and robust phenomenon that causes the gradual self-replication of spatiotemporal Kerr cavity patterns in cylindrical microresonators. These patterns are inherently synchronized multifrequency combs. Under proper conditions, the axially localized nature of the patterns leads to a fundamental drift instability that induces transitions among patterns with a different number of rows. Self-replications, thus, result in the stepwise addition or removal of individual combs along the cylinder’s axis. Transitions occur in a fully reversible and, consequently, deterministic way. The phenomenon puts forward a novel paradigm for Kerr frequency comb formation and reveals important insights into the physics of multidimensional nonlinear patterns.
Tue, 04 May 2021 13:10:32 GMThttp://hdl.handle.net/2117/3450892021-05-04T13:10:32ZBenadouda Ivars, SalimKartashov, Yaroslav V.Torner Sabata, LluísConejero Casares, José AlbertoMilian Enrique, CarlesWe uncover a novel and robust phenomenon that causes the gradual self-replication of spatiotemporal Kerr cavity patterns in cylindrical microresonators. These patterns are inherently synchronized multifrequency combs. Under proper conditions, the axially localized nature of the patterns leads to a fundamental drift instability that induces transitions among patterns with a different number of rows. Self-replications, thus, result in the stepwise addition or removal of individual combs along the cylinder’s axis. Transitions occur in a fully reversible and, consequently, deterministic way. The phenomenon puts forward a novel paradigm for Kerr frequency comb formation and reveals important insights into the physics of multidimensional nonlinear patterns.Quantum-inspired Fredkin gate based on spatial modes of light
http://hdl.handle.net/2117/345061
Quantum-inspired Fredkin gate based on spatial modes of light
Urrego González, Daniel Fernando; López Mago, Dorilian; Vicuña Hernández, Verónica; Pérez Torres, Juan
Insights gained from quantum physics can inspire novel classical technologies. These quantum-inspired technologies are protocols that aim at mimicking particular features of quantum algorithms. They are generally easier to implement and make use of intense beams. Here we demonstrate in a proof-of-concept experiment a quantum-inspired protocol based on the idea of quantum fingerprinting (Phys. Rev. Lett. 87, 167902, 2001).The carriers of information are optical beams with orbital angular momentum (OAM). These beams allow the implementation of a Fredkin gate or polarization-controlled SWAP operation that exchanges data encoded on beams with different OAM. We measure the degree of similarity between waveforms and strings of bits without unveiling the information content of the data
Tue, 04 May 2021 11:01:35 GMThttp://hdl.handle.net/2117/3450612021-05-04T11:01:35ZUrrego González, Daniel FernandoLópez Mago, DorilianVicuña Hernández, VerónicaPérez Torres, JuanInsights gained from quantum physics can inspire novel classical technologies. These quantum-inspired technologies are protocols that aim at mimicking particular features of quantum algorithms. They are generally easier to implement and make use of intense beams. Here we demonstrate in a proof-of-concept experiment a quantum-inspired protocol based on the idea of quantum fingerprinting (Phys. Rev. Lett. 87, 167902, 2001).The carriers of information are optical beams with orbital angular momentum (OAM). These beams allow the implementation of a Fredkin gate or polarization-controlled SWAP operation that exchanges data encoded on beams with different OAM. We measure the degree of similarity between waveforms and strings of bits without unveiling the information content of the dataOptical coherence tomography with a nonlinear interferometer in the high parametric gain regime
http://hdl.handle.net/2117/345054
Optical coherence tomography with a nonlinear interferometer in the high parametric gain regime
Jiménez Machado, Gerard; Frascella, Gaetano; Pérez Torres, Juan; Chekhova, Maria
We demonstrate optical coherence tomography based on an SU(1,1) nonlinear interferometer with high-gain parametric down-conversion. For imaging and sensing applications, this scheme promises to outperform previous experiments working at low parametric gain, since higher photon fluxes provide lower integration times for obtaining high-quality images. In this way one can avoid using single-photon detectors or CCD cameras with very high sensitivities, and standard spectrometers can be used instead. Other advantages are: higher sensitivity to small loss and amplification before detection, so that the detected light power considerably exceeds the probing one.
Tue, 04 May 2021 10:23:35 GMThttp://hdl.handle.net/2117/3450542021-05-04T10:23:35ZJiménez Machado, GerardFrascella, GaetanoPérez Torres, JuanChekhova, MariaWe demonstrate optical coherence tomography based on an SU(1,1) nonlinear interferometer with high-gain parametric down-conversion. For imaging and sensing applications, this scheme promises to outperform previous experiments working at low parametric gain, since higher photon fluxes provide lower integration times for obtaining high-quality images. In this way one can avoid using single-photon detectors or CCD cameras with very high sensitivities, and standard spectrometers can be used instead. Other advantages are: higher sensitivity to small loss and amplification before detection, so that the detected light power considerably exceeds the probing one.Frequency-correlation requirements on the biphoton wave function in an induced-coherence experiment between separate sources
http://hdl.handle.net/2117/344907
Frequency-correlation requirements on the biphoton wave function in an induced-coherence experiment between separate sources
Rojas Santana, Arturo; Jiménez Machado, Gerard; López Mago, Dorilian; Pérez Torres, Juan
There is renewed interest in using the coherence between beams generated in separate down-
converter sources for new applications in imaging, spectroscopy, microscopy and optical coherence
tomography (OCT). These schemes make use of continuous wave (CW) pumping in the low para-
metric gain regime, which produces frequency correlations, and frequency entanglement, between
signal-idler pairs generated in each single source. But can induced coherence still be observed if there
is no frequency correlation, so the biphoton wavefunction is factorable? We will show that this is the
case, and this might be an advantage for OCT applications. High axial resolution requires a large
bandwidth. For CW pumping this requires the use of short nonlinear crystals. This is detrimental
since short crystals generate small photon
uxes. We show that the use of ultrashort pump pulses
allows improving axial resolution even for long crystal that produce higher photon
uxes.
Fri, 30 Apr 2021 11:37:04 GMThttp://hdl.handle.net/2117/3449072021-04-30T11:37:04ZRojas Santana, ArturoJiménez Machado, GerardLópez Mago, DorilianPérez Torres, JuanThere is renewed interest in using the coherence between beams generated in separate down-
converter sources for new applications in imaging, spectroscopy, microscopy and optical coherence
tomography (OCT). These schemes make use of continuous wave (CW) pumping in the low para-
metric gain regime, which produces frequency correlations, and frequency entanglement, between
signal-idler pairs generated in each single source. But can induced coherence still be observed if there
is no frequency correlation, so the biphoton wavefunction is factorable? We will show that this is the
case, and this might be an advantage for OCT applications. High axial resolution requires a large
bandwidth. For CW pumping this requires the use of short nonlinear crystals. This is detrimental
since short crystals generate small photon
uxes. We show that the use of ultrashort pump pulses
allows improving axial resolution even for long crystal that produce higher photon
uxes.Nonlinearity-induced photonic topological insulator
http://hdl.handle.net/2117/339427
Nonlinearity-induced photonic topological insulator
Maczewsky, Lukas J.; Heinrich, Matthias; Kremer, Mark; Ivanov, Seergey K.; Ehrhardt, Max; Martínez, Franklin; Kartashov, Yaroslav V.; Konotop, Vladimir V.; Torner Sabata, Lluís; Bauer, Dieter; Szameit, Alexander
A hallmark feature of topological insulators is robust edge transport that is impervious to scattering at defects and lattice disorder. We demonstrate a topological system, using a photonic platform, in which the existence of the topological phase is brought about by optical nonlinearity. The lattice structure remains topologically trivial in the linear regime, but as the optical power is increased above a certain power threshold, the system is driven into the topologically nontrivial regime. This transition is marked by the transient emergence of a protected unidirectional transport channel along the edge of the structure. Our work studies topological properties of matter in the nonlinear regime, providing a possible route for the development of compact devices that harness topological features in an on-demand fashion.
Thu, 11 Feb 2021 11:54:55 GMThttp://hdl.handle.net/2117/3394272021-02-11T11:54:55ZMaczewsky, Lukas J.Heinrich, MatthiasKremer, MarkIvanov, Seergey K.Ehrhardt, MaxMartínez, FranklinKartashov, Yaroslav V.Konotop, Vladimir V.Torner Sabata, LluísBauer, DieterSzameit, AlexanderA hallmark feature of topological insulators is robust edge transport that is impervious to scattering at defects and lattice disorder. We demonstrate a topological system, using a photonic platform, in which the existence of the topological phase is brought about by optical nonlinearity. The lattice structure remains topologically trivial in the linear regime, but as the optical power is increased above a certain power threshold, the system is driven into the topologically nontrivial regime. This transition is marked by the transient emergence of a protected unidirectional transport channel along the edge of the structure. Our work studies topological properties of matter in the nonlinear regime, providing a possible route for the development of compact devices that harness topological features in an on-demand fashion.Spiraling vortices in exciton-polariton condensates
http://hdl.handle.net/2117/338173
Spiraling vortices in exciton-polariton condensates
Ma, Xuekai; Kartashov, Yaroslav V.; Gao, Tingge; Torner Sabata, Lluís; Schumacher, Stefan
We introduce the phenomenon of spiraling vortices in driven-dissipative (nonequilibrium) exciton-polariton condensates excited by a nonresonant pump beam. At suitable low pump intensities, these vortices are shown to spiral along circular trajectories whose diameter is inversely proportional to the effective mass of the polaritons, while the rotation period is mass independent. Both the diameter and rotation period are inversely proportional to the pump intensity. Stable spiraling patterns in the form of complexes of multiple mutually interacting vortices are also found. At elevated pump intensities, which create a stronger homogeneous background, we observe more complex vortex trajectories resembling Spirograph patterns.
Tue, 09 Feb 2021 14:46:56 GMThttp://hdl.handle.net/2117/3381732021-02-09T14:46:56ZMa, XuekaiKartashov, Yaroslav V.Gao, TinggeTorner Sabata, LluísSchumacher, StefanWe introduce the phenomenon of spiraling vortices in driven-dissipative (nonequilibrium) exciton-polariton condensates excited by a nonresonant pump beam. At suitable low pump intensities, these vortices are shown to spiral along circular trajectories whose diameter is inversely proportional to the effective mass of the polaritons, while the rotation period is mass independent. Both the diameter and rotation period are inversely proportional to the pump intensity. Stable spiraling patterns in the form of complexes of multiple mutually interacting vortices are also found. At elevated pump intensities, which create a stronger homogeneous background, we observe more complex vortex trajectories resembling Spirograph patterns.Ultrashort pulse characterisation with SHG collinear-FROG
http://hdl.handle.net/2117/336125
Ultrashort pulse characterisation with SHG collinear-FROG
Amat Roldán, Iván; Cormack, Iain G.; Loza Álvarez, Pablo; Gualda Manzano, Emilio José; Artigas García, David
We outline criteria for fast and accurate acquisition of collinear FROG (CFROG) trace and how it can be transformed into the more traditional noncollinear FROG trace. The CFROG has an intrinsically simple geometry that provides greater versatility as well as the ability for built-in delay calibration and enhanced error-checking. The procedure, based on data processing, allows conventional SHG-FROG retrieval algorithms to be used. This technique is tested numerically and experimentally giving excellent results. This work represents an attractive alternative to the traditional, more complex non-collinear FROG technique while, at the same time, extending its use to experiments where collinear geometry is imposed.
Thu, 28 Jan 2021 06:52:30 GMThttp://hdl.handle.net/2117/3361252021-01-28T06:52:30ZAmat Roldán, IvánCormack, Iain G.Loza Álvarez, PabloGualda Manzano, Emilio JoséArtigas García, DavidWe outline criteria for fast and accurate acquisition of collinear FROG (CFROG) trace and how it can be transformed into the more traditional noncollinear FROG trace. The CFROG has an intrinsically simple geometry that provides greater versatility as well as the ability for built-in delay calibration and enhanced error-checking. The procedure, based on data processing, allows conventional SHG-FROG retrieval algorithms to be used. This technique is tested numerically and experimentally giving excellent results. This work represents an attractive alternative to the traditional, more complex non-collinear FROG technique while, at the same time, extending its use to experiments where collinear geometry is imposed.Angular control of anisotropy-induced bound states in the continuum
http://hdl.handle.net/2117/180892
Angular control of anisotropy-induced bound states in the continuum
Mukherjee, Samyobrata; Gomis Bresco, Jordi; Pujol Closa, Maria del Pilar; Artigas García, David; Torner Sabata, Lluís
Radiation of leaky modes existing in anisotropic waveguides can be cancelled by destructive
interference at special propagation directions relative to the optical axis orientation, resulting in
fully bound states surrounded by radiative modes. Here we study the variation of the loci of such
special directions in terms of the waveguide constitutive parameters. We show that the angular
loci of the bound states is sensitive to several design parameters, allowing bound states to exist for
a broad range of angular directions and wavelengths and suggesting applications in filtering and
sensing.
Mon, 23 Mar 2020 11:51:02 GMThttp://hdl.handle.net/2117/1808922020-03-23T11:51:02ZMukherjee, SamyobrataGomis Bresco, JordiPujol Closa, Maria del PilarArtigas García, DavidTorner Sabata, LluísRadiation of leaky modes existing in anisotropic waveguides can be cancelled by destructive
interference at special propagation directions relative to the optical axis orientation, resulting in
fully bound states surrounded by radiative modes. Here we study the variation of the loci of such
special directions in terms of the waveguide constitutive parameters. We show that the angular
loci of the bound states is sensitive to several design parameters, allowing bound states to exist for
a broad range of angular directions and wavelengths and suggesting applications in filtering and
sensing.Transition from Dirac points to exceptional points in anisotropic waveguides
http://hdl.handle.net/2117/180876
Transition from Dirac points to exceptional points in anisotropic waveguides
Gomis Bresco, Jordi; Artigas García, David; Torner Sabata, Lluís
We uncover the existence of Dirac and exceptional points in waveguides made of anisotropic materials, and study the transition between them. Dirac points in the dispersion diagram appear at propagation directions where the matrix describing the eigenvalue problem for bound states splits into two blocks, sorting the eigenmodes either by polarization or by inner mode symmetry. Introducing a non-Hermitian channel via a suitable leakage mechanism causes the Dirac points to transform into exceptional points connected by a Fermi arc. The exceptional points arise as improper hybrid leaky states and, importantly, are found to occur always out of the anisotropy symmetry planes.
Mon, 23 Mar 2020 10:58:07 GMThttp://hdl.handle.net/2117/1808762020-03-23T10:58:07ZGomis Bresco, JordiArtigas García, DavidTorner Sabata, LluísWe uncover the existence of Dirac and exceptional points in waveguides made of anisotropic materials, and study the transition between them. Dirac points in the dispersion diagram appear at propagation directions where the matrix describing the eigenvalue problem for bound states splits into two blocks, sorting the eigenmodes either by polarization or by inner mode symmetry. Introducing a non-Hermitian channel via a suitable leakage mechanism causes the Dirac points to transform into exceptional points connected by a Fermi arc. The exceptional points arise as improper hybrid leaky states and, importantly, are found to occur always out of the anisotropy symmetry planes.Random number generation by coherent detection of quantum phase noise
http://hdl.handle.net/2117/179831
Random number generation by coherent detection of quantum phase noise
Álvarez, Juan Rafael; Sarmiento Hernández, Samael; Lázaro Villa, José Antonio; Gené Bernaus, Joan M.; Pérez Torres, Juan
In 2010 Qi et al. [Opt. Lett. 35(3), 312 (2010)] demonstrated a random number generator based on the drift of the phase of a laser due to spontaneous emission, The out-of-the-lab implementation of this scheme presents two main drawbacks: it requires a long and highly unbalanced interferometer to generate a random phase with uniform probability distribution, or alternatively, a shorter and slightly unbalanced interferometer that notwithstanding requires active stabilization and does not generate a uniform probability distribution without randomness extraction. Here we demonstrate that making use of the random nature of the phase difference between two independent laser sources and two coherent detectors we can overcome these limitations. The two main advantages of the system demonstrated are: i) it generates a probability distribution of quantum origin which is intrinsically uniform and thus in principle needs no randomness extraction for obtaining a uniform distribution, and ii) the phase is measured with telecom equipment routinely used for high capacity coherent optical communications. The speed of random bit generation is determined by the photodetector bandwidth and the linewidth of the lasers. As a by-product of our method, we have obtained images of how phase noise develops with time in a laser. This provides a highly visual alternative way of measuring the coherence time of a laser.
Thu, 12 Mar 2020 16:06:03 GMThttp://hdl.handle.net/2117/1798312020-03-12T16:06:03ZÁlvarez, Juan RafaelSarmiento Hernández, SamaelLázaro Villa, José AntonioGené Bernaus, Joan M.Pérez Torres, JuanIn 2010 Qi et al. [Opt. Lett. 35(3), 312 (2010)] demonstrated a random number generator based on the drift of the phase of a laser due to spontaneous emission, The out-of-the-lab implementation of this scheme presents two main drawbacks: it requires a long and highly unbalanced interferometer to generate a random phase with uniform probability distribution, or alternatively, a shorter and slightly unbalanced interferometer that notwithstanding requires active stabilization and does not generate a uniform probability distribution without randomness extraction. Here we demonstrate that making use of the random nature of the phase difference between two independent laser sources and two coherent detectors we can overcome these limitations. The two main advantages of the system demonstrated are: i) it generates a probability distribution of quantum origin which is intrinsically uniform and thus in principle needs no randomness extraction for obtaining a uniform distribution, and ii) the phase is measured with telecom equipment routinely used for high capacity coherent optical communications. The speed of random bit generation is determined by the photodetector bandwidth and the linewidth of the lasers. As a by-product of our method, we have obtained images of how phase noise develops with time in a laser. This provides a highly visual alternative way of measuring the coherence time of a laser.