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GotThatData
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-  {
-    "title": "Super-luminal Synthetic Motion with a Space-Time Optical Metasurface",
-    "authors": [
-      "A. C. Harwood",
-      "S. Vezzoli",
-      "T. V. Raziman",
-      "C. Hooper",
-      "R. Tirole",
-      "F. Wu",
-      "S. A. Maier",
-      "J. B. Pendry",
-      "S. A. R. Horsley",
-      "R. Sapienza"
-    ],
-    "abstract": "The interaction of light with superluminally moving matter entails unconventional phenomena, from Fresnel drag to Hawking radiation and to light amplification. While relativity makes these effects inaccessible using objects in motion, synthetic motion - enabled via space-time modulated internal degrees of freedom - is free from these constraints. Here we observe synthetic velocity of a reflectivity modulation travelling on an Indium-Tin-Oxide (ITO) interface, generated by ultrafast laser illumination at multiple positions and times. The interaction of the moving reflectivity modulation with a probe light beam acts as a non-separable spatio-temporal transformation that diffracts the light, changing its frequency and momentum content. The recorded frequency-momentum diffraction pattern is defined by the velocity of the diffracted probe wave relative to the modulation. Our experiments open a path towards mimicking relativistic mechanics and developing programmable spatio-temporal transformations of light.",
-    "arxiv_id": "2407.10809v2",
-    "categories": [
-      "physics.optics",
-      "cond-mat.mtrl-sci"
-    ],
-    "primary_category": "physics.optics",
-    "published_date": "2024-07-15T15:24:55Z",
-    "updated_date": "2024-11-04T10:16:21Z",
-    "pdf_url": "https://arxiv.org/pdf/2407.10809v2",
-    "local_pdf_path": "data\\arxiv\\pdfs\\materials\\2407.10809v2.pdf",
-    "comment": "",
-    "journal_ref": "",
-    "doi": ""
-  },
-  {
-    "title": "Superluminal Propagation of Composite Collective Modes in   Superconductor-Ferromagnet Heterostructures",
-    "authors": [
-      "Pascal Derendorf",
-      "Anatoly F. Volkov",
-      "Ilya M. Eremin"
-    ],
-    "abstract": "Superconductor/ferromagnet/superconductor Josephson junctions are paradigmatic systems for studying the delicate interplay of superconductivity and magnetism via proximity effects as well as their composite excitations. Here, we analyse the collective modes (CM) in such a heterostructure by taking into account the interplay between the de-magnetisation field $H_{dem}$ and the field caused by the anisotropy of the ferromagnet $H_{an}$, which was previously neglected. It turns out that the spectrum of composite collective modes, $\\omega(k)$, has a qualitatively different form in the case of $H_{dem}<H_{an}$ and of $H_{dem}>H_{an}$. In the first case, the dependence $\\omega(k)$ has the same form as in previous studies, whereas in the second case, the spectrum looks completely different. In particular, for moderate or weak anisotropy in ferromagnet the group velocity of collective modes demonstrates inflection point where the group velocity become infinite and is superluminal. Furthermore, this point separates purely real and complex-conjugate solutions for the collective modes and is also {\\it exception point}. We show that the difference of the CMs spectra can be revealed by Fiske experiment, i.\\,e.\\,by measuring the $I-V$ characteristics in the presence of magnetic field and voltage.",
-    "arxiv_id": "2407.05457v2",
-    "categories": [
-      "cond-mat.supr-con",
-      "cond-mat.stat-mech",
-      "cond-mat.str-el",
-      "quant-ph"
-    ],
-    "primary_category": "cond-mat.supr-con",
-    "published_date": "2024-07-07T18:01:17Z",
-    "updated_date": "2024-10-03T12:09:21Z",
-    "pdf_url": "https://arxiv.org/pdf/2407.05457v2",
-    "local_pdf_path": "data\\arxiv\\pdfs\\materials\\2407.05457v2.pdf",
-    "comment": "",
-    "journal_ref": "",
-    "doi": ""
-  },
-  {
-    "title": "Anomalous dispersion, superluminality and instabilities in two-flavour   theories with local non-Hermitian mass mixing",
-    "authors": [
-      "Maxim N. Chernodub",
-      "Peter Millington"
-    ],
-    "abstract": "Pseudo-Hermitian field theories possess a global continuous ``similarity'' symmetry, interconnecting the theories with the same physical particle content and an identical mass spectrum. In their regimes with real spectra, within this family of similarity transformations, there is a map from the non-Hermitian theory to its Hermitian similarity partner. We promote the similarity transformation to a local symmetry, which requires the introduction of a new vector similarity field as a connection in the similarity space of non-Hermitian theories. In the case of non-Hermitian two-flavour scalar or fermion mixing, and by virtue of a novel IR/UV mixing effect, the effect of inhomogeneous non-Hermiticity then reveals itself via anomalous dispersion, instabilities and superluminal group velocities at very high momenta, thus setting an upper bound on the particle momentum propagating through inhomogeneous backgrounds characterised by Lagrangians with non-Hermitian mass matrices. Such a non-Hermitian extension of the Standard Model of particle physics, encoded in a weak inhomogeneity of the non-Hermitian part of the fermion mass matrix, may nevertheless provide us with a low-energy particle spectrum consistent with experimentally observed properties.",
-    "arxiv_id": "2401.06097v1",
-    "categories": [
-      "hep-th",
-      "cond-mat.other",
-      "hep-ph"
-    ],
-    "primary_category": "hep-th",
-    "published_date": "2024-01-11T18:21:42Z",
-    "updated_date": "2024-01-11T18:21:42Z",
-    "pdf_url": "https://arxiv.org/pdf/2401.06097v1",
-    "local_pdf_path": "data\\arxiv\\pdfs\\materials\\2401.06097v1.pdf",
-    "comment": "",
-    "journal_ref": "",
-    "doi": ""
-  },
-  {
-    "title": "Nonminimal planar electrodynamics modified by higher-derivative terms",
-    "authors": [
-      "Let\u00edcia Lisboa-Santos",
-      "Jo\u00e3o A. A. S. Reis",
-      "Marco Schreck",
-      "Manoel M. Ferreira"
-    ],
-    "abstract": "We consider a (2+1)-dimensional modified electrodynamics endowed with terms that are either Lorentz-invariant or Lorentz-violating and involve an ever increasing number of derivatives. Our construction relies on U(1) gauge invariance and the Abelian Chern-Simons term poses the starting point. The structure of the nonminimal Standard-Model Extension (SME) in (3+1) spacetime dimensions serves as an inspiration for our pursuit. For elaborate studies and applications we particularly focus on the second term of the operator series in the general framework, which is the first contribution with additional derivatives. The latter forms the essential ingredient for several models of modified planar electrodynamics to be examined. The propagators of the models constitute the foundation for us deriving the physical propagating modes as well as for drawing conclusions on unitarity in the quantum regime. We are also interested in identifying parameter regions of sub- and superluminal mode propagation and determine classical solutions of the field equations for the planar models introduced. Moreover, a duality between an extended Chern-Simons theory and a subset of the fermion sector coefficients in the nonminimal SME is pointed out, as well. Finally, the integer quantum Hall effect is chosen as a testbed to demonstrate the applicability of our findings to real physical systems. Predictions on momentum- and direction-dependent corrections of the Hall resistivity are made at the level of effective field theory, which could be tested in experiments. Thus, the (2+1)-dimensional models proposed are potentially applicable to model electromagnetic phenomena in certain planar condensed-matter systems.",
-    "arxiv_id": "2309.16839v1",
-    "categories": [
-      "hep-th",
-      "cond-mat.other"
-    ],
-    "primary_category": "hep-th",
-    "published_date": "2023-09-28T20:40:47Z",
-    "updated_date": "2023-09-28T20:40:47Z",
-    "pdf_url": "https://arxiv.org/pdf/2309.16839v1",
-    "local_pdf_path": "data\\arxiv\\pdfs\\materials\\2309.16839v1.pdf",
-    "comment": "",
-    "journal_ref": "",
-    "doi": ""
-  },
-  {
-    "title": "Non-Hermitian Hartman effect",
-    "authors": [
-      "Stefano Longhi"
-    ],
-    "abstract": "The Hartman effect refers to the rather paradoxical result that the time spent by a quantum mechanical particle or a photon to tunnel through an opaque potential barrier becomes independent of barrier width for long barriers. Such an effect, which has been observed in different physical settings, raised a lively debate and some controversies, owing to the correct definition and interpretation of tunneling times and the apparent superluminal transmission. A rather open question is whether (and under which conditions) the Hartman effect persists for inelastic scattering, i.e. when the potential becomes non-Hermitian and the scattering matrix is not unitary. Here we consider tunneling through a heterojunction barrier in the tight-binding picture, where the barrier consists of a generally non-Hermitian finite-sized lattice attached to two semi-infinite nearest-neighbor Hermitian lattice leads. We derive a simple and general condition for the persistence of the Hartman effect in non-Hermitian barriers, showing that it can be found rather generally when non-Hermiticity arises from non-reciprocal couplings, i.e. when the barrier displays the non-Hermitian skin effect, without any special symmetry in the system.",
-    "arxiv_id": "2207.08715v1",
-    "categories": [
-      "quant-ph",
-      "cond-mat.str-el",
-      "physics.optics"
-    ],
-    "primary_category": "quant-ph",
-    "published_date": "2022-07-18T16:00:27Z",
-    "updated_date": "2022-07-18T16:00:27Z",
-    "pdf_url": "https://arxiv.org/pdf/2207.08715v1",
-    "local_pdf_path": "data\\arxiv\\pdfs\\materials\\2207.08715v1.pdf",
-    "comment": "",
-    "journal_ref": "",
-    "doi": ""
-  },
-  {
-    "title": "Chronology Protection Implementation in Analogue Gravity",
-    "authors": [
-      "Carlos Barcel\u00f3",
-      "Jokin Eguia S\u00e1nchez",
-      "Gerardo Garc\u00eda-Moreno",
-      "Gil Jannes"
-    ],
-    "abstract": "Analogue gravity systems offer many insights into gravitational phenomena, both at the classical and at the semiclassical level. The existence of an underlying Minkowskian structure (or Galilean in the non-relativistic limit) in the laboratory has been argued to directly forbid the simulation of geometries with Closed Timelike Curves (CTCs) within analogue systems. We will show that this is not strictly the case. In principle, it is possible to simulate spacetimes with CTCs whenever this does not entail the presence of a chronological horizon separating regions with CTCs from regions that do not have CTCs. We find an Analogue-gravity Chronology protection mechanism very similar in spirit to Hawking's Chronology Protection hypothesis. We identify the universal behaviour of analogue systems near the formation of such horizons and discuss the further implications that this analysis has from an emergent gravity perspective. Furthermore, we build explicit geometries containing CTCs, for instance spacetimes constructed from two warp-drive configurations, that might be useful for future analysis, both from a theoretical and an experimental point of view.",
-    "arxiv_id": "2201.11072v2",
-    "categories": [
-      "gr-qc",
-      "cond-mat.other",
-      "hep-th"
-    ],
-    "primary_category": "gr-qc",
-    "published_date": "2022-01-26T17:32:32Z",
-    "updated_date": "2022-04-07T08:13:08Z",
-    "pdf_url": "https://arxiv.org/pdf/2201.11072v2",
-    "local_pdf_path": "data\\arxiv\\pdfs\\materials\\2201.11072v2.pdf",
-    "comment": "",
-    "journal_ref": "",
-    "doi": ""
-  },
-  {
-    "title": "Relativistic origin of Hertz-form and extended Hertz-form equations for   Maxwell theory of electromagnetism",
-    "authors": [
-      "Fei Wang",
-      "Jin Min Yang"
-    ],
-    "abstract": "We show explicitly that the Hertz-form Maxwell's equations and their extensions can be obtained from the non-relativistic expansion of Lorentz transformation of Maxwell's equations. The explicit expression for the parameter $\\alpha$ in the extended Hertz-form equations can be derived from such a non-relativistic expansion. The extended Hertz-form equations, which do not preserve Galilean invariance, origin from Lorentz transformation of Maxwell's equations and differ from the Galilean-transformed Maxwell equations (the original Hertz equations) by the relative sign differences between the two $\\alpha$ terms etc. Especially, the $\\alpha$ parameter is of relativistic origin. The superluminal behavior illustrated by the D'Alembert equation from the extended Hertz-form equations should be removed by including all subleading contributions in the $v/c$ expansion, although such a superluminal behavior will not occur in the vacuum because $\\alpha=0$. We should note that in the Hertz form and extended Hertz form equations, the electromagnetic fields should take the forms $ \\vec{\\mathcal{E}}(x)=\\vec{E}(\\Lambda^{-1}x)$ and $ \\vec{\\mathcal{B}}(x)=\\vec{B}(\\Lambda^{-1}x)$. Such a choice of description for the fields is different from the ordinary one with $\\vec{E}(x)$ and $\\vec{B}(x)$, which are well known to satisfy the ordinary Maxwell's equations. The descriptions of electromagnetic phenomena using the function set $\\{\\vec{\\mathcal{E}}(x),\\vec{\\mathcal{B}}(x)\\}$ and the function set $(\\vec{E}(x),\\vec{B}(x))$ are equivalent, with the $\\{\\vec{\\mathcal{E}}(x),\\vec{\\mathcal{B}}(x)\\}$ description satisfying the extended Hertz-form Maxwell's equations in the low speed approximation. The solution of (extended) Hertz-form Maxwell's equations describe the traveling wave form electromagnetic field.",
-    "arxiv_id": "2201.10856v4",
-    "categories": [
-      "physics.class-ph",
-      "cond-mat.mes-hall",
-      "cond-mat.mtrl-sci"
-    ],
-    "primary_category": "physics.class-ph",
-    "published_date": "2022-01-26T10:36:13Z",
-    "updated_date": "2022-03-24T19:22:02Z",
-    "pdf_url": "https://arxiv.org/pdf/2201.10856v4",
-    "local_pdf_path": "data\\arxiv\\pdfs\\materials\\2201.10856v4.pdf",
-    "comment": "",
-    "journal_ref": "",
-    "doi": ""
-  },
-  {
-    "title": "The Transfer Matrix Method and The Theory of Finite Periodic Systems.   From Heterostructures to Superlattices",
-    "authors": [
-      "Pedro Pereyra"
-    ],
-    "abstract": "Long-period systems and superlattices, with additional periodicity, have new effects on the energy spectrum and wave functions. Most approaches adjust theories for infinite systems, which is acceptable for large but not small number of unit cells $n$. In the past 30 years, a theory based entirely on transfer matrices was developed, where the finiteness of $n$ is an essential condition. The theory of finite periodic systems (TFPS) is also valid for any number of propagating modes, and arbitrary potential profiles (or refractive indices). We review this theory, the transfer matrix definition, symmetry properties, group representations, and relations with the scattering amplitudes. We summarize the derivation of multichannel matrix polynomials (which reduce to Chebyshev polynomials in the one-propagating mode limit), the analytical formulas for resonant states, energy eigenvalues, eigenfunctions, parity symmetries, and discrete dispersion relations, for superlattices with different confinement characteristics. After showing the inconsistencies and limitations of hybrid approaches that combine the transfer-matrix method with Floquet's theorem, we review some applications of the TFPS to multichannel negative resistance, ballistic transistors, channel coupling, spintronics, superluminal, and optical antimatter effects. We review two high-resolution experiments using superlattices: tunneling time in photonic band-gap and optical response of blue-emitting diodes, and show extremely accurate theoretical predictions.",
-    "arxiv_id": "2109.11640v4",
-    "categories": [
-      "cond-mat.mtrl-sci",
-      "quant-ph"
-    ],
-    "primary_category": "cond-mat.mtrl-sci",
-    "published_date": "2021-09-23T20:45:29Z",
-    "updated_date": "2021-11-20T18:16:49Z",
-    "pdf_url": "https://arxiv.org/pdf/2109.11640v4",
-    "local_pdf_path": "data\\arxiv\\pdfs\\materials\\2109.11640v4.pdf",
-    "comment": "",
-    "journal_ref": "",
-    "doi": ""
-  },
-  {
-    "title": "Photonic transmittance in metallic and metamaterial Superlattices",
-    "authors": [
-      "Pedro Pereyra"
-    ],
-    "abstract": "We present here the transmission of electromagnetic waves through layered structures of metallic and left-handed media. Based on the theory of finite periodic systems, we show that besides the strong influence of the incidence angle, the low transmission characteristic of a single conductor slab, for frequencies $\\omega$ below the plasma frequency $\\omega_p$, becomes in this domain highly oscillating. Similarly, the well-established transmission coefficient of a single left-handed slab becomes highly resonant with superluminal effects in superlattices with more than one unit cell. We determine the space-time evolution of a wave packet through the $\\lambda/4$ photonic superlattice whose transmission coefficient is a sequence of isolated and equidistant peaks with negative phase times. We show that the space-time evolution of a Gaussian wave packet, with centroid at any of these peaks, agrees with the theoretical predictions, and no violation of the causality principle occurs.   We show that besides the strong influence of the incidence angle, the coherent coupling of the bulk plasmon modes and the interface surface plasmon polaritons lead to oscillating transmission coefficients, and depending on the parity of the number of unit cells $n$ of the superlattice, the transmission vanishes or amplifies as the conductor width increases. We determine the space-time evolution of a wave packet through the $\\lambda/4$ photonic superlattice whose bandwidth becomes negligible, and the transmission coefficient becomes a sequence of isolated and equidistant peaks with negative phase times. We show that the space-time evolution of a Gaussian wave packet, with the centroid at any of these peaks, agrees with the theoretical predictions, and no violation of the causality principle occurs.",
-    "arxiv_id": "2012.10546v1",
-    "categories": [
-      "physics.optics",
-      "cond-mat.mtrl-sci"
-    ],
-    "primary_category": "physics.optics",
-    "published_date": "2020-12-18T22:49:26Z",
-    "updated_date": "2020-12-18T22:49:26Z",
-    "pdf_url": "https://arxiv.org/pdf/2012.10546v1",
-    "local_pdf_path": "data\\arxiv\\pdfs\\materials\\2012.10546v1.pdf",
-    "comment": "",
-    "journal_ref": "",
-    "doi": ""
-  },
-  {
-    "title": "Superluminal moving defects in the Ising spin chain",
-    "authors": [
-      "Alvise Bastianello",
-      "Andrea De Luca"
-    ],
-    "abstract": "Quantum excitations in lattice systems always propagate at a finite maximum velocity. We probe this mechanism by considering a defect travelling at a constant velocity in the quantum Ising spin chain in transverse field. Independently of the microscopic details of the defect, we characterize the expectation value of local observables at large times and large distances from the impurity, where a Local Quasi Stationary State (LQSS) emerges. The LQSS is strongly affected by the defect velocity: for superluminal defects, it exhibits a growing region where translational invariance is spontaneously restored. We also analyze the behavior of the friction force exerted by the many-body system on the moving defect, which reflects the energy required by the LQSS formation. Exact results are provided in the two limits of extremely narrow and very smooth impurity. Possible extensions to more general free-fermion models and interacting systems are discussed",
-    "arxiv_id": "1805.00405v2",
-    "categories": [
-      "cond-mat.stat-mech",
-      "cond-mat.str-el",
-      "quant-ph"
-    ],
-    "primary_category": "cond-mat.stat-mech",
-    "published_date": "2018-05-01T15:46:04Z",
-    "updated_date": "2018-08-21T08:14:45Z",
-    "pdf_url": "https://arxiv.org/pdf/1805.00405v2",
-    "local_pdf_path": "data\\arxiv\\pdfs\\materials\\1805.00405v2.pdf",
-    "comment": "",
-    "journal_ref": "",
-    "doi": ""
-  },
-  {
-    "title": "Superluminal X-waves in a polariton quantum fluid",
-    "authors": [
-      "A. Gianfrate",
-      "L. Dominici",
-      "O. Voronych",
-      "M. Matuszewski",
-      "M. Stobi\u0144ska",
-      "D. Ballarini",
-      "M. De Giorgi",
-      "G. Gigli",
-      "D. Sanvitto"
-    ],
-    "abstract": "In this work we experimentally demonstrate for the first time spontaneous generation of two-dimensional exciton-polariton X-waves. X-waves belong to the family of localized packets, which are capable of sustaining their shape with no spreading even in the linear regime. This allows to keep the packet shape and size for very low densities and very long times compared, for instance, to soliton waves, which always necessitate a nonlinearity to compensate the diffusion. Here we exploit the polariton nonlinearity and unique structured dispersion, comprising both positive- and negative-mass curvatures, to trigger an asymmetric four wave mixing in the momentum space. This ultimately enables self-formation of a spatial X-wave front. By means of ultrafast imaging experiments we observe the early reshaping of the initial Gaussian packet into the X-pulse and its propagation even for vanishing small densities. This allows us to outline the crucial effects and parameters driving the phenomena and to tune the degree of peak superluminal propagation, which we found to be in a good agreement with numerical simulations.",
-    "arxiv_id": "1703.02313v2",
-    "categories": [
-      "cond-mat.other",
-      "cond-mat.quant-gas",
-      "nlin.PS",
-      "physics.flu-dyn"
-    ],
-    "primary_category": "cond-mat.other",
-    "published_date": "2017-03-07T10:29:20Z",
-    "updated_date": "2018-02-07T16:03:25Z",
-    "pdf_url": "https://arxiv.org/pdf/1703.02313v2",
-    "local_pdf_path": "data\\arxiv\\pdfs\\materials\\1703.02313v2.pdf",
-    "comment": "",
-    "journal_ref": "",
-    "doi": ""
-  },
-  {
-    "title": "Pulse generation with ultra-superluminal pulse propagation in   semiconductor heterostructures by superradiant phase transition enhanced by   transient coherent population gratings",
-    "authors": [
-      "Peter P. Vasil'ev",
-      "Richard V. Penty",
-      "Ian H. White"
-    ],
-    "abstract": "This paper reports the observation of ultra-superluminal pulse propagation in GaAs/AlGaAs multiple contact heterostuctures in a superradiant emission regime, and shows definitively that it is a different class of emission from conventional spontaneous or stimulated emission. It is shown that coherent population gratings induced in the semiconductor medium under strong electrical pumping have great impact in causing a decrease of the group refractive index in the range of 5-40%. This decrease is much greater than that which would be observed due to conventional carrier depletion or chirp mechanisms. The decrease in refractive index in turn causes faster-than-c propagation of femtosecond pulses. The measurement also shows unequivocally the exist of coherent amplification of electromagnetic pulses in semiconductors at room temperature, the coherence being strongly enhanced by interactions of the light with coherent transient gratings locked to carrier gratings. This pulse generation technique can be anticipated to have great potential in applications where highly coherent femtosecond optical pulses must be generated on demand",
-    "arxiv_id": "1508.05800v1",
-    "categories": [
-      "cond-mat.str-el",
-      "physics.optics",
-      "82C26"
-    ],
-    "primary_category": "cond-mat.str-el",
-    "published_date": "2015-08-24T13:35:30Z",
-    "updated_date": "2015-08-24T13:35:30Z",
-    "pdf_url": "https://arxiv.org/pdf/1508.05800v1",
-    "local_pdf_path": "data\\arxiv\\pdfs\\materials\\1508.05800v1.pdf",
-    "comment": "",
-    "journal_ref": "",
-    "doi": ""
-  },
-  {
-    "title": "Chiral fermions as classical massless spinning particles",
-    "authors": [
-      "C. Duval",
-      "P. A. Horvathy"
-    ],
-    "abstract": "Semiclassical chiral fermion models with Berry term are studied in a symplectic framework. In the free case, the system can be obtained from Souriau's model for a relativistic massless spinning particle by \"enslaving\" the spin. The Berry term is identified with the classical spin two-form of the latter model. The Souriau model carries a natural Poincar\\'e symmetry that we highlight, but spin enslavement breaks the boost symmetry. However the relation between the models allows us to derive a Poincare symmetry of unconventional form for chiral fermions. Then we couple our system to an external electromagnetic field. For gyromagnetic ratio $g=0$ we get curious superluminal Hall-type motions; for $g=2$ and in a pure constant magnetic field in particular, we find instead spiraling motions.",
-    "arxiv_id": "1406.0718v4",
-    "categories": [
-      "hep-th",
-      "cond-mat.str-el",
-      "hep-ph",
-      "math-ph",
-      "math.MP"
-    ],
-    "primary_category": "hep-th",
-    "published_date": "2014-06-03T14:08:57Z",
-    "updated_date": "2015-01-23T17:07:24Z",
-    "pdf_url": "https://arxiv.org/pdf/1406.0718v4",
-    "local_pdf_path": "data\\arxiv\\pdfs\\materials\\1406.0718v4.pdf",
-    "comment": "",
-    "journal_ref": "",
-    "doi": ""
-  },
-  {
-    "title": "Breaking the light speed barrier",
-    "authors": [
-      "O. I. Chashchina",
-      "Z. K. Silagadze"
-    ],
-    "abstract": "As it is well known, classical special relativity allows the existence of three different kinds of particles: bradyons, luxons and tachyons. Bradyons have non-zero mass and hence always travel slower than light. Luxons are particles with zero mass, like the photon, and they always travel with invariant velocity. Tachyons are hypothetical superluminal particles that always move faster than light. The existence of bradyons and luxons is firmly established, while the tachyons were never reliably observed. In quantum field theory, the appearance of tachyonic degrees of freedom indicates vacuum instability rather than a real existence of the faster-than-light particles. However, recent controversial claims of the OPERA experiment about superluminal neutrinos triggered a renewed interest in superluminal particles. Driven by a striking analogy of the old Frenkel-Kontorova model of a dislocation dynamics to the theory of relativity, we conjecture in this note a remarkable possibility of existence of the fourth type of particles, elvisebrions, which can be superluminal. The characteristic feature of elvisebrions, distinguishing them from tachyons, is that they are outside the realm of special relativity and their energy remains finite (or may even turn to zero) when the elvisebrion velocity approaches the light velocity.",
-    "arxiv_id": "1112.4714v3",
-    "categories": [
-      "hep-ph",
-      "cond-mat.other",
-      "hep-th",
-      "physics.class-ph"
-    ],
-    "primary_category": "hep-ph",
-    "published_date": "2011-12-20T14:57:15Z",
-    "updated_date": "2012-10-09T11:57:29Z",
-    "pdf_url": "https://arxiv.org/pdf/1112.4714v3",
-    "local_pdf_path": "data\\arxiv\\pdfs\\materials\\1112.4714v3.pdf",
-    "comment": "",
-    "journal_ref": "",
-    "doi": ""
-  },
-  {
-    "title": "Does a Surface Polariton Have Spin?",
-    "authors": [
-      "Konstantin Y. Bliokh",
-      "Franco Nori"
-    ],
-    "abstract": "We consider a p-polarized surface electromagnetic wave (a classical surface polariton) at the interface between the vacuum and a metal or left-handed medium. We show that the evanescent electromagnetic waves forming the surface polariton inevitably possess a backward spin energy flow, which, together with a superluminal orbital energy flow, form the total Poynting vector. This spin energy flow generates a well-defined (but not quantized) spin angular momentum of surface polaritons which is orthogonal to the propagation direction. The spin of evanescent waves arises from the imaginary longitudinal component of the electric field which makes the polarization effectively elliptical in the propagation plane. We also examine the connection between the spin and chirality of evanescent modes.",
-    "arxiv_id": "1201.2746v3",
-    "categories": [
-      "physics.optics",
-      "cond-mat.other"
-    ],
-    "primary_category": "physics.optics",
-    "published_date": "2012-01-13T05:27:31Z",
-    "updated_date": "2012-05-24T13:50:35Z",
-    "pdf_url": "https://arxiv.org/pdf/1201.2746v3",
-    "local_pdf_path": "data\\arxiv\\pdfs\\materials\\1201.2746v3.pdf",
-    "comment": "",
-    "journal_ref": "",
-    "doi": ""
-  },
-  {
-    "title": "On the robustness of acoustic black hole spectra",
-    "authors": [
-      "Stefano Finazzi",
-      "Renaud Parentani"
-    ],
-    "abstract": "We study the robustness of the spectrum emitted by an acoustic black hole by considering series of stationary flows that become either subsonic or supersonic, i.e. when the horizon disappears. We work with the superluminal Bogoliubov dispersion of Bose--Einstein condensates. We find that the spectrum remains remarkably Planckian until the horizon disappears. When the flow is everywhere supersonic, new pair creation channels open. This will be the subject of a forthcoming work.",
-    "arxiv_id": "1102.1452v1",
-    "categories": [
-      "gr-qc",
-      "cond-mat.other"
-    ],
-    "primary_category": "gr-qc",
-    "published_date": "2011-02-07T22:03:19Z",
-    "updated_date": "2011-02-07T22:03:19Z",
-    "pdf_url": "https://arxiv.org/pdf/1102.1452v1",
-    "local_pdf_path": "data\\arxiv\\pdfs\\materials\\1102.1452v1.pdf",
-    "comment": "",
-    "journal_ref": "",
-    "doi": ""
-  },
-  {
-    "title": "Storing Quantum Information via Atomic Dark Resonances",
-    "authors": [
-      "Filippo Caruso"
-    ],
-    "abstract": "In this thesis, after a brief review of some concepts of Quantum Optics, we analyze a three-level atomic system in the conditions of electromagnetically induced transparency (EIT), and we investigate the propagation of a gaussian pulse along a cigar-shaped cloud of both cold and hot atoms in EIT regime. In particular, we show that it is possible to amplify a slow propagating pulse without population inversion. We also analyze the regime of anomalous light propagation showing that it is possible to observe superluminal energy propagation. In these conditions, it is possible to imprint reversibly ('write') the information carried by the photons onto the atoms, specifically as a coherent pattern of atomic spins, and later the information stored in the atomic spins can be transferred back ('read') to the light field, implementing in this way a quantum memory. Besides, we analyze the propagation of a quantum field in an EIT medium sustaining dark state polaritons (DSP) in a quasi-particle picture. Here, the decoherence effects in this quantum memory for photons, by analyzing the fidelity of the quantum state transfer, and the emergence of parastatistics in the quasi-particle picture in gain medium are discussed. Finally, we introduce a polarization quantum memory for photons by using a tripod atomic configuration in which two ideal EIT windows appear and the two DSPs, scattering each other, show a solitonic behavior.",
-    "arxiv_id": "1001.4660v1",
-    "categories": [
-      "quant-ph",
-      "cond-mat.other",
-      "physics.atom-ph"
-    ],
-    "primary_category": "quant-ph",
-    "published_date": "2010-01-26T13:02:49Z",
-    "updated_date": "2010-01-26T13:02:49Z",
-    "pdf_url": "https://arxiv.org/pdf/1001.4660v1",
-    "local_pdf_path": "data\\arxiv\\pdfs\\materials\\1001.4660v1.pdf",
-    "comment": "",
-    "journal_ref": "",
-    "doi": ""
-  },
-  {
-    "title": "Black/White hole radiation from dispersive theories",
-    "authors": [
-      "Jean Macher",
-      "Renaud Parentani"
-    ],
-    "abstract": "We study the fluxes emitted by black holes when using dispersive field theories. We work with stationary one dimensional backgrounds which are asymptotically flat on both sides of the horizon. The asymptotic fluxes are governed by a 3x3 Bogoliubov transformation. The fluxes emitted by the corresponding white holes are regular and governed by the inverse transformation. We numerically compute the spectral properties of these fluxes for both sub- and superluminal quartic dispersion. The leading deviations with respect to the dispersionless flux are computed and shown to be governed by a critical frequency above which there is no radiation. Unlike the UV scale governing dispersion, its value critically depends on the asymptotic properties of the background. We also study the flux outside the robust regime. In particular we show that its low frequency part remains almost thermal but with a temperature which significantly differs from the standard one. Application to four dimensional black holes and Bose-Einstein condensates are in preparation.",
-    "arxiv_id": "0903.2224v3",
-    "categories": [
-      "hep-th",
-      "cond-mat.other"
-    ],
-    "primary_category": "hep-th",
-    "published_date": "2009-03-12T17:36:22Z",
-    "updated_date": "2009-06-02T08:58:09Z",
-    "pdf_url": "https://arxiv.org/pdf/0903.2224v3",
-    "local_pdf_path": "data\\arxiv\\pdfs\\materials\\0903.2224v3.pdf",
-    "comment": "",
-    "journal_ref": "",
-    "doi": ""
-  },
-  {
-    "title": "Superluminal Behaviors of Electromagnetic Near-fields",
-    "authors": [
-      "Z. Y. Wang",
-      "C. D. Xiong"
-    ],
-    "abstract": "Superluminal phenomena have been reported in many experiments of electromagnetic wave propagation, where the superluminal behaviors of evanescent waves are the most interesting ones with the important physical significances. Consider that evanescent waves are related to the near-zone fields of electromagnetic sources, based on the first principles, we study the group velocities of electromagnetic fields in near-field region, and show that they can be superluminal, which can provide a heuristic interpretation for the superluminal properties of evanescent waves.",
-    "arxiv_id": "0311061v7",
-    "categories": [
-      "physics.optics",
-      "cond-mat.mtrl-sci"
-    ],
-    "primary_category": "physics.optics",
-    "published_date": "2003-11-14T06:42:13Z",
-    "updated_date": "2006-05-16T14:15:42Z",
-    "pdf_url": "https://arxiv.org/pdf/0311061v7",
-    "local_pdf_path": null,
-    "comment": "",
-    "journal_ref": "",
-    "doi": ""
-  },
-  {
-    "title": "Time-resolved broadband analysis of slow-light propagation and   superluminal transmission of electromagnetic waves in three-dimensional   photonic crystals",
-    "authors": [
-      "J. Gomez Rivas",
-      "A. Farre Benet",
-      "J. Niehusmann",
-      "P. Haring Bolivar",
-      "H. Kurz"
-    ],
-    "abstract": "A time-resolved analysis of the amplitude and phase of THz pulses propagating through three-dimensional photonic crystals is presented. Single-cycle pulses of THz radiation allow measurements over a wide frequency range, spanning more than an octave below, at and above the bandgap of strongly dispersive photonic crystals. Transmission data provide evidence for slow group velocities at the photonic band edges and for superluminal transmission at frequencies in the gap. Our experimental results are in good agreement with finite-difference-time-domain simulations.",
-    "arxiv_id": "0412044v1",
-    "categories": [
-      "cond-mat.mtrl-sci"
-    ],
-    "primary_category": "cond-mat.mtrl-sci",
-    "published_date": "2004-12-02T12:50:32Z",
-    "updated_date": "2004-12-02T12:50:32Z",
-    "pdf_url": "https://arxiv.org/pdf/0412044v1",
-    "local_pdf_path": null,
-    "comment": "",
-    "journal_ref": "",
-    "doi": ""
-  },
-  {
-    "title": "Anti-shielding Effect and Negative Temperature in Instantaneously   Reversed Electric Fields and Left-Handed Media",
-    "authors": [
-      "Jian Qi Shen"
-    ],
-    "abstract": "The connections between the anti-shielding effect, negative absolute temperature and superluminal light propagation in both the instantaneously reversed electric field and the left-handed media are considered in the present paper. The instantaneous inversion of the exterior electric field may cause the electric dipoles into the state of negative absolute temperature and therefore give rise to a negative effective mass term of electromagnetic field (i. e., the electromagnetic field propagating inside the negative-temperature medium will acquire an imaginary rest mass), which is said to result in the potential superluminality effect of light propagation in this anti-shielding dielectric. In left-handed media, such phenomena may also arise.",
-    "arxiv_id": "0302351v1",
-    "categories": [
-      "cond-mat.stat-mech",
-      "cond-mat.mtrl-sci"
-    ],
-    "primary_category": "cond-mat.stat-mech",
-    "published_date": "2003-02-18T04:51:44Z",
-    "updated_date": "2003-02-18T04:51:44Z",
-    "pdf_url": "https://arxiv.org/pdf/0302351v1",
-    "local_pdf_path": null,
-    "comment": "",
-    "journal_ref": "",
-    "doi": ""
-  },
-  {
-    "title": "Cherenkov radiation emitted by ultrafast laser pulses and the generation   of coherent polaritons",
-    "authors": [
-      "J. K. Wahlstrand",
-      "R. Merlin"
-    ],
-    "abstract": "We report on the generation of coherent phonon polaritons in ZnTe, GaP and LiTaO$_{3}$ using ultrafast optical pulses. These polaritons are coupled modes consisting of mostly far-infrared radiation and a small phonon component, which are excited through nonlinear optical processes involving the Raman and the second-order susceptibilities (difference frequency generation). We probe their associated hybrid vibrational-electric field, in the THz range, by electro-optic sampling methods. The measured field patterns agree very well with calculations for the field due to a distribution of dipoles that follows the shape and moves with the group velocity of the optical pulses. For a tightly focused pulse, the pattern is identical to that of classical Cherenkov radiation by a moving dipole. Results for other shapes and, in particular, for the planar and transient-grating geometries, are accounted for by a convolution of the Cherenkov field due to a point dipole with the function describing the slowly-varying intensity of the pulse. Hence, polariton fields resulting from pulses of arbitrary shape can be described quantitatively in terms of expressions for the Cherenkov radiation emitted by an extended source. Using the Cherenkov approach, we recover the phase-matching conditions that lead to the selection of specific polariton wavevectors in the planar and transient grating geometry as well as the Cherenkov angle itself. The formalism can be easily extended to media exhibiting dispersion in the THz range. Calculations and experimental data for point-like and planar sources reveal significant differences between the so-called superluminal and subluminal cases where the group velocity of the optical pulses is, respectively, above and below the highest phase velocity in the infrared.",
-    "arxiv_id": "0301102v1",
-    "categories": [
-      "cond-mat.mtrl-sci"
-    ],
-    "primary_category": "cond-mat.mtrl-sci",
-    "published_date": "2003-01-08T15:49:25Z",
-    "updated_date": "2003-01-08T15:49:25Z",
-    "pdf_url": "https://arxiv.org/pdf/0301102v1",
-    "local_pdf_path": null,
-    "comment": "",
-    "journal_ref": "",
-    "doi": ""
-  }
-]

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