1,721,054 research outputs found
Aspects of hidden and manifest SL(2,R) symmetry in 2D near-horizon black-hole backgrounds
No full textVirasoro algebra with central charge c=1 on the horizon of a two-dimensional-Rindler space–time
No full text"Tunnelling" Black-Hole Radiation with phi3 Self-Interaction: One-Loop Computation for Rindler Killing Horizons
No full textTunnelling processes through black hole horizons have recently been investigated in the framework of WKB theory discovering interesting interplay with the Hawking radiation. A more precise and general account of that phenomenon has been subsequently given within the framework of QFT in curved spacetime by two of the authors of the present paper. In particular, it has been shown that, in the limit of sharp localization on opposite sides of a Killing horizon, the quantum correlation functions of a scalar field appear to have thermal nature, and the tunnelling probability is proportional to exp{−β Hawking E}. This local result is valid in every spacetime including a local Killing horizon, no field equation is necessary, while a suitable choice for the quantum state is relevant. Indeed, the two-point function has to verify a short-distance condition weaker than the Hadamard one. In this paper we consider a massive scalar quantum field with a φ 3 self-interaction and we investigate the issue whether or not the black hole radiation can be handled at perturbative level, including the renormalisation contributions. We prove that, for the simplest model of the Killing horizon generated by the boost in Minkowski spacetime, and referring to Minkowski vacuum, the tunnelling probability in the limit of sharp localization on opposite sides of the horizon preserves the thermal form proportional to exp{−β H E} even taking the one-loop renormalisation corrections into account. A similar result is expected to hold for the Unruh state in the Kruskal manifold, since that state is Hadamard and looks like Minkowski vacuum close to the horizon
Rigorous construction and Hadamard property of the Unruh state in Schwarzschild spacetime
No full textHolography, SL(2,R) symmetry, Virasoro algebra and all that in Rindler spacetime
Full text linkIt is shown that it is possible to define quantum field theory of a massless scalar free field on the event horizon of a 2D-Rindler spacetime. Free quantum field theory on the horizon enjoys diffeomorfism invariance and turns out to be unitarily and algebraically equivalent to the analogous theory of a scalar field prapogating inside Rindler spacetime, nomatter the value of the mass of the field in the bulk. More precisely, there exist a unique transformation that realizes the bulk-boundary correspondence upon an appropriate choice for Fock representation spaces. Secondly, the found correspondence is a subcase of an analogous algebraic correspondence described by the injective homomorphisms of the abstract algebras of observables generated by abstract quantum free-field operators. These field operators are smeared with suitable test functions in the bulk and exact 1-forms on the horizon. In this sense the correspondence is independent from the chosen vacua. It is proven that, under that correspondence the 'hidden' SL(2,R) quantum symmetry found in a previous work gets a clear geometric meaning, it being associated with a group of diffeomorphisms of the horizon itself. Finally it is found that there is a possible enlargement of the quantum symmetry on the horizon to a quantum Virasoro symmetry associated with vector fields on the event horizon
Bose-Einstein condensate and Spontaneous Breaking of Conformal Symmetry on Killing Horizons
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Bell-inequality violation by entangled single-photon states generated from a laser, an LED, or a halogen lamp
Full text linkIn single-particle or intraparticle entanglement, two degrees of freedom of a single particle, e.g., momentum and polarization of a single photon, are entangled. Single-particle entanglement is a resource that can be exploited both in quantum communication protocols and in experimental tests of noncontextuality based on the Kochen-Specker theorem. Here we show that single-particle entangled states of single photons can be produced from attenuated classical sources of light. To experimentally certify the single-particle entanglement, we perform a Bell test, observing a violation of the Clauser, Horne, Shimony, and Holt inequality. We show that single-particle entanglement can be achieved even in a classical light beam, provided that first-order coherence is maintained between the degrees of freedom involved in the entanglement. This demonstrates that cheap, compact, and lowpower photon sources can be used to generate single-particle entangled photons which could be a resource for quantum technology applications
Rigorous steps towards holography in asymptotically flat spacetimes
No full textScalar QFT on the boundary J+ at null infinity of a general asymptotically flat 4D spacetime is constructed using the algebraic approach based on Weyl algebra associated to a BMSinvariant symplectic form. The constructed theory turns out to be invariant under a suitable strongly continuous unitary representation of the BMS group with manifest meaning when the fields are interpreted as suitable extensions to J+ of massless minimally coupled fields propagating in the bulk. The group theoretical analysis of the found unitary BMS representation proves that such a field on J+ coincides with the natural wave function constructed out of the unitary BMS irreducible representation induced from the little group, the semidirect product between SO(2) and the two-dimensional translations group. This wave function is massless with respect to the notion of mass for BMS representation theory. The presented result proposes a natural criterion to solve the long standing problem of the topology of BMS group. Indeed the found natural correspondence of quantum field theories holds only if the BMS group is equipped with the nuclear topology rejecting instead the Hilbert one. Eventually some theorems towards a holographic description on J+ of QFT in the bulk are established at level of C* algebras of fields for strongly asymptotically predictable spacetimes. It is proved that preservation of a certain symplectic form implies the existence of an injective *-homomorphism from the Weyl algebra of fields of the bulk into that associated with the boundary J+. Those results are, in particular, applied to 4D Minkowski spacetime where a nice interplay between Poincaré invariance in the bulk and BMS invariance on the boundary at null infinity is established at level of QFT. It arises that, in this case, the *- homomorphism admits unitary implementation and Minkowski vacuum is mapped into the BMS invariant vacuum on J+
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